Why Change Your TCC Solenoid?

Your car always stalls when you slow down to come off a freeway and the speed gets below, say 25 or 30 mph. You've eliminated an engine problem as the cause and you've read through my features on how to Diagnose Automatic Transmission Problems and Diagnosing GM Converter Lock-Up Problems. You know you have a bad TCC solenoid and you think you're in for a big bill at the dealer or transmission shop to have it replaced. Well, if you are a moderate to advanced DIY, this is something you can do yourself. It does involve opening the transmission and working with the valve body, but it can be done successfully with some care and patience. Note that these instructions are for the GM 3T40 automatic transaxle. If you have the 4T40 automatic transaxle the procedure is more complicated and should be left to a professional.

To do this job, you will need the GM J 28467-A Engine Support Fixture which you can rent at your local tool rental store. If you cannot find one, you can make do with a fence post attached to the strut towers and a chain attached to the engine support. Don't even consider using a 2x4. If you do have to use wood, I'd be scared of using anything less than a 4x4. If you do it this way make very sure it will not move or shift while you are working. Jacking up and supporting the engine from underneath is a good way around the fixture. But if the fixture is available, I strongly recommend you use it.

Before starting the disassembly procedures, I would suggest cleaning the engine and transmission with an engine degreaser. A clean transmission is easier to work on and helps prevent dirt or contamination from entering the transmission during disassembly and assembly.

I'm going to break this down into three segments to make the instructions a little clearer. Okay, with that said let's get dirty!