c-137

Hi. 85 T/A 305 tpi auto.. when driving, my torque converter clutch will lock up at low speed and low rpm.. like 1000 rpm at 30 mph in 2nd or 3rd gear. Does anyone have an idea what might be wrong with it? Shouldn't it only lock up like 45 mph or higher and only in higher gears? I believe the TV cable is adjusted correctly. Trans upshifts nice and firm.
thanks

72buickgs

Replace it. I do not know if the TCC is similar to that lockup on a 1995 Cavalier, but my daughter had the lockup that would work at low speed & then fail to unlock.
Replacement of the TCC

Tom 400 CFI

My '83 did that. It'd stay locked down to 900 RPM in OD. Never tried to diag it....never cared. If it affected the driving experience that I wanted, I'd just grab a lower gear w/the shift lever. Sold that car w/200k miles on the original trans. I don't think it hurt it at all. In fact, it may have helped it last.

Tuned Performance

iTrader: (92)

Is the speedometer correct ? This is HLL calibration

c-137

yes the speedometer is correct

c-137

idk HLL calibration.. how can i adjust the tcc numbers like you have there? Is that a special program that modifies the ecu?

Fast355

iTrader: (2)

That is Tunercat and you would need a EPROM programmer to program the chip.

Make sure the TCC wire is not grounding out somewhere. The TCC solenoid can also fail in an open state and allow the TCC to lock as soon as the transmission upshifts into 2nd gear. A functional test I perform, cruising at say 45-70 mph, if you give the brake pedal just enough pressure to turn on the brake lights, the engine rpm should increase 200-300 rpm. The TCC has a switch on the brake pedal that cuts the power to the solenoid when you step on the brakes.

You can also unplug the TCC harness on the driverside of the transmission as a test, if the lockup is still enabling the TCC solenoid has failed or fluid is somehow reaching the TCC apply passageways.

Tuned Performance

iTrader: (92)

HLL is a broadcast code you will have one on your prom. You can upgrade to a 27sf512 with a solder in adapter otherwise use a 2732a uv eraseable prom. Can edit in tuner pro or tc $1F

jmd

iTrader: (4)

Read some more threads here on TCC function and wiring.

A few things could cause or fix it. First, a bad solenoid may apply once warmed up and not unapply. If the vehicle is warmed up and you are driving steady and hold steady throttle, a momentary tap of the brakes should allow RPM to rise and then fall back down as lockup reapplies. If it doesn't do this, the solenoid needs replaced.

The ECM commands lockup once the vehicle is warmed up and thresholds of speed, and throttle are met. Those old threads you haven't read, or the factory service manual you don't/haven't read will get you more info on how to rig a test light, maybe from the ALDI port. Is it commanding lockup at 20some mph? It could be a part of the problem. Got a different PROM to try? You may have a tune that isn't a good match for your converter / gearing etc.

if you have the pan off, document the wiring and switches in the valvebody. Again, this forum has info on different stock or modded setups. There is at least one port in the 4th gear circuit, and commonly a pressure switch is installed, which can be a normally open, or normally closed style. If TCC is commanded, but the circuit cannot apply until in 4th gear, that is a way to prevent it, but it is less refined than factory setups. There are times when 3rd gear TCC is appropriate but 4th isn't needed or desired. As with a lot of troubleshooting, "how has this been modified or changed since 1985?" tends to lead to the problem and solutions.