Converter clutch (TCC) intermittently does not unlock

[Old Dave]

On two occasions in the last 900 miles, the TCC in my '92 Century 3300 with the 3-speed tranny had an episode where it failed to unlock when slowing to low speed or a stop. It actually stalled the engine before I managed to shift into Neutral at one point. Once I restarted, it was initially OK, but grabbed again before I got home. Manually downshifting to Low or Neutral seemed to help avoid a stallout on this latest instance, and once I got it to unlock, everthing seemed OK. Trans fluid is clean and full and most of the time, the trans works flawlessly. FSM diagnostic tree seems to indicate that the speed sensor or throttle position sensor could be responsible, but the MIL lamp is not lit and there are no stored codes. Since the FSM diagnostic process seems to rely exclusively on the Tech 1 diagnostic console (and since no one actually has these anymore), I'm not sure where to start - hate to just start throwing partsw at it. Anyone else experienced this problem or have any suggestions?

[CorvairGeek]

You could unplug the connection at the transaxle to disable the TCC and see if it is fine. The T125 (3T40) is well known for this problem.

[Old Dave]

You could unplug the connection at the transaxle to disable the TCC and see if it is fine. The T125 (3T40) is well known for this problem.

I thought about that, but my preference would be to solve the problem, if practicable. Running without the TCC would produce high cruising RPM, undoubtedly increase fuel consumption and maybe overheat the trans fluid, as the converter seems to have a fairly high stall speed.

[CorvairGeek]

Sounds like you already have a plan then.

[tlc1976]

Yes very common problem on the 3 speed. I?ve never had a 3 speed a body, but I did this job on a Corsica in 2003. Was about $30 and a half day job in my dirt driveway.

[Old Dave]

Thanks - but what did you find was the problem, and what was your fix?

[tlc1976]

The actual solenoid sticks. So you replace the solenoid. You access it by removing the side pan on the transmission. And replace the gasket when you reassemble it. On the Corsica I had to remove a mount and part of the subframe. I don?t know about an a body, but I would think there is more room to work.

[Psquare75]

My 93 Cavalier had a T125C. I replaced the solenoid twice over 10 years. Symptoms were as you described.. bucking and stalling at light when warm in gear. It will release when cool, then become stuck when activated again. Unplugging will bypass the solenoid. It's a simple plug to get at from the top of the car. Replacing is fairly simple through the side cover. No need to drain the transmission, but it will drip a bit.

[LG7rumble]

I've randomly had mine get "stuck" a handful of times over the 5 or 6 years I've owned the vehicle (3speed, got the car with 50k, at 85k now).

In every circumstance I am 100% confident it was some kind of electrical issue; I'd clean this thing or replace something completely unrelated (TPS for example), or just clean a couple connectors in the engine bay and boom, issue resolved for seemingly no reason.

That's not to say it isn't failing on you, but it's worth making sure electrical connections are clean and well-seated. Clean the junction above the firewall right under the far driver's-side corner of the hood (two cable harnesses with a hex bolt in the middle), clean the connection on your ICM, TPS, clean the connector for the solenoid itself. Clean some grounds while you're at it, there are two on the top portion of the radiator support and one on the bottom below the radiator; it also helps to unbolt the ICM bracket and hit it with a wire-wheel as well as where it mounts to the engine.

If you want to tackle replacing the solenoid yourself, this dude does it in a driveway: