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Transmission Control Module

09-11-2006, 08:00 AM
I have a 2001 Buick LaSabre and need to replace the Transmission Control Module. Where is this located on the car and is it difficult to replace.

Thanks for any help.

09-11-2006, 10:53 AM
Welcome to AF.

It might help to clarify what you are looking for. The tranny is an electronic transmission so it has electrical solenoids which are controlled by a Powertrain Control Module aka PCM module.

What problem are you having?

09-11-2006, 11:54 AM
The code recieved is "P0742 Torque Converter Circuit Stuck On" After the car warms up and when stopping and starting there is a jerking motion when it is shifting. Once up to higher speeds it works fine.
Thanks for the help

09-11-2006, 12:47 PM
That is certainly not good news. It is a valid DTC error code for a 4T65E tranny. The P0742 DTC means the torque convertor clutch (TCC) is stuck on indicating you have a valve body related problem. Possibly the TCC-PWM solenoid and/or wiring at the 20 way electrical connector. This DTC is a type A fault code and stored in PCM memory for retieval. It will disable shift adapts and commands the TCC on at maximum capacity. Symptoms are shaking, jerking and a bogging effect.

The TCC-PWM solenoid is located under the tranny side cover (driver's side) and not technically a DIY job so you may need professional help.

How many miles are on your LeSabre and when was the last time the tranny was serviced for ATF and screen filter?

BTW - Also, the PCM module could cause the problem but it is typically tranny related.

09-11-2006, 01:29 PM
The car has 144,000 miles. At 100,000 miles the ATF and Screen was suppose to have been changed. There was other services to be completed on the car at the same time. I discovered later that were not done. It is possible the Transmission was also not serviced. I will go and do this today. Could this cause the problem?


09-11-2006, 01:55 PM
It would be nice to confirm whether you had the service at 100K miles on the tranny. Have you inspected the condition of the ATF and level? One word of caution is do not get a full power flush or fluid exchange flush with your mileage because it could cause more problems. Hard to say that is the problem but it is a good starting point since the tranny repair (solenoid only) could run around $500 - $800.

Also, a lot of us have tried adding trannny additive such as Lubegard, Lucas or Seafoam. It may help free up the sticky solenoid but no guarantee it will work. Good luck.

09-11-2006, 05:32 PM
Had the tranny checked and sure enough the 100K service was not performed. It was paid for but I guess the shop it was taken to decided it was easier money to not do it, but charge for it anyway. Had the serviced completed today and watched as they did it. Drove it for 120 Miles and seems to work great. Appreciate the help. Talked with two transmission shops local and both told me they would need to take the tranny apart to see what the problem was. Glad I didn't do that.

Many Thanks,
James Weeks

09-11-2006, 07:58 PM
Watching these posts I was a bit confused how the TCC would engage and hold. Usually its the opposite. The TCC control comes from the PCM and if disconnected it would release in a normal transmission. I have had Famous trannie shops recommend rebuilt trannies and found before the work was done a simple grounding wire loose. Nice to hear your success.

Welcome to the fourm.

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