case310350

Have an 07 uplander, I want to disable the toque converter lockup. In this forum there is a thread where a tan wire was cut at the transmission to disable the TC Lockup. Can anyone confirm that? Or have a way to trick the computer not to lock up. I know until the engine temp comes up there is no lockup. So could do that way. All advice welcome

oilcanhenry

Torque converter lockup is controlled by the TCC solenoid. When the solenoid is engaged, fluid is applied to the torque converter clutch, creating lockup and a direct link between the engine and transmission. This feature is controlled by the vehicle's computer. Pretty sure if you pull the wiring harness off the TCC solenoid, your T-C will not lock
up, but your tranny will generate more heat, and automatics and high heat mean bad things can happen. Might want to install an air/oil cooler on front of the radiator or A/C condenser.

tech2

what are you trying to fix by disabling the tcc?

case310350

TC is locking unlocking. Bad converter. Had tranny rebuilt 30k ago. All the shops I have talked to says they do not make a good converter for this van. Most TC have lock issue at some point sorta like CVT trannies good on paper but not in real world application. So want to defeat the converter lockup, then tranny will last. been many threads on over heat, not a concern for me. Tranny shop says it cant be done. Looking at all option, like trying to fool it, if engine does not come up to temp it won't lock up. but that leads to other issues.

KChevy75

I'm chasing the same problem now with my 2007 Suburban. I rebuilt the trans at 202,000 miles because of a broken forward sprag. Made the mistake of replacing the original torque converter with a reman. The reman TC has 90,000 miles on it now and shudders as the tcc pwm solenoid does it's thing. I spend a lot of money and time proving that it's the torque converter and not the engine or something else electrical. I proved it by performing what I've outlined below..

You can do it with a tuner but they are expensive or you can try the below first.

Disclaimer: If you do what I've outlined below, you are doing so at your own risk. My understand is that this is perfectly safe as it make the trans operate like when it actually had an on/off tcc solenoid like in older models so I felt safe in doing so myself.

What I did was I took the TCC PWM Solenoid and I notched on either side of the o-ring at the tip. Check youtube for videos of how to do this. What this does is turns the TC lockup circuit into an on/off switch like in the mid 90s and earlier vehicles with the same configuration. It locks up much more firmly.

I believe the uplander has a 4T65e transmission which has the same TCC PWM Solenoid and thus should operate the same was when modded.

After this mod, the transmission will have more of an abrupt lock and unlock. You will feel it unlike with the pwn solenoid which feathers in and out of lockup.

My thoughts about why these reman torque converters have this issue is the company that rebuilds them is using cheaper friction materials for the clutch. They are supposed to be woven carbon fiber per GM specifications. My research suggests that tc rebuilders didn't have access to the high quality woven carbon clutch material or didn't want to spend the money on it and used other solutions. I don't know if they are using the much cheaper paper clutches which were designed for the non pwm transmissions or something else but they don't last with pwm.

There'a s good youtube video where a transmission shop cuts a DACCO TC open and shows the problems with the clutch material. They did this because they had several dacco reman units go bad and were losing money. I read the other day that dacco is no longer providing reman torque converters. Not sure if that's correct or not.

tech2

is the issue a tcc shudder when it applies or releases? If yes, Is there a tcm flash update that addresses this concern?

case310350

thanks for that information. On an uplander its very hard to get to the solenoid, have to remove lot of stuff to get to the side cover.. so will try and do it electronically. have the wiring diagram and will cut wire to tcc. may have to put a fake solenoid in the circuit under the hood so computer thinks all is normal.

the TC fails due to clutch materiel is not adhering to the TQ. so now have high spots and shutter. in my case.

tech2

the tcm monitors voltage on the wire you will be cutting so putting a fake solenoid won't fool the tcm unless it has the same resistance and can actually pwm when its actuated. there might also be an issue of slip...when locked up the tcm expects to see no slip rate between the input and out put speed sensors. since you will never achieve lock up it might set other dtcs

case310350

I was going to buy tcc solenoid, same one in the trans. i did not account for the feedback of the input/output shaft speeds. I see there is a temp sensor for the tranny. I know there is no lockup until something comes up to temp. now is it the tranny oil or engine? Now considering faking it via temp sensor. if its the engine then that could prove to be inefficient way to do it as it will run rich.

Would you know which one? also any suggestions? I was told once the brakes are applied lock disengages, but that does not happen. Going to wire a light to the adld so I can see when it locks/unlocks

tech2

if you have a 3.9 vin 1 build...the tcm is external to the transmission...you could wire up what ever you want. I have no idea what the outcome will be. Shops don't jimmie rig stuff; if it fails...you get sued.