OBD1 LT1 4L60E TCC lockup (lack thereof!)

Happy new year everyone! I need some brain help here.

I've owned my '95 Chevy Caprice 9C1 (police package) for 10+ years and 50k miles and it has NEVER locked the TCC on its own since the day I bought it. I've had three different transmissions in it, two different torque converters, three different PCMs, multiple tunes, and nothing. Trans has a TransGo HD2 shift kit in it which overrode the TCC PWM solenoid, so it's just on/off based on the TCC enable solenoid like a '94 B-car is setup (although the apply/release tables are still setup like a '95). I eventually wired in a switch that grounds the TCC solenoid and I've just manually locked it once I get up to cruise speed. The transmission will lock the converter no problem, every time I throw the switch. The transmission is a '95 with the correct harness and solenoids in place and hooked up. There were no DTCs present during the attached log.

According to the GM B-car Factory Service Manual (FSM), page 7A-8, the following components play a role in TCC operation:

• Cruise Control Release Switch (this car never had cruise control but I added it later, no change in TCC behavior).
• PCM
• TPS
• MAP sensor
• VSS
• ECT

Through Datamaster I have verified that all of these sensors and switches are working properly. I'm posting the tune and log I took this morning after a battery-disconnected PCM reset with the TCC override switch deactivated.

I took a look at the tables in the tune and the only thing I can think of now is that unless I've missed an ECM switch or constant, maybe the PCM is somehow running in Performance mode, which never locks the converter?

Glad to see you made it over here sherlock9c1! :happy:

Hope someone can help as I'm not the tranny guy your looking for. But can give a tip on how to find an issue with bin. Pretty sure TunerCat does this as well but I use TunerPro mostly. Upload your bin and a known stock bin and use the Compare feature! You can look at every parameter and see if there is a change.

HTH!

If you care to try the TunerPro data logging it can also do all tranny data as well as all engine data with a change in "Connection"... way more stuff then data master.

Hi again Mark! The problem is not in the transmission - it's in the PCM. The PCM is simply not commanding lockup. Stock tune, aftermarket tune, no change. I'm going to put a stock tune in it again this weekend (it's been 8 years since the car's had a stock tune) and see if it makes any difference.

Pretty sure the TunerPro .adx file data log set to transmission mode will show the lockup as well... if that helps? Use the"Compare" feature!

Weren't you here before? Do you have 2 accounts now? I can combine them if you could not get in and signed up again?

Nope, same account, but I figured I'd "reintroduce" myself so if anyone else was in North Alabama, they'd be able to search and find me.

I'll try the TunerPro transmission logging.