Tow/Haul button......and Auto 4wd

2kwik4u · Post by **2kwik4u** » Thu May 11, 2006 12:35 pm

Just curious if anyone else has a Tow/Haul button. I don't, but want one.

Also anyone have the Auto 4wd option? Was it an option?

I've been researching the Tow/Haul and how that works. Aparantly it is a simple grounding of a PCM pin, and alerts the PCM to look into a seperate table for shift points, and line pressures for the transmission. I'll be purchasing EFILive here in a few weeks, and have every intention of setting up a Tow/Haul button on my truck shortly there after.

I've also got the thought of doing the same modifications to my roomates Xtreme with a 4L60E in it, and making the secondary table a performance shift setting with raised WOT shift points, and significantly firmer shifts, and things of that nature.

Thoughts? Ideas?

F9K9 · Post by **F9K9** » Thu May 11, 2006 1:43 pm

2kwik4u wrote:Just curious if anyone else has a Tow/Haul button. I don't, but want one. Also anyone have the Auto 4wd option? Was it an option?

I have not heard of anyone mentioning either one as an option for the CCs

killian96ss · Post by **killian96ss** » Thu May 11, 2006 2:39 pm

Most of the Silverado's have the tow/haul button on the column shifter. If you could somehow adapt this to the S10 it would be a cool mod, but I'm not sure you will be able to do it with our stock PCM.

None of the S10 Crew Cabs came with auto 4wd, but the S10 Blazers did, so it is possible to convert over to full time 4wd, but you will need a different t-case, front diff, switches, and wiring to make it work.

Steve

JimmyDiamond · Post by **JimmyDiamond** » Thu May 11, 2006 3:15 pm

I've got one

killian96ss · Post by **killian96ss** » Thu May 11, 2006 3:27 pm

JimmyDiamond wrote:I've got one

Which one do you have, the tow/haul mode or the auto 4wd?

Steve

JimmyDiamond · Post by **JimmyDiamond** » Thu May 11, 2006 6:00 pm

killian96ss wrote:
JimmyDiamond wrote:I've got one
Which one do you have, the tow/haul mode or the auto 4wd?

Steve

Both!!

Post by **Walt** » Thu May 11, 2006 6:01 pm

The tow/haul mode basically makes the tranny hold a gear longer correct?

JimmyDiamond · Post by **JimmyDiamond** » Thu May 11, 2006 6:12 pm

wamason wrote:The tow/haul mode basically makes the tranny hold a gear longer correct?

Yes and it also downshifts faster. I engage it often when driving because IMO it makes the driveability better.

Post by **Walt** » Thu May 11, 2006 9:16 pm

I would love to have it here since I live in the hills

2kwik4u · Post by **2kwik4u** » Fri May 12, 2006 3:07 am

From what I've been reading it's a pretty simple "ground a PCM pin" to make it work.

I need to get ahold of some shop manuals, and study the schematice of it all, but I really don't think it's that terribly dfficult.

I knew up front the Auto 4wd would be alot of hardparts, and I'm not that enthused.....If I was I'd be swapping to a 4L80E, Sy/Ty transfer case, and making the thing AWD . I was really just more curious if it was offered as an option or not.

JimmyDiamond · Post by **JimmyDiamond** » Fri May 12, 2006 4:44 am

I think the Auto 4wd or "autotrac" was only ever available on the SUV version of the S-series. I don't think it was ever available on the trucks. It really is a nice feature though when you're driving 9 hours for Christmas and the interestate is snowy and icy with some clear spots. You can put it in auto 4wd and not kill your mileage like 4hi would.

2kwik4u · Post by **2kwik4u** » Fri May 12, 2006 7:09 am

JimmyDiamond wrote:I think the Auto 4wd or "autotrac" was only ever available on the SUV version of the S-series. I don't think it was ever available on the trucks. It really is a nice feature though when you're driving 9 hours for Christmas and the interestate is snowy and icy with some clear spots. You can put it in auto 4wd and not kill your mileage like 4hi would.

My dads '99 envoy has it, and he likes it (although that thing is so heavy I dunno HTF he drives it anywhere, I didn't like driving it at all, however I kinda enjoy my ZR5...Although neither is as fun as the Xtreme

).

Anyway, back to the topic at hand. I've been reading a bunch on LS1tech.com this morning, and have found a few good threads on how all that works, but I'm not 100% sure I can get it working just yet. I really need to get my hands on a copy of EFILive before I can make a 100% verdict.

JimmyDiamond · Post by **JimmyDiamond** » Fri May 12, 2006 7:12 am

Talk to "Blades" or whatever his name is now back over on SSF. I think he has or had a ZR2 Blazer and went through all the fun wiring up a tow haul button in the console.

rlith · Post by **rlith** » Wed May 17, 2006 12:53 pm

JimmyDiamond wrote:Talk to "Blades" or whatever his name is now back over on SSF. I think he has or had a ZR2 Blazer and went through all the fun wiring up a tow haul button in the console.

Yeah, he tried, but after all the mucking around, the PCM just wouldn't accept it even though he used a factory harness. Since I have a B&M electronic shift improver (which really does the same thing) I made mine turn my amp off and on...

crew cab sonoma · Post by **crew cab sonoma** » Fri May 26, 2006 8:07 am

the B&M electronic shift improver only bumps line pressure to increase shift firmness. it does not alter shift points, like the OEM tow/haul feature does.

2kwik4u · Post by **2kwik4u** » Thu Jun 08, 2006 9:36 am

Little update for you guys...

Been researching the stock tune on these trucks and bumped across this setting.

http://s91879901.onlinehome.us/gallery/ ... aul_select

It's the default tune setting from an '01 4.3 with a 4L60E. The "performance" mode on trucks is used with the Tow/Haul button on some models. I'll need to change this setting to "one switch", and then temp-ground the PCM pin to make it work.

I'll grab some screenshots of the upshift, and downshift tables if anyone wants them to see the difference.

killian96ss · Post by **killian96ss** » Thu Jun 08, 2006 11:09 am

2kwik4u wrote:I'll grab some screenshots of the upshift, and downshift tables if anyone wants them to see the difference.

I would like to see the shift tables!

Steve

2kwik4u · Post by **2kwik4u** » Thu Jun 08, 2006 11:18 am

killian96ss wrote:
2kwik4u wrote:I'll grab some screenshots of the upshift, and downshift tables if anyone wants them to see the difference.
I would like to see the shift tables!

Steve

Gimme a few minutes....I'll try to make them as readable/understandable as possible....Look for another post though, don't want to muddy the waters in this one.

04crewvt · Post by **04crewvt** » Thu Jun 08, 2006 4:20 pm

But you should let Walt have something to do

daevans315 · Post by **daevans315** » Sat Jun 10, 2006 6:58 am

I'm very interested in this thread. A tow haul button is something I've always wondered about putting on the Crew.

I've noticed with a trailer, and accelerating up hill under 'light' throttle my crew stumbles on 1st to 2nd shift. Kind of like it hits 2nd and realizes there is a load it considers going back into first. I'm sure the mandatory higher shift points would take care of that if nothing else. I've also noticed on my dad's Tahoe that when it’s in tow haul mode, almost as soon as you lift your foot off the gas, you get engine braking, even in OD on the interstate. I can see that saving some brakes.

Keep up the good work.

2kwik4u · Post by **2kwik4u** » Sat Jun 10, 2006 10:31 am

daevans315 wrote:I'm very interested in this thread. A tow haul button is something I've always wondered about putting on the Crew.

I've noticed with a trailer, and accelerating up hill under 'light' throttle mine crew stumbles on 1st to 2nd shift. Kind of like when it hits 2nd and realizes there is a load it considers going back into first. I'm sure the mandatory higher shift points would take care of that if nothing else. I've also noticed on my dad's Tahoe that when it’s in tow haul mode, almost as soon as you lift your foot off the gas, you get engine braking, even in OD on the interstate. I can see that saving some brakes.

Keep up the good work.

The shift tables, and the TCC lockup tables (see other thread) are exactly what cause your dads tahoe to feel that way.

I would assume that your 1-2 shift issue is most likely Torque Management pulling a BUNCH of timing during the shift. I logged the other day something like 29 degrees of timing being pulled during the shift, which cause an obvious decrese in torque.

I'll let you all know how it progresses. Been researching through all the diagrams I can find to figure out where the Tow/Haul input is located on either the BCM or PCM.

crew cab sonoma · Post by **crew cab sonoma** » Mon Jun 19, 2006 4:42 am

2kwik4u wrote: I would assume that your 1-2 shift issue is most likely Torque Management pulling a BUNCH of timing during the shift. I logged the other day something like 29 degrees of timing being pulled during the shift, which cause an obvious decrese in torque.

agreed. ive also noticed Torque Management pulling such huge ammounts of timing on upshifts, on my own truck with a scan tool.

Fixed quote -W

daevans315 · Post by **daevans315** » Mon Jun 19, 2006 5:51 am

Looks like these guys are on the same track. Have they gotten further us?

http://www.ls1tech.com/forums/showthrea ... t=tow+haul

2kwik4u · Post by **2kwik4u** » Mon Jun 19, 2006 6:58 am

Looks like they are at the same point we are.

daevans315 · Post by **daevans315** » Mon Jun 19, 2006 7:10 am

What are the crew's set to by default in this table. They aren't to specific where this setting is... but were you able to find it with EFLive?

These options enable the various shift pattern modes within the PCM.
Note: J1 is the 'BLUE' connector on the PCM.
Switch types used must be momentary connect to ground.

No Switch = Performance mode via a switch is not functional.
One Switch = Performance mode via a switch can be activated (J1 - pin71).
Two Switches = Performance mode via a switch can be activated (J1 - pin71), and Manual Mode can be activated (J1 - pin31).
'C2 Data Bus' = Shift pattern modes are sent on the data bus to the PCM from another module, eg - BCM.

BTW.. I was google'ing this issue and found your forum posts on EFILive's site from 2005.. I was all excited to find someone else with an S-10 out there looking and the same issues... then I realized it was you.

2kwik4u · Post by **2kwik4u** » Mon Jun 19, 2006 7:15 am

daevans315 wrote:What are the crew's set to by default in this table They aren't to specific where this setting is... but were you able to find it with EFLive?

These options enable the various shift pattern modes within the PCM.
Note: J1 is the 'BLUE' connector on the PCM.
Switch types used must be momentary connect to ground.

No Switch = Performance mode via a switch is not functional.
One Switch = Performance mode via a switch can be activated (J1 - pin71).
Two Switches = Performance mode via a switch can be activated (J1 - pin71), and Manual Mode can be activated (J1 - pin31).
'C2 Data Bus' = Shift pattern modes are sent on the data bus to the PCM from another module, eg - BCM.

Yea I found it, and it's set stock to

Code: Select all

'C2 Data Bus' = Shift pattern modes are sent on the data bus to the PCM from another module, eg - BCM.

Which tells me it's looking for a signal from the BCM. Kinda makes sense. Perhaps the wiring is already there, and we simply have to find it?!?! :dunno:

I broke the motor in the Xtreme this weekend, so this project is taking a bit of a back burner for awhile

daevans315 · Post by **daevans315** » Mon Jun 19, 2006 10:41 am

I found a wiring diagram for 2002 full size 4.3 4l60e. It shows the tow haul button to the PCM connection.

http://www.ubergobbie.com/2002chevy4l60e43.jpg

2kwik4u · Post by **2kwik4u** » Mon Jun 19, 2006 11:43 am

Momentary ground to the light blue wire.....SWEET

thanks for the info on that.....

Post by **Walt** » Mon Jun 19, 2006 12:34 pm

2kwik4u wrote:Momentary ground to the light blue wire.....SWEET

thanks for the info on that.....

Soooo.....does this mean that we can get tow/haul mode on our CC's now?

daevans315 · Post by **daevans315** » Mon Jun 19, 2006 12:35 pm

Here is the BCM connector lay out for the full size 4.3. The LT Blue one is the last one on the connector so it should be easy to find.

http://www.ubergobbie.com/bcmconnectorc1.jpg

Now the question is, how standard are the BCM's? Will we have a blue wire? If not, who will be the first to touch that pin to ground..... At least with this info we have a bunch of wires to check and see if they match between the full size and the s-10.
How much is a new BCM if you fry it?

I'll check when I get home, but it will be a couple hours.

2kwik4u · Post by **2kwik4u** » Mon Jun 19, 2006 1:18 pm

Walt wrote:
2kwik4u wrote:Momentary ground to the light blue wire.....SWEET

thanks for the info on that.....
Soooo.....does this mean that we can get tow/haul mode on our CC's now?

Maybe.....

The BCM's have a calibration just like the PCM. I put fog lights on my Xtreme with all factory wiring (used to just be an LS), and they didn't work since the BCM had no idea to look for them.

The chances of getting a dealership to flash the PCM is slim to none as well from everywhere I've checked.

SO...it's a trial and error thing. I'm totally expecting it to NOT work through the BCM (based on previous experience), and having to change the above mentioned setting in the PCM, and temp-grounding a wire there.

daevans315 · Post by **daevans315** » Mon Jun 19, 2006 2:53 pm

2kwik4u wrote: SO...it's a trial and error thing. I'm totally expecting it to NOT work through the BCM (based on previous experience), and having to change the above mentioned setting in the PCM, and temp-grounding a wire there.

Well the first test......

The wires on the BMC plug all matched the full size so I used a clamp on wire splice(something I generally despise) and spliced on a 6" run of wire to the LT blue wire a few inches from the plug. With the motor running, I touched it to ground... No magic white smoke came out of the BCM so I took it for for a drive.... I could tell no change what so ever.

I did a couple key offs and back on, sometimes touching to ground after starting and sometimes not. I could see no change in shift points. On my Dads Tahoe its VERY noticeable change, especially under light loads and light throttle. So I'm guessing that’s a no go. Mine is a 2002 maybe other years have the right "flash" in the BCM?

If not I guess its on to PCM programming.

daevans315 · Post by **daevans315** » Mon Jun 19, 2006 3:15 pm

2kwik4u · Post by **2kwik4u** » Mon Jun 19, 2006 4:30 pm

Yep, thats the right test to be making......SOrry it didn't work for you, but thanks for the report back. It's a start.

daevans315 · Post by **daevans315** » Tue Jun 20, 2006 8:51 am

I'm trying to work this from a different angle, as I don't have easy access to EFILive. (A friend of a friend has a copy but I hate to spend the $100 for a license for somebody else’s software)
Also, adding the Pin to the PCM looks like it might be a real pain.

I was thinking...

What if I were to swap a BCM out of a Blazer or Jimmy that had the tow haul button. If I found one with power windows and fog lights, there shouldn’t be much difference right? The rear window defogger and wiper maybe? From we have seen in this tread, an accessory that we had that the Blazer didn't would be more of an issue. What would that be? Would the blazer likely have the 4L80E? Would that make a difference?

GMPartsDirect.com lists the BCM of 2002 blazers as a $140 part. They list several so I’m guessing that they are the different programs for the different trim levels.?
Maybe a junkyard swap is in order?

2kwik4u · Post by **2kwik4u** » Tue Jun 20, 2006 9:22 am

Decent idea, but not real practical, heres why.

If the PCM, and the BCM don't talk to each other your truck will go nowhere. The vehicle Anti-Theft system gets data from the BCM, and confirms that data with the data in the PCM. If they don't match, truck doesn't start. Again if you have EFILive, you can disable the VATS, and get around this, however you're back to needing the $100, and a copy of EFILive.

In all honesty I think there is a TON of value to a good tune. Removal of Torque Management (or at least a reduction), as well as some spark, and fuel tuning will net good results. Along with some of these other features we are trying to get.

I also believe that the BCM from GMPD.com doesn't come flashed, so you would have to have it flashed by a dealer. Who will only do it in the truck, and will only use your VIN number (thus making it a spare Crew Cab BCM). I went through this mess with the Xtreme, NONE of the dealers around here would work with me on what I wanted.

daevans315 · Post by **daevans315** » Wed Jun 21, 2006 5:37 am

What 'version' of EFI live do you have? I may just bite the bullet and buy a copy.
My other option is to go with PCM4less.com and have them set it up for me.

2kwik4u · Post by **2kwik4u** » Wed Jun 21, 2006 6:23 am

daevans315 wrote:What 'version' of EFI live do you have? I may just bite the bullet and buy a copy.
My other option is to go with PCM4less.com and have them set it up for me.

Haven't purchased it yet, however I will be getting Flashscan V7.x.x (whatever the most current is)

I would simply have PCM4Less do it for you, if you don't intend to tune the truck beyond a simple tune.

I have other uses for the software, so the $800 price tag is a bit easier to swallow.

killian96ss · Post by **killian96ss** » Wed Jun 21, 2006 7:13 am

daevans315 wrote:My other option is to go with PCM4less.com and have them set it up for me.

I have their tuning in my SS and it is so much better than the Hypercrap tuning. I picked up a solid 30 hp over the Hypercrap with the new PCM4less tune. As soon as the extended warranty runs out on my CC I will be selling my Hypercrap and getting a PCM4less tune. The current price for programming the PCM's in our trucks is $250 and it is well worth it.

Steve

daevans315 · Post by **daevans315** » Thu Jun 22, 2006 6:40 am

I've started an email conversation with PCMforless.com. They are looking into what exactly is possible with the PCM. I've given him the info from this forum and the ls1tech.com site. Now its just a wait and see. I'll keep you posted.

2kwik4u · Post by **2kwik4u** » Thu Jun 22, 2006 7:04 am

D0409 <---Location in the PCM for the Shift Pattern Select option.

Jigg · Post by **Jigg** » Thu Jun 22, 2006 8:12 am

This might be a stupid question, but i'm going to ask it anyways... why not just get a B&M electronic shift+? Completely switchable, easy to install, increases line pressure and changes shift points, cheap, easy to install. No?

2kwik4u · Post by **2kwik4u** » Thu Jun 22, 2006 9:09 am

Jigg wrote:This might be a stupid question, but i'm going to ask it anyways... why not just get a B&M electronic shift+? Completely switchable, easy to install, increases line pressure and changes shift points, cheap, easy to install. No?

Not a stupid question at all.

While a semi-attractive solution. Lying to the PCM causes nothing but problems in my experience. I've had a Greddy Emanage (Piggy back fuel, and timing computer)installed on the Xtreme, as well as a myriad of other gadgets like that, and they NEVER provided the level of performance of a PCM tune. Garbage in leads to garbage out. Feed the PCM bad info, and it will make bad decisions. I'll personally use a piggy-back as a last resort from this point forward.

There is more to be had from a good tune, than JUST the tow haul button. TM removal, fuel and spark changes, as well as electric fan control, and other nice features like that.

Does the Shift+ change convertor lockup? What about kickdown points associated with TP, and MPH? Does it take into account for the PCM's adaptive shift tables? IMO, it's a gimmick for more than just the above listed reasons.

killian96ss · Post by **killian96ss** » Thu Jun 22, 2006 9:39 am

Jigg wrote:This might be a stupid question, but i'm going to ask it anyways... why not just get a B&M electronic shift+? Completely switchable, easy to install, increases line pressure and changes shift points, cheap, easy to install. No?

The B&M shift improver only increases line pressure, it doesn't change the shift points. It basically has 3 settings, #1 = stock shifts, #2 = firmer shifts, and #3 = extremely firm shifts for racing. The # 3 position is very harsh and if you use it too much you will eventually damage the transmission. IMHO the B&M shift improver is garbage. If you want good reliable shifts with the 4L60E install a Transgo shift kit. It is currently the best shift kit available for our transmissions.

Steve

Jigg · Post by **Jigg** » Thu Jun 22, 2006 10:03 am

Interesting.

I searched around on ZR2.com to find a post i remember by Mike Copeland:

"Torque management is done to help transmission life, as well as other driveline parts. It is not inside the trans, it is a function of the PCM software. It can be turned off, bit the PCM will need to be recalibrated by someone that can open the software. A HPP3 can not turn it off.

The HPP3 will increase line pressure, and that makes the shift faster and more agressive. This will help trans life, because there is less slippage in the band and clutches.

Changing the servo to a aftermarket unit (or a Corvette part) will make the 1-2 shift more firm. This will help the 1-2 band last a little longer, and firm the 1-2 shift. It will not change anything else in the transmission."

I took this post (the part about line pressure), to mean that more line pressure = more tranny life. For the past month or so, since i've had my 33's, i've had my B&M set on the 3rd setting. The only time it's rough is coming into 1st from Park, and that's only sometimes. The rest of the time, it's firm, but only just as firm as it was on the 2nd setting when i had 31's. (if that makes sense)

There was also another one about tow/haul mode (not sure if it'll help, as most of this is, admittedly, over my head):

"OK, here is how the "tow / haul" mode works. When you push the button on the dash, a input is sent to the BCM (body computer). It then sends a message (Class II) to the PCM, and the cluster. The PCM changes the shift points and TCC lock up point. The cluster turns the "tow / haul" light on. If, a very big if, the PCM software ws set up to recieve this message, it could work. The BCM would also have to transmit the message, and I don't know if a truck BCM can do this.

The easest way to change the shift points would be a aftermarket controller, like the B&M select-a-shift."

From here:

http://66.221.218.45/cgi-bin/ultimatebb ... 794#000000

daevans315 · Post by **daevans315** » Thu Jun 22, 2006 12:17 pm

I tried 2 dealerships yesterday to ask about a BCM flash. I got the flat no's that others were receiving. I tried a 3rd today and I got so far as an agreement from the service manager to do it and an appointment setup. Then 15 mins later I got a call back. The service manager had apparently called up the chain to verify it was ok and got shot down. I pushed a little saying I would be happy to sign a "I'm not going to sue you" letter but no go.

So back to the email exchange with PCM4less.com. I think that is what I'm going to go with.

2kwik4u · Post by **2kwik4u** » Thu Jun 22, 2006 12:21 pm

daevans315 wrote:So back to the email exchange with PCM4less.com. I think that is what I'm going to go with.

It is hands down the best bang/buck mod you can do to the trans/motor IMO.

I think they even offer re-tunes for like $50 or so if you change your combo later.

I promise you won't be dissappointed.

Jigg · Post by **Jigg** » Thu Jun 22, 2006 12:46 pm

I've been searching for quite awhile trying to find a Dyno sheet (or even just posted results) of the PCMforless tuning on a 4.3L. Any idea what the actual HP gain is?

killian96ss · Post by **killian96ss** » Thu Jun 22, 2006 12:53 pm

Jigg wrote:Torque management is done to help transmission life, as well as other driveline parts. It is not inside the trans, it is a function of the PCM software. It can be turned off, bit the PCM will need to be recalibrated by someone that can open the software.

This is true, but our 4.3's are nowhere near powerful enough to cause damage to the tranny or driveline parts, so torque management in our trucks is useless.

The easest way to change the shift points would be a aftermarket controller, like the B&M select-a-shift."

What is the B&M select a shift?

I don't see anything like this on their web site.

Steve

Jigg · Post by **Jigg** » Thu Jun 22, 2006 2:23 pm

I'm pretty sure he's referring to the shift+

daevans315 · Post by **daevans315** » Fri Jun 23, 2006 5:34 am

Well I jumped. Ordered a PCM for less PCM today. He is going to do a basic tune on it and change the PCM to look at Pin 71 for the tow haul.

Now.... Where are the Blazers tow haul button and indicator?
Console shift for the button and dash indicator? Correct?
Dads full size has a button on the end of the column shifter and the indicator is inset into the shifter handle. This looks really cool but I think his shifter has vastly different bends to it than the one on the crew.

I don't have the desire to do a console change over right now, so any suggestions on where to put the button?
I'm sure for starters its going to be a $2 radio shack momentary contact button dangling by the wires under the dash but l want to do something considerably better than that once I know it works.
An indicator would be cool but I don't think it’s really necessary.

2kwik4u · Post by **2kwik4u** » Fri Jun 23, 2006 5:45 am

daevans315 wrote:Well I jumped. Ordered a PCM for less PCM today. He is going to do a basic tune on it and change the PCM to look at Pin 71 for the tow haul.

Now.... Where are the Blazers tow haul button and indicator?
Console shift for the button and dash indicator? Correct?
Dads full size has a button on the end of the column shifter and the indicator is inset into the shifter handle. This looks really cool but I think his shifter has vastly different bends to it than the one on the crew.

I don't have the desire to do a console change over right now, so any suggestions on where to put the button?
I'm sure for starters its going to be a $2 radio shack momentary contact button dangling by the wires under the dash but l want to do something considerably better than that once I know it works.
An indicator would be cool but I don't think it’s really necessary.

Glad to hear your moving forward on that.

I personally would put the button in the ash tray with a simple radioshack momentary switch.

The dash light SHOULD iluminate on its own, although I'm not 100% sure. I know the guys that convert to a floor shifter still have hte PRND321 indicator work, so thats what I'm basing my reply on.

Let me know how that PCM4Less tune works out for you. Did he give you any "specs" on what he's changing? Like removing TM, tuning the fuel and spark, changing the Pin 71 look.....anything else?

daevans315 · Post by **daevans315** » Fri Jun 23, 2006 6:01 am

For the indicator.. Do we even have a bulb in that location? I don't know. Also, since we have removed the BCM from the picture will a signal get sent back to the BCM to light the dash light? I will be interesting. I hope that the indicator will work but I would put $$$ on it not working.

Bryan(at PCMforless) and I were very specific on what we were doing with the tow haul button but not very specific on everything else. I did ask him to disable the VIN security. Hoping that if the PIN 71 doesn't work I could then attempt a swap of a BCM from a blazer. Here is a snip from our email.

I do have an 02 PCM core here. I have PCM pins here as well that I can send with the PCM that you can insert into the harness and then wire up to a momentary switch. I can also pick you up power, clean up the shifts, improve the shift point and also get you some mileage as well.

After the posts here and on several other boards I pretty much decided to trust him on the general tuning. I could not find anyone disappointed in his work.

2kwik4u · Post by **2kwik4u** » Fri Jun 23, 2006 7:06 am

His general tuning is good...just didn't know if he mentioned anything about his specific changes.

No biggie, I'm not I'd want to go saying what my tunes consisted of if I was in his position either.

Very cool of him to send some PCM pins for you to use as well.

daevans315 · Post by **daevans315** » Mon Jun 26, 2006 5:40 pm

Oops.. I got delayed a day on the new PCM. I filled out the order form for "all V6 GM Vehicles" instead of what I should have chosen which was "trucks 1996 and newer." I can see that argument going either way, but its straightened out now.

daevans315 · Post by **daevans315** » Tue Jun 27, 2006 11:11 am

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I'll let you guys know over the weekend how it all works out.

daevans315 · Post by **daevans315** » Fri Jun 30, 2006 2:45 pm

Well Here is how it worked out.... All is not lost.. but the first try was not good. Here is the letter back to PCMforless.

I received my new PCM today and installed it. I immediately get a P1336 code (Crankshaft Position Variation ). A quick goggle shows that this may happen after a PCM replacement and several sites give a reset procedure. Unfortunately I don't have the needed scan tool to perform it. Reseting the code in the PCM only removes the code for a few seconds. The SES light comes back on immediately with the same code.
I switched back to my original computer and the code went away. Back to yours and it came back. I disconnected the battery during each switch.

Also, I have not been able to tell any difference in the shift points after shorting pin J1 -71 to ground. I wanted to verify that that setting had been made in the computer and the "performance" shift tables did indeed have tow shift tables in them. I was hoping the the above code may put the PCM in a limp home mode and all other signals may be ignored.

2kwik4u · Post by **2kwik4u** » Sat Jul 01, 2006 5:31 am

Interesting development. Hate to hear you are having a crank re-learn problem. I've heard of a few of those, but they seem rare....Do you know anyone with EFILive? I think the bi-directional controls can do that relearn for you without burning a license.

Keep us posted on the progress.

How does the tune feel otherwise? Good/Bad/Indifferent?

daevans315 · Post by **daevans315** » Sat Jul 01, 2006 2:42 pm

2kwik4u wrote:
How does the tune feel otherwise? Good/Bad/Indifferent?

I can tell no differance in the tune by the seat of the pants. No firmer shifts or any differance in acceleration. I'm really hoping that the PCM is in limp home mode becauses of the code. I've also only driven it about 10 miles... it could still be in learn mode. I know it took it a few mins to get the idle speed correct.

daevans315 · Post by **daevans315** » Sun Jul 02, 2006 5:38 pm

I just got an email back for PCMFORLESS, excellent customer service for a holiday weekend. I really wasn't expecting to hear back until Wed.

The code will not limp the truck. Yes, I did do the performance tables, so there must be more we need to do. If you don't have a way to clear the 1336 (this happens occasionally with exchange PCM's) you can send me over your original and I will load the program into it and send it right over and then you won't have to do the 1336 relearn since that PCM will already be learned to your truck.
Thanks,
Bryan

I am sending him back my original PCM for him to redo the flash on. I drove the truck about 80 miles today with his PCM in it. Half of that was towing a 12x7 Flat bed trailer at about 2,000 pounds. I really can't say that I can tell much difference. I ran some pretty good hills coming up out of the river valley and I was surprised it didn't drop from OD to 3rd with the trailer. Over all I can say the change is minimal if anything. I still have some hope that the SES light being on is still holding back my performance some.

So, I have double and triple checked my wiring and I’m going to check it again but I'm am 99.9% sure I'm getting a good ground to pin 71. I'm ready to hear some more ideas on how to get this silly thing working. This is starting to become a mission now... I really don't need this 'feature' but Chevy refusing to flash the BCM has really annoyed me.

I have a couple days to figure out if I want other setting changed in the PCM before he gets my original and flashes it.

daevans315 · Post by **daevans315** » Sun Jul 02, 2006 5:47 pm

One thing that just popped into my head..... One thing I haven't verified is that I should be grounding Pin 71. I just assumed that since the BCM pin needed a temporary ground to activate, the same would be true for the PCM. The doc's I can find simply say "can be activated via Pin 71" up until now I assumed that that meant a temporary ground, but maybe its looking for a different signal? Maybe???

EDIT*** never mind. The LS1Tech thread states a momentary contact to ground for Pin 71.

2kwik4u · Post by **2kwik4u** » Sun Jul 02, 2006 5:55 pm

It's supposed to be a TEMPORARY ground. Not a constant ground. If you have a constant ground then you are wiring it in such a manner that it thinks you are holding the switch in. I would start the truck. Touch the wire to ground, then disconnect it. It only needs to be grounded for a second or so to activate it.

Thats what I gather from the schematics I've seen anyway.

Also on the performance issue. The PCM uses TWO spark tables, a low and a high. The typical process is to copy the high table to the low when tuning, then replace the low back to original once tuned. The idea here is that when you are tuning, some of the SES flags will dump the PCM into the low octane table, and you want to remain in the high table at all times when tuning. I'm not sure how PCM4Less does his tunes, however it is possible (and probably I would think) that he put the low spark table back to stock, as that leaves a good deal of safety in the tune. If this is the case, I'm sure there is some power being left on the table with the code being set, as you are running in the low spark table.

I'm not sure how that might effect the fueling in the PCM, however I am going to think that there is some safety net there as well. I'll try and study the tables tomorrow night,and see what I can figure out.

In other thoughts. Have you taken an unloaded WOT run yet? If so can you comment on how the 1-2 shift feels under WOT? I would expect it to not fall on it's face as it previously did (and how mine does). That should be a simple test to see if TM has been removed or not. The shift should be nice and clean. Not harsh, but simply shift quickly and precisely.

Also....Much thanks for being the guinnea pig on this one. I don't have the cashola right now to be doing the testing myself, and I know the entire community thanks you for the reports, and updates.

daevans315 · Post by **daevans315** » Mon Jul 03, 2006 7:02 am

I've been doing just a momentary ground. Anywhere for <.5 second to 2 or 3 seconds. I've been doing it all under the hood. I started with the wire out of the PIN to one side of a momentary contact push button. The other side of the switch to a screw on the firewall. That tested with a ohm meter as a good ground (back to the negative battery terminal). I suspected maybe a bad switch. I now just have a length of wire with no switch that I touch to the negative battery terminal or the outside of the alternator....ect some VERY good ground source. I've been very careful to touch and remove.. not to get a off again - on again ground that might switch back and forth several times to tow haul. I cap the end of the wire when I'm done so it doesn't accidentally hit ground before I get back in the cab to drive it. I'm doing all this with the engine running.

I will have some more time to play with it over the 4th.

I hope your right on the performance tune and the SES light. Now that I think about it .. I did several partial throttle shifts while under a load. The first to 2nd gear stumble was gone and I didn’t really even think about it. So that is an improvement.

WOT shifts could be a little firmer. They are not as firm as the shifts the hypertech gives you with a 4l60e and shift firmness turned on, but they could be a little firmer.

2kwik4u · Post by **2kwik4u** » Mon Jul 03, 2006 7:19 am

Firm is a subjective word....however IMO you shouldn't "feel" a bang or hit of any sort when it shifts. It should be precise, and quick. A "bang" shift is a bit to "firm" IMO, but it's all in what you like.

Ultimately if it doesn't pull timing on the shift then that will net you some large gains in performance as well.

Keep us posted.

daevans315 · Post by **daevans315** » Sun Jul 09, 2006 4:58 pm

Well I had some time to look at the wiring. I even redid the crimp connection with a solder and shrink tubing. I removed the plug to the PCM and verified that the Pin was indeed in the J1, blue and pin 71. I am defiantly getting a good ground there and no change. My original PCM is in the hands of UPS and on its way back to me. It will be here Tuesday. Should be exactly the same setup as the last one.... maybe it will work better.

On the plus side, I have about 300 miles on this computer. I think I've picked up a few HP in the last few days. Also, I've gotten all the mid range gas out of the tank after 2 fill ups of premium. I'm thinking the 'loaner' PCM finally got out of 'learn' mode. The shifts are the same as reported before but I defiantly have picked up some HP.

Finally, I towed a friends project trailer about 75 miles yesterday. It’s a 12 x 8.5 flat bed tandem axle. He just got done having 800 pounds of steel welded onto it to make a custom high\low travel trailer. (This is a side project that gets into another one of my hobbies click this link if your interested. http://www.enslin.com/rae/gypsy/vardo03.html )
The crew handled it well at about 2,500 pounds and a good deal of wind load. Cruise control would unlock torque converter every time there was even a little hill so I just towed in 3rd some. WOW that eats the gas. I switched to running the throttle myself and could keep in locked up pretty well.
I haven’t looked through the 'tow' shift tables. (or completely understand what I’m looking at when I do.

) Does it take more throttle to unlock the torque converter? I would hope so it seemed to have the HP, just the cruise control would get impatient when it would get a mph or 2 behind.

PS.. The Crew is teasing me. I was getting into it today and the sun was just right on the dash so I could see the cut outs for all the dash indicator lights… there was the tow haul light right there staring at me at the top center of the dash.

2kwik4u · Post by **2kwik4u** » Mon Jul 10, 2006 4:33 am

Cruise should actually HOLD the convertor locked a bit longer (allow more TPS before unlocking).....I'll double check this afternoon to make sure.

Sounds like the rest is doing well though.

daevans315 · Post by **daevans315** » Tue Jul 11, 2006 12:43 pm

New flash in original PCM installed. No check engine soon light. No change in shift points after grounding Pin 71.... I'm going to run the wire inside the cab and wire the switch back up... just to make sure it isn't something that has to be done when in Drive or turns off when you open the door... (nothing I read says that it does but ...... I'm grasping at straws here).

EDIT **** No change when grounding while driving.

daevans315 · Post by **daevans315** » Wed Jul 12, 2006 8:36 am

I have Googled the hell out of this and come up with one more remote lead. I downloaded the entire LS1edit.com mailing list archive(44mb of raw text) and started searching it. There are people doing this here and there on the list but only one email I thought might help.

Al,

The Holden models here in Australia as Ken said, do have a switch for 2
different Transmission modes..
Having a look at the PCM schematics its a simple case with our calibrations
(Same for US cars ??) of earthing Pin J1-71 (Blue Connector) to switch
modes..
The factory here installs a simple on/off rocker switch, with of all things
p and e on it.. Plus we have a dash light that says "POWER"
when PCM is in that mode.. Trendy eh

Now given this is an Australian F-body car, but I might gleam from this that it needs a continuous ground to work? The rocker switch comment is where I'm pulling that. There are momentary contact rockers that just contact as they flip over but that is not the most common type.

I think I’m going to give this one last stab but I’m about ready to admit defeat.

Post by **Walt** » Wed Jul 12, 2006 8:53 am

daevans315 wrote:I have Googled the hell out of this and come up with one more remote lead. I downloaded the entire LS1edit.com mailing list archive(44mb of raw text) and started searching it. There are people doing this here and there on the list but only one email I thought might help.

Al,

The Holden models here in Australia as Ken said, do have a switch for 2
different Transmission modes..
Having a look at the PCM schematics its a simple case with our calibrations
(Same for US cars ??) of earthing Pin J1-71 (Blue Connector) to switch
modes..
The factory here installs a simple on/off rocker switch, with of all things
p and e on it.. Plus we have a dash light that says "POWER"
when PCM is in that mode.. Trendy eh
Now given this is an Australian F-body car, but I might gleam from this that it needs a continuous ground to work? The rocker switch comment is where I'm pulling that. There are momentary contact rockers that just contact as they flip over but that is not the most common type.

I think I’m going to give this one last stab but I’m about ready to admit defeat.

Kinda aggravating that other countries get all the good stuff

Jigg · Post by **Jigg** » Wed Jul 12, 2006 8:55 am

My bet goes with having the pin grounded continuously. I was under the impression that's what you were doing all along.

daevans315 · Post by **daevans315** » Wed Jul 12, 2006 1:28 pm

No change with a continuous ground either. I did find this post

http://www.zr2usa.com/mboard/index.php? ... 2726&st=15

Somebody has gotten it to work in an s-10 truck. So its either the PCM programming isn't right or my pin ground is bad. I'm going to take one more good look at the pin in the plug and see if I can get something in there to check continuity from the female part of the pin back to ground.

daevans315 · Post by **daevans315** » Mon Jul 24, 2006 10:22 am

The tow haul button continues to taunt me. I rented a U-haul over the weekend. 17' box truck on a ford chasse. It not only had the tow haul button but it defaulted to on, you had to turn it off every time you started it if you didn't want it. It worked great in the loaded uhaul running some hills. Its a rental, its a Ford, and it still works better than mine.

I'm done.

2kwik4u · Post by **2kwik4u** » Mon Jul 24, 2006 11:33 am

Wonder if there is any chance of PCM4Less sending you the bin file he put on your PCM. I seriously doubt it as thats the intellectual info that he is selling, I can't imagine him giving it away for free. If I had it I could verify that bit was or wasn't changed.

Thanks for the trial and error on all this. Is the tune at least working well for you otherwise?

daevans315 · Post by **daevans315** » Tue Jul 25, 2006 7:24 am

Ok.. now we are getting some where. I found out you can download a demo copy of EFILive that will let you load and edit files, just not save or flash your changes. I found stock 2002 s-10 tune and took a screen shot of EFILive's "button" to change the setting from "serial Bus" to One Switch and sent it to Bryan. Here is what I got back. I'm a little frustrated with him now but at least this is progress.

Let me forward this to the guy that makes the software I use and see if he can find this table as it is not offered with my software that I use.
Bryan

Other than this, the tune is definitely a change. It takes a while to come on but once it gets out of learn mode I picked up some HP and much nicer shifts. If I had known what a differance removing the timing pull from the shifts I might not have been looking so hard for the tow\haul button.

2kwik4u · Post by **2kwik4u** » Tue Jul 25, 2006 7:48 am

daevans315 wrote:Ok.. now we are getting some where. I found out you can download a demo copy of EFILive that will let you load and edit files, just not save or flash your changes. I found stock 2002 s-10 tune and took a screen shot of EFILive's "button" to change the setting from "serial Bus" to One Switch and sent it to Bryan. Here is what I got back. I'm a little frustrated with him now but at least this is progress.

Let me forward this to the guy that makes the software I use and see if he can find this table as it is not offered with my software that I use.
Bryan

Other than this, the tune is definitely a change. It takes a while to come on but once it gets out of learn mode I picked up some HP and much nicer shifts. If I had known what a differance removing the timing pull from the shifts I might not have been looking so hard for the tow\haul button.

SHould've said something....I have that software, and could've had you a screenshot in minutes before

No biggie though I suppose.

Glad to hear the tune itself is working well for you otherwise though.

S-10CREWCAB.NET

Tow/Haul button......and Auto 4wd

Tow/Haul button......and Auto 4wd

Re: Tow/Haul button......and Auto 4wd