Torque Converter Control

Post by **HenryJ** » Sat Jul 24, 2004 1:19 pm

I installed a TCC switch today.

This all started from a thread on another forum where someone is needing to diagnose what could be a torque converter lock-up problem.

I have a friend who's first generation Blazer had a problem with locking and unlocking at some cruise speeds. We installed a toggle switch to disable the converter lock-up. He has been really happy with it.

Now, I wondered if the same thing could be done with newer models...of course where there's a will there's a way!

It is actually pretty simple:

The wire for the TCC is the purple wire in the brake light switch. Don't get excited , but there are twin purple wires on the same connection for those who have cruise control. So we will be disabling the cruise control in the same process.

It is normally a closed connection. When the pedal is depressed the connection is open. Installing a switch to break the connection should do the trick.

Take the retaining clip off the master cylinder pushrod , to remove the brake switch.
Now unlatch the plug for the wiring, pop loose the retaining clips from both ends and pull the purple wires female connector out.

I inserted a spade into this connector and ran that to the new switch, and from the switch back to a new female connector that I reinserted into the brake light switch connector.

Reassemble everything.

I mounted my switch (a salvage yard rocker light switch from a Blazer) to the panel that I removed for access to the brake light switch.

This is easily reversible since no connections were cut.

*Warning* This is as of right now untested. I will test it tomorrow on an all day trek.

Rusty · Post by **Rusty** » Sat Jul 24, 2004 2:50 pm

Any way to tell which purple wire does the cruise and then just cut and splice the other one?

Post by **HenryJ** » Sat Jul 24, 2004 3:00 pm

GaryH wrote:Any way to tell which purple wire does the cruise and then just cut and splice the other one?

Yes , but that would not be as easily reversible.

I want to make sure it works as planned.

If I like it ... I'll try one wire , see if the cruise quits or , the converter unlocks, pick the right one and just hook that one to the switch.

Heck I have a 50/50 chance of getting the right one the first time and the wrong one won't do any damage.

Rusty · Post by **Rusty** » Sat Jul 24, 2004 4:34 pm

HenryJ wrote:
GaryH wrote:Any way to tell which purple wire does the cruise and then just cut and splice the other one?
Yes , but that would not be as easily reversible.

I want to make sure it works as planned.

If I like it ... I'll try one wire , see if the cruise quits or , the converter unlocks, pick the right one and just hook that one to the switch.

Heck I have a 50/50 chance of getting the right one the first time and the wrong one won't do any damage.

Either way, it's got to be easier than trying to find the right wire out of that bundle that goes into the tranny. I was thinking about that but decided against it after seeing the wiring harness. Can't wait to hear how this works!

smokinjoe · Post by **smokinjoe** » Sat Jul 24, 2004 5:17 pm

im a little slow, but what does unlocking the torque convertr do, what is the purpose?

Jim · Post by **Jim** » Sat Jul 24, 2004 6:52 pm

On my ElCamino I connected a relay to the switch for the cruise control, cruise off TCC off... Cruise control switch in the on position would cause it to work normal. Do you think that could be done on the Crew Cabs?

My son's S-10 w/2.2 in it wavers in & out of lock up at certain speeds...really annoying.

P.S. I

my TCC it makes my truck feel like its real under-powered at times.

Post by **HenryJ** » Sat Jul 24, 2004 7:18 pm

smokinjoe wrote:...what does unlocking the torque convertr do, what is the purpose?

The converter locks primarily for gas mileage reasons. It takes a specific amount of throttle or brakes to unlock.
Some have had it lock, unlock, lock, unlock while pulling hills or towing. This will prevent that issue.

Post by **HenryJ** » Sun Jul 25, 2004 7:42 pm

HenryJ wrote:I installed a TCC switch today....
*Warning* This is as of right now untested. I will test it tomorrow on an all day trek.

Tested and works just fine!

Jim · Post by **Jim** » Mon Jul 26, 2004 2:20 am

HenryJ wrote:
HenryJ wrote:I installed a TCC switch today....
*Warning* This is as of right now untested. I will test it tomorrow on an all day trek.
Tested and works just fine!

I plan to do this mod ASAP but i'm going to try to use the cruise on /off switch to activate a relay to do the switching.

quickbiker · Post by **quickbiker** » Mon Jul 26, 2004 2:32 am

So, does this switch lock it solid if ya want or just shut off the locking ability? Be nice to lock it solid.

Post by **HenryJ** » Mon Jul 26, 2004 3:54 am

quickbiker wrote:So, does this switch lock it solid if ya want or just shut off the locking ability? Be nice to lock it solid.

shuts off the locking ability.

When you pull a hill and the engine bogs way down at partial throttle , flipping the switch unlocks the converter and you pick up a few more rpm. A couple times it made up for what would have been a downshift.

It is not something that I will need all the time, but may come in handy.

badandy2003cc4x4 · Post by **badandy2003cc4x4** » Mon Jul 26, 2004 10:37 am

by disabaling the cruise dose it disable the cruise all the time or only when the lock up is disengaged (switch flipped)?

Post by **HenryJ** » Mon Jul 26, 2004 1:04 pm

badandy2003cc4x4 wrote:by disabaling the cruise dose it disable the cruise all the time or only when the lock up is disengaged (switch flipped)?

Only when switch is flipped.

Jim · Post by **Jim** » Mon Jul 26, 2004 6:33 pm

Almost ready...

I found this laying around (i never throw any stuff like this away)

Love these German parts the pin diagram is on the side of the case.

Post by **HenryJ** » Mon Jul 26, 2004 7:03 pm

Jim wrote:Almost ready...

Do you have the wiring diagrams?

here is a little (very little help)-

On the multifunction switch:

GRY= cruise control on switch signal
BRN= power from fused power distribution
DK BLU= cruise control set/coast switch signal
GRY/BLK= cruise control resume/accel switch signal

All the above go to the cruise control module in addition to the following:

BLK/WHT= ground
LT BLU= hot with brake applied, CHMSL supply voltage

Looking further into the purple wire from the stop lamp switch, it appears that the ABS system may somehow be affected also, how? I don't know yet.

2bunik · Post by **2bunik** » Mon Jul 26, 2004 7:09 pm

I must be slow too. but I can't seem to understand either.. I was under the impression that a stall converter would wind till a certain rpm was achieved then lock up and start the power transfer process.. Now a torque converter is always locked causeing the power to be transfered as soon as the vehicle is put into drive..
SOMEONE correct me please...

Post by **HenryJ** » Mon Jul 26, 2004 7:50 pm

2bunik wrote:...correct me please...

You have the right idea.

a "standard" torque converter has only a stall rating. That is the calculated rpm for a given torque and horse power where if the vehicle was unable to move it would theoretically stall the engine.
Example: trans locked, 4000 rpm stall converter would stall the engine at 4000 rpm. Slipping all the way at rpms below that point.

While this works well for transferring the power to the drive train, it does nothing for gas mileage with all that slipping going on at lower engine speeds.
That is where the locking converter comes in. It is electronically locked at partial throttle cruise speed.

That is that extra shift you feel in the top end. count the shifts you feel some time and you'll see a 300 rpm drop and what feels like another shift after overdrive. That is the converter locking.

Jim · Post by **Jim** » Tue Jul 27, 2004 7:03 am

Maybe I'm not ready. I've been reading to much. I planed to not use the TCC for days, but it looks like keeping it off will set DTC's.

Rusty · Post by **Rusty** » Tue Jul 27, 2004 8:42 am

Oh well, I guess I'm back to manually downshifting to 3rd when the lockup converter starts annoying me. D***ed computer controlled vehicles (actually, d***ed OBD-2 or whatever version they're up to now)!

Jim · Post by **Jim** » Tue Jul 27, 2004 11:47 am

GaryH wrote:Oh well, I guess I'm back to manually downshifting to 3rd when the lockup converter starts annoying me. D***ed computer controlled vehicles (actually, d***ed OBD-2 or whatever version they're up to now)!

"I'm sorry, Dave, I'm afraid I can't do that."
-- HAL 9000, 2001: A Space Odyssey

I didn't Know we were dealing with HAL, but it almost seems like it

Post by **HenryJ** » Tue Jul 27, 2004 2:01 pm

Jim wrote:...I didn't Know we were dealing with HAL, but it almost seems like it

I know exactly how you feel, but there are ways to fool "IT" into a false sense of reality

Jim · Post by **Jim** » Wed Jul 28, 2004 8:27 am

I really wanted to do this mod, as you can see I did it on my wife's Corvette 20 some years ago.

Brad · Post by **Brad** » Fri Oct 08, 2004 6:28 pm

Would this allow for towing light loads in overdrive?

Brad

Brad · Post by **Brad** » Sat Oct 16, 2004 6:59 pm

Hello.

Post by **HenryJ** » Sat Oct 16, 2004 7:12 pm

Brad wrote:Hello.

Sorry, missed that post

I don't think it would be a good idea to be towing in anything other than 3rd gear.
Overdrive is just that, running faster than the engine rpm. It is designed to maintain speed at a lower rpm. Not designed to handle a load.

The TCC will help on those long grades where the converter locks rpm drop too much, so it unlocks and downshifts, then upshifts locks the converter, and repeats the process.

We have a couple long grades like this outside of town. Unlocking the converter stops the rpm drop and maintains speed enough not to have to downshift.

eugene · Post by **eugene** » Sat Oct 16, 2004 7:41 pm

I have always heard/read that an unlocked TCC creates more heat, might want to add a temp gauge, mine runs too hot stock.

Post by **HenryJ** » Sat Oct 16, 2004 7:59 pm

eugene wrote:I have always heard/read that an unlocked TCC creates more heat, might want to add a temp gauge, mine runs too hot stock.

That sounds reasonable.
I suggest that everyone add an aux. cooler anyway

eugene · Post by **eugene** » Sat Oct 16, 2004 8:11 pm

I'm still trying to find room to put a cooler

I know I need it though after about 30 minutes of driving the gauge hits 250.

adrenalnjunky · Post by **adrenalnjunky** » Sat Oct 16, 2004 10:50 pm

Transmission Cooler Mod

eugene · Post by **eugene** » Sun Oct 17, 2004 5:40 pm

The center support on mine is different so I can't fit a cooler in front of the radiator.

Post by **HenryJ** » Sun Oct 17, 2004 5:55 pm

eugene wrote:...I can't fit a cooler in front of the radiator.

Awww, that's not true.
Trans coolers come in many different sizes. Some as small as 2.5"x7.5".

Measure the space that you have from the center support to the right side of the core. Then just get one that fits that area.

That is what I did , and I bought my "sandwich style" cooler kit for $50.

aa21830 · Post by **aa21830** » Thu Mar 10, 2005 12:15 pm

Rusty wrote:Any way to tell which purple wire does the cruise and then just cut and splice the other one?

Yes...cut one wire, then go for a drive and see if your cruise control still works

Actually, that's just what I did and guessed right the first time. Here's what it looked like in the harness:

I cut the lower of the two wires, and that one turned out to be the TCC wire (good guess, thank you very much!

). I'd assume all the harnesses were assembled the same way.

The only weird thing is that when I start the engine, the ABS light comes on. When I flip the TCC switch off and on, the ABS light turns off and stays off. Other than that, it's been a great mod. I bought a switch from Radio Shack and mounted it below the dash. Best $4 I ever spent on that truck.

adrenalnjunky · Post by **adrenalnjunky** » Thu Mar 10, 2005 12:23 pm

Welcome to the site John!

aa21830 · Post by **aa21830** » Thu Mar 10, 2005 2:37 pm

Thanks, Chris. The folk s at ZR2.com mentioned this site, thought I'd see what was happening over here.

Pauleo · Post by **Pauleo** » Thu Mar 10, 2005 6:40 pm

Not sure about this TCC thing but I would definately like to do the transmission cooler mod. I read the info posted on it but I still don't get it. Anyone have better pics than the ones posted already? I really think it would be good to have when I'm pulling my utility trailer. That thing weighs about 1500 lbs EMPTY!

Also, never knew to keep it in 3rd!!!!

Glad I read THAT info!

Sorry guys. I just suck when it comes to auto mechanics. I don't know what the heck a core support or ANY of that stuff is. Can anyone help a brutha out???

Post by **HenryJ** » Fri May 27, 2005 5:49 pm

Pauleo wrote:... I don't know what the heck a core support or ANY of that stuff is. Can anyone help a brutha out???

Sorry that I missed this^

Core support refers to the panel , or piece of the body to which the radiator is attached. Core = radiator core.

Rusty wrote:
HenryJ wrote:...A shift kit might be another solution, as would the B&M shift improver and perhaps the TCC switch.

I forgot about the TCC mod. Did you ever have it set any codes or anything? ... How about the ABS since the purple wire seems to have something to do with that too?

I haven't set any codes, but Jim's research suggested the it would set a code with prolonged use. I have not used it for prolonged periods and haven't had any ABS lights either.
As before though, I just trip it when I need it on long grade, or in testing the converter lock.

I can't say that it is the best mod I have ever done, but I really do like having the control available to me.

Post by **HenryJ** » Sun Nov 27, 2005 4:35 pm

Well inadvertently I used this mod long term

It appears that I have had this switched , or unlocked since i did the 4th servo and longer pin. That may have been a month or so.

The shifts take longer to engage overdrive, and while cruising on overdrive the rpms are about 300 higher. I am sure it was not helping my mileage, but really the transmission seemed to be operating nicely for mostly city driving.

The reason I found out it was unlocked was that my cruise control was disabled

I switched it back on and the cruise worked again. I guess this means that it may not set a MIL with prolonged use. I really like the feel with the converter lock disabled.
The transmission temperatures do not seem to be affected.

Just some information on a test that I was subject to unknowingly

Post by **HenryJ** » Tue Sep 05, 2006 2:06 pm

I did a little playing with this on the trip this weekend last.

With the temperature gauge I was able to see what the temperature does with the converter unlocked.
I was surprised to see a little increase in temperature with the converter unlocked while pulling a grade. It does maintain rpm better and doesn't "search" for a gear. I did seem to run five to ten degrees hotter on a good grade while maintaining highway speeds.

On similar pulls with the converter locked, even though the engine was almost to the point of lugging the temperatures remained a little lower.

crew cab sonoma · Post by **crew cab sonoma** » Fri Sep 08, 2006 9:09 am

with the converter unlocked, its not surprising that temps climbed some. even mild converter slippage that occurs at highway speeds can generate considerable fluid heating in the converter.

kpietrowski · Post by **kpietrowski** » Sun Oct 13, 2013 4:10 pm

). I'd assume all the harnesses were assembled the same way. henryj unfortunatly this isnt tru haha i hoped it was but mine was the top purple wire.. mod works great good thread

Post by **HenryJ** » Mon Oct 14, 2013 3:47 pm

kpietrowski wrote:). I'd assume all the harnesses were assembled the same way. henryj unfortunatly this isnt tru haha i hoped it was but mine was the top purple wire.. mod works great good thread

Since they are both crimped into the same terminal, you have a 50/50 shot of getting it right no matter what you do. Sounds like you picked the right one the first time?

There is no way to say up or down, just the way I described it in my photo at the time , I guess.
Great to hear it is still working.

I often wonder if the new owners of my old truck ever figured out all the secrets

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