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

Post by **HenryJ** » Sat Feb 07, 2009 7:33 am

You might be right. Still worth a shot though.

04crewvt · Post by **04crewvt** » Sat Feb 07, 2009 7:42 am

Certainly, especially since the junkyard parts will be less than reprogramming will cost. I just found this stuff out while surfing the issue and figured it was better to give a heads up to all. It is sort of amazing how much these newer vehicle "talk" to themselves and to others if you have the means to read them much more than the OBD codes that most think of. Wish I could afford the TechII scanner to keep up with all this stuff.

green02crew · Post by **green02crew** » Sat Feb 07, 2009 8:00 am

Hmm interesting, so what is the procedure for resetting the SDM?

Post by **HenryJ** » Sat Feb 07, 2009 8:08 am

Tech II scan tool, but that may not be a possibility either as the tech is unable to flash for other than what is provided to them.
I'll ask some questions Monday, but I do not have confidence in the experience of the techs available.
I am pretty sure they will not look for answers, only say it can not be done.
If we need to match the BCM VIN , that may not be an option as the PCM is the original. If the SDM will accept the BCM VIN, then it might be OK.
Lots of unknowns. I am not sure I have a tech here that is smart enough to do this. I sure wish I had access to a Tech II. I just can not justify $3200 though.

04crewvt · Post by **04crewvt** » Sat Feb 07, 2009 8:12 am

We need to start a TechII fund and share. Split the cost and then ship it to who needs it.

Post by **HenryJ** » Sat Feb 07, 2009 8:35 am

Rrrright...find a hundred people at $35 each? Might have a better chance buying a lottery ticket.

Actually I would rather get LS1edit first.

The best option would be to get friendly with a local tech who has access to a Tech II. Our local dealer closed shop and moved out of town. long distance relationships are not as close.

04crewvt · Post by **04crewvt** » Sat Feb 07, 2009 8:40 am

Yea then we would just need to each by our own license copy and cable..

Post by **HenryJ** » Mon Feb 09, 2009 11:38 am

UPDATE:
Called the dealer. The tech did not know if the TechII would be able to change the module ID. He said they could try it, but had never done it. Cost $42 -$84

I grabbed the SDM from the Jimmy my BCM came from. It did have airbag deployment. The service manual shows the SDM as well as all the sensors and modules being replaced after a deployment.
The guys at the salvage yard did not know if it would be any good now. I don't either. I guess all I can do is try it. I might get time on a weekend in the next couple weeks.

EDIT: Took the time to install the SDM tonight as the rest of the week is looking full.
No difference.
Either it is bad and a new problem, or this is not going to be the fix. I tend to think the latter.
Back burnered for now.

PonyKiller · Post by **PonyKiller** » Thu Feb 12, 2009 12:03 pm

I picked up a BCM and tow/haul switch from a junk yard in Peoria, IL this weekend. Probably one of my best junk yard buys in a while, got 6 way power leather buckets for my fullsize truck for $40 each and he threw in the BCM for free because he didn't know what was and figured nobody else wanted it, lol.

I am planning on installing it this weekend, putting the switch in the top of the blank next to the radio. It didn't look like the air bags were deployed on the bravada that I got the parts out of but we will see if the light comes on or not.

If the light does come on I have a friend that is a teck at the local dealership here and I'm sure he would be willing to borrow a techII to figure it all out and get the light turned off.

Post by **HenryJ** » Thu Feb 12, 2009 2:42 pm

If you end up using the TechII be sure to fill us in step by step so that we can lead the techs here through it.

PonyKiller · Post by **PonyKiller** » Sat Feb 14, 2009 7:29 pm

WTF!

I swapped out the BCM, installed the switch, did the relearn..... I now had the air bag light, the tow haul button lights up but it doesn't do anything when you hit it. Light in the dash doesn't come one and shifting doesn't change at all. Anyone have any ideas?

Oh yeah its a 03 Zr5 with pretty much all the options.

Post by **HenryJ** » Sat Feb 14, 2009 7:38 pm

Check the wires. Make sure the blue wire is getting grounded.

Slow down , go back and triple check all the connections.

kenfyoozed · Post by **kenfyoozed** » Fri May 14, 2010 1:59 pm

I know this may be digging up an old thread but I thought it best to be put here.

How much does the tow/haul help?

I have towed my Massey Ferguson 135 tractor with a bushhog and boxblade, on a tandem axle 16' trailer and my CC had no problem shifting or keeping the gears below 55. Above 55 is where the problem lies for me. Even when towing an unloaded 12x5 trailer at 65 through hills my CC likes to shift alot between 3rd and 4th. Flat ground I dont seem to have a problem unless I am towing over 55 with a very very heavy load, like the tractor.

Im clueless wehn it comes the electrial parts of our rides, but isnt there a device that is plug and play to change the shift points for our trannys. Couldnt something like this be programmed the same way and then be turned on and off? Or am I way off base?

Post by **HenryJ** » Fri May 14, 2010 2:26 pm

kenfyoozed wrote:How much does the tow/haul help?

Having recently completed a fairly long journey with the tow haul, I'd say it really does help quite a bit. It hold the shift substantially longer. On the down grades it holds the gear and seems to help with some engine braking. I did not use it 100% of the time, but it was noticeably better when I did need it.
The transmission showed the difference too. It ran cooler in tow mode.

Im clueless wehn it comes the electrial parts of our rides, but isnt there a device that is plug and play to change the shift points for our trannys.

The HPPIII does adjust shift points. It works mostly at full throttle, however you can set the 3-4 shift point about 12 mph higher and get it to quit stutter shifting back and forth while pulling a slight grade. Paul and I both did that. I was able to get somewhat better shifts in the other gears too, but the shift firmness setting may play more of a part there. I would not live with out that. It is the biggest reason TO get a HPPIII.

Couldnt something like this be programmed the same way and then be turned on and off? Or am I way off base?

Perhaps. I think installing the tow/Haul BCM and switch is the easy way to do that. It works for me.

kenfyoozed · Post by **kenfyoozed** » Fri May 14, 2010 4:20 pm

But doesnt this mod disable the airbags?

If so then this mod is going to work for me.

Post by **HenryJ** » Fri May 14, 2010 6:19 pm

kenfyoozed wrote:But doesnt this mod disable the airbags?

The "mod" doesn't, however if you do not have the BCM programmed to match the vehicle, then yes the SRS light is illuminated. Mine is as I have never had that done and usually wheel with the fuse pulled anyway.

LoneWolf04 · Post by **LoneWolf04** » Tue Nov 08, 2011 2:29 pm

Digging up this thread again because I had a question about the swap. HenryJ, what gears did your truck have in it from the factory? I ask because mine has the optional 3.73 gears in it and finding a BCM with the GT4 code and tow/haul function is like a needle in a haystack. Im not sure if the gearing is located in the BCM or PCM but I did not want my speedo to be off by installing a new BCM with the wrong gearing code in it if thats where the information is stored.

I may have found a way to get the air bag light off when doing this mod. Recently my SDM module failed and needed replacement and I purchased one. After replacing the SDM it needs to be reprogrammed with the the VIN in the BCM so you do not get the B1001 mismatch code. In order to do so you actually need to do a relearn for the keyless entry system. When doing so a command is triggered to the SDM to gather the vin from I believe the BCM so there is no longer a mismatch code.

I will be trying to perform the mod this weekend if I have time and if I can pair the BCM and SDM modules I am hoping the air bag light will go off. I will update this as soon as I know.

Post by **HenryJ** » Tue Nov 08, 2011 3:32 pm

Mine also had the 3.73 gear ratio. I do not believe that the BCM is involved in that aspect as I am able to change the ratio and tire size in the PCM using a tuner.

It would be great to hear that you found a way to turn off the light. That would help out a couple with their lights still on for sure.

green02crew · Post by **green02crew** » Thu Nov 10, 2011 4:35 am

I would be happy to have that figured out as well. I'm still holding onto my stock BCM for the day it's traded so the airbag light will be off. I would love to ditch some old parts from the collection! I also don't think the BCM has anything to do with gearing.

Post by **HenryJ** » Thu Nov 10, 2011 7:37 am

green02crew wrote:I would be happy to have that figured out as well. I'm still holding onto my stock BCM for the day it's traded so the airbag light will be off. I would love to ditch some old parts from the collection! I also don't think the BCM has anything to do with gearing.

Bad news...the old BCM will no longer turn off the SRS light. I had the same plan and kept my stock BCM. I swapped mine back in before trading it in and the light remained on. I saw no sense in that so I put the tow/haul BCM back and let the new owner figure out how to turn the light off with a visit to the dealer for a flash to match the VIN.

LoneWolf04 · Post by **LoneWolf04** » Wed Nov 16, 2011 5:21 pm

Well nothing to report yet. I was hoping I could flash I myself but don't have clearance. Will have to get someone over to eventually try to flash it, still haven't even had time to get the mod done. Will report back when time permits.

booth9c1ss · Post by **booth9c1ss** » Mon Feb 27, 2012 12:56 pm

I'm re-visiting this topic.

I recently got a 2002 ZR2 pickup (with 233 and and automatic transmission). Since there was/is a lot of discussion here on this mod, I thought I'd check it out. I actually helped contribute to this thread on page two (I was Steventruck... but I couldn't get my username/pw to work) years ago.

I had another BCM laying around but I couldn't get the truck to accept it. I went through the security re-learn 10-min thing three times, and the security light went out... but the truck wouldn't start, and after the third attempt the security light remained on solid. I swapped back to the original BCM.

My original BCM has RED and GREEN exposed. No fogs, No T/H, the DRLs stay on with the turn signal.

The donor BCM has ORANGE exposed. Fogs, T/H, i couldn't get the DRLs to work to test the turn feature.

The BCMs that originally came in my wife's 2000 blaZeR2 and my 99 ZR2 (manual trans) pickup were both RED exposed only. Neither had fogs.

Have you guys figured out what the color codes are for? I'm not willing to give up the safety of SIR to have this mod, yet.

Steve

Post by **HenryJ** » Mon Feb 27, 2012 1:27 pm

I really don't think it went farther. I never have heard if they were able to VIN match the BCM with a flash at the dealer. I never did get my hands on a TechII before I sold my truck. Mine sold with the light still on.
I am still convinced that was all that was needed. No different than installing a new BCM? However, It is possible that only a new BCM can be flashed, and it may only accept one VIN. If that is the case, we are "hosed".

booth9c1ss · Post by **booth9c1ss** » Mon Feb 27, 2012 3:21 pm

Dealer rate is $80/hour. How much is a new BCM? I wonder if they car reflash (but not alter vin stuff) or current BCMs and just add the fog light control and tow/haul.

Post by **HenryJ** » Mon Feb 27, 2012 3:27 pm

Seems like the BCM was around $250 for a new one, but that has been a while and I may be mistaken. The correct BCM comes with the needed features if I understand it correctly. The dealer does the "VIN" match once it is installed. This is so the PCM and TCM recognize each other?

I have had the dealer install one new one on a fleet rig. It could not be powered up until the TechII was connected. If it was powered up and moved , you had to buy another one as it could no longer be flashed. That one had the speedometer functions in it IIRC.

LoneWolf04 · Post by **LoneWolf04** » Tue Jan 01, 2013 8:59 pm

Well I finally got around to installing this BCM and tow haul button. I apologize for taking a year to finally put this in. Everything works great except the B1001 code that comes up. I noticed while looking through GM ESI that it spefically states when an SDM is replaced to NOT use the 30 minute manual procedure to relearn the theft deterrant system. My guess is doing the manual procedure does not initiate the VIN # transfer from the BCM to the SDM so you do not get the mismatch code. Only way is to have a tech 2 and have it hooked up to their techline terminal. I do have someone that has it available to do this, but am unsure how long it will take him to get around to doing this favor for me. I will write a follow up if this takes care of the issue. I'm hoping by doing the manual relearn I did not fry the SDM since it states not to do the manual procedure, that would be my luck though.

Post by **HenryJ** » Tue Jan 01, 2013 9:13 pm

Go! GO! GO! You are doing great. I wish I had been able to complete this.

Jongo88 · Post by **Jongo88** » Wed Jan 02, 2013 1:18 am

I have the tow/haul working in my truck... We have a tuner guy on my other forum that can hook you up. There is no need to change out the BCM eather....

Indigo04 · Post by **Indigo04** » Wed Jan 02, 2013 7:30 pm

Keep going and do explain please.

Jongo88 · Post by **Jongo88** » Thu Jan 03, 2013 12:47 am

Whats to tell?? You send him your PCM and he can make it do just about anything you want. I sent him mine for a tune and he added the tow/haul to it. I picked up a tow/haul switch from the junk yard ran one wire to the PCM and bingo. I have a tow/haul.

Post by **HenryJ** » Thu Jan 03, 2013 5:52 am

Jongo88 wrote:Whats to tell?? You send him your PCM and he can make it do just about anything you want. I sent him mine for a tune and he added the tow/haul to it. I picked up a tow/haul switch from the junk yard ran one wire to the PCM and bingo. I have a tow/haul.

Ok, there is a little more to it than that.
What wire did you run? You wired a switch, but to do what? Got pics?

Is your MIL illuminated? Or just a stored code?

It seems strange to me that you can bypass the BCM, but if you have it working, that is what counts. Your dash light works correctly?

LoneWolf04 · Post by **LoneWolf04** » Thu Jan 03, 2013 10:27 pm

Even though I got my truck running I was informed to stop driving it. Apparently after so many ignition starts either the BCM or SDM will lock out and when he gets over to program it he wouldn't be able to if I kept driving it (driving the winter beater right now anyways). Luckily I only have started it about 4-5 times since installing. He was supposed to make it over today but got held up. Next appointment date is Monday hopefully.

Jongo88 · Post by **Jongo88** » Fri Jan 04, 2013 1:01 am

No dash light. For that you need the BCM. I forget which pin it is. He sent a 6 inch wire with the female pin that I had to install into the PCM plug. The wire then goes to the tow/haul switch. The other side of the switch wire goes to ground. When you push the switch it changes to the other trans tune. On mine he programmed it to shift at a higher rpm and firmer. You push it again and it goes back to the other tune. I would say stock but I had him firm it up too.
With the tow/haul and the B&M I have 6 shift patterns.

Post by **HenryJ** » Fri Jan 04, 2013 8:18 am

Jongo88 wrote:No dash light. For that you need the BCM. I forget which pin it is. He sent a 6 inch wire with the female pin that I had to install into the PCM plug. The wire then goes to the tow/haul switch. The other side of the switch wire goes to ground. When you push the switch it changes to the other trans tune. On mine he programmed it to shift at a higher rpm and firmer. You push it again and it goes back to the other tune. I would say stock but I had him firm it up too.
With the tow/haul and the B&M I have 6 shift patterns.

Ah, makes more sense now. I suspect that it is more shift firmness than a true tow/haul mode mapping.
I could be wrong, but I was under the impression that it is the BCM that stores the maps for tow/haul?

I would still like to see a BCM with Tow/haul VIN matched to a crew cab.

I believe that I still have my stock BCM with no tow/haul on the shelf. I am pretty sure you are right about a number of ignition cycles locking it out. I tried swapping mine back to turn off the MIL, but it had no effect. I had gone too long and there was no going back.

_STUCKY · Post by **_STUCKY** » Fri Jan 04, 2013 9:19 am

So I can get the tow/haul function added in when and if I ever send my PCM off to get tuned?

http://www.pcmforless.com/
http://wait4meperformance.com/

LoneWolf04 · Post by **LoneWolf04** » Fri Jan 04, 2013 9:26 am

If you are looking for the true tow/haul mode then no. The only way to achieve that is to get a bcm from a blazer that has it and install it in your truck. Come Monday I hope to have the solution to the airbag light (B1001 code) issue resolved. It sounds that if you want it programmed, you'll want to drive it up to your dealer with the factory bcm and once they get it into the bay swap it and have them do a theft deterrent relearn with gm techline. I will post more once it is available.

Post by **HenryJ** » Fri Jan 04, 2013 9:44 am

The issue I saw with having the dealer reprogram the BCM is that they will VIN match it. Our VIN had no option for the tow/haul. Does that erase the tow/haul mode in the donor BCM?
I never did get a dealer Tech that could answer that for me.
They can not alter a vehicle beyond OEM programming with the TechII. It just doesn't work like that.
I never did have a friend close enough with access to a Tech II to play around with matching up a Bravada tow/haul BCM in my old truck. It would have been a roll of the dice. If it didn't work I might have ended up with a stock BCM again. I really liked the tow/haul option and didn't feel like paying for the chance to lose that just to get the airbags working again and the MIL off.

LoneWolf04 · Post by **LoneWolf04** » Fri Jan 04, 2013 10:04 am

They aren't reprogramming the BCM though. They are only doing a theft deterrent relearn procedure (like the manual proceudre you have to do to get the truck to start up after the BCM swap) doing it with the tech 2 it also updates the information in the SDM, where the mismatch B1001 code is coming from. It will not erase anything out of the BCM. This is what I have gathered and the guy I am talking to about this is one of the smartest guys I know that works behind the scenes at GM. He does a lot of work with the dealers when the parts changers can't figure out what's going on.

Did you have a MIL on too Henry? The only thing I have on is the airbag light.

In any case, as soon as I have a day off and this guy is in town I will be hopefully resolving this.

LoneWolf04 · Post by **LoneWolf04** » Mon Jan 07, 2013 8:05 am

Well today will not be the day for the tow/haul fix unfortunately... Guy had to go to out of town for work. Sounds like either wednesday or possibly all the way til next week

Still promising, just was hoping to get it set up and give everyone a definite answer on a solution. Will keep everyone posted.

LoneWolf04 · Post by **LoneWolf04** » Wed Jan 09, 2013 10:22 am

UPDATE!!!!

For everyone wanting to install a blazer BCM into your crew and have tow haul, the air bag light will now be off. The Mods page to this forum will need to be updated as well in order to reflect what needs to be done.

I was able to get my theft detterant system relearned today using the GM scan tool method. I believe the module they use is called the MDI, don't quote me on this because I was more paying attention to the truck and talking the guy about other subjects. In any case, he went through the 10 minute relearn procedure for the theft detterant system which indeed made the SDM relearn the VIN information from the BCM and take care of the B1001 code you will get with only doing a manual key on - key off relearn to start the truck. My airbag light is not on anymore and no other systems have fault. Everything is functioning well together and there is now a solution to the problem!

My suggestion for anyone wanting to do this is to replace the BCM at home and do a manual key on - key off relearn. Immediately after it starts I would take it up to the dealer (I would have an appointment ready). Inform them you need to have the vehicle's theft deterrant system relearned using the scan tool and have the codes cleared out of the supplemental restraint device. This way you aren't looking shady as far as swapping a part out in the service lane when youre pulling up and your vehicle will also be able to start.

Post by **HenryJ** » Wed Jan 09, 2013 12:37 pm

What is the key on - key off relearn? This solves the airbag light issue?

LoneWolf04 · Post by **LoneWolf04** » Wed Jan 09, 2013 12:43 pm

The key on- key off relearn was so you can start your truck. It is the 30 minute relearn process because the theft deterrant will not allow the vehicle to start when the BCM is swapped from the original to the one from a blazer. That does not solve the airbag issue. You have to drive your truck up to the dealer after getting it to start and have them do a theft detterant relearn with their scan tool. The relearn with the scan tool initiates a few other functions between the BCM and SDM modules in order to solve the B1001 mismatch code (Airbag light).

Post by **HenryJ** » Wed Jan 09, 2013 12:59 pm

Do you have the steps involved in the relearn?

LoneWolf04 · Post by **LoneWolf04** » Wed Jan 09, 2013 1:08 pm

The GM scan tool relearn? No. They have to have it logged into there system. The guy did not use a tech 2 to do it. Had a program on his laptop he had to launch and log into. So this relearn to get the airbag light off is not a DIY option. You will have to go to the dealer which if they're nice they shouldn't charge more than 1/2 hour labor because the relearn with their system only takes 10 minutes plus plugging it in. No more than 20 minutes total.

The relearn to get it running is posted in the mods page. Try to start let sit on for roughly 10 minutes, security light will flash and when it stops flashing turn key to off position and repeat steps 2 more times for a total of about 30 minutes.

*EDIT*
After loading the program he selected year, make, model of the vehicle. Once that selection had been made it asked which programming function you want to do. You pick Theft Deterrant System" and hit ok. It will ask to verify the VIN brought up matches the VIN on the door, which it did. Once you accept it, it begins the relearn process. Once the process is complete it asks to turn the vehicle to the off position for 30 seconds. After the 30 seconds you start the vehicle and it will start and you will notice your airbag light will be off. You will want to the dealer to go in and clear out the history code that is left from having the airbag light on though once the relearn is complete.

Jongo88 · Post by **Jongo88** » Sat Jan 12, 2013 5:18 pm

Sounds like a major pain just to get the stock tow/haul mode with the torque management still killing your performance. . I like it programmed to what ever you want it to do. I have the stock switch but my tow/haul does exactly what I want. And the best thing it is plug and play.

Post by **HenryJ** » Sat Jan 12, 2013 5:40 pm

So, lets put it all together for the OEM install.
All the pieces and tools needed. All the steps. All the parts. Maybe I can get a page put together?

It really is an easy swap and install. All the stock stuff is there. Nice to have it work just as it does from the factory.

Thanks for taking the time to figure it all out! Sure wish I knew where my old truck was to pass along what they need to do to turn that light off.

LoneWolf04 · Post by **LoneWolf04** » Sat Feb 23, 2013 12:15 pm

I will try to get a write up together for an OEM install. I will probably base part of it off the wrote up already done in the Modifications section and add in what needs to be done in order to turn off the air bag light.

On another note, this past Thursday was the first time towing with the crew and I must say I was very impressed with everything. I live in Grand Blanc, MI and towed a two place inline snowmobile trailer up to Grayling for a day trip. trailer is tandem axle and weighs 1900lbs unloaded, so guessing around 2700lbs loaded. I averaged 10.3MPG round trip going 65MPH in 3rd. Trans temp only got between 120 and 125F. I also used mid-grade fuel to make sure no engine pinging would occur on hills. There wasn't too much wind either so I know that will be a factor in economy as well. It basically took a tank in each direction. Low fuel light would turn on when arriving to my destination.

Modifications I've got on the truck that would affect mileage:
-tow/haul feature, which works great.
-b&m trans cooler
-Goodyear duratrac tires, decently aggressive all-terrain tire.
-full magnaflow exhaust since my converter went out over the summer.
-fiberglass topper

I was shocked at the mileage I got out of the truck. It was actually more mileage than my dad would get towing with his '03 silverado 1500 4x4 with a 5.3L in tow haul using 3rd going 70MPH. No mods done to the truck except BFG All-Terrain tires. He would average just below or over 9MPG.

Next on the to-do list is rear springs. Going to try and get rid of a little of the rear squat with the trailer. Considering the Boise Spring mod. I felt pretty confident pulling the trailer as it felt very connected the road. Just thought I would share the experience. Plan on making the trip again on Tuesday.

S-10CREWCAB.NET

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

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