No TCC lockup...Transmission Range Pressure switch assembly?

My TC is not locking up on my 95 Z28. The tranny was rebuilt last year and a brand new Vig 2800 was installed at the same time. I'm in the process of getting a scanner to see what the PCM is doing. But in the mean time, what could cause the TC to not lockup?

The brake switch and VSS are working fine. There are NO SES codes, and the tranny shifts fine and normal (i.e. no harsh shifts from max line pressure, 2nd gear starts, etc). I'm inclined to think that it's not a solenoid problem otherwise I'd have tranny codes and/or the harsh shifts. Fluid level is perfect and is bright red, not burnt.

I did read something about a Transmission Range Pressure switch assembly...could that be it? I assume if the PCM is not seeing the correct tranny temp (too cold) then it will not lockup? Is this located on the valve body? Can you get this switch at the parts store or is it a dealer item? Even at normal operating temp, it still doesn't lockup. I've even replaced the CTS on the water pump just for giggles.

I'm hoping it's not the converter. Like I said this tranny works beautifully, it's just not locking up. Any ideas??? Thanks...

You may want to try this, If you have a voltmeter check the tan/w black stripe wire at the computer (blue plug) pin 11 . You should have 12 volts at this pin with ign on , when the correct speed is reached the computer or pcm
grounds pin 11 and causes the tcc solenoid to lock up.

You can pull pin 11 from the plug and ground it with ign on and hear the
solenoid click.

I just the other day ran a small wire connected to pin 11 and monitored
the voltage while running down the road . I had 12 volts at startup and
when the tcc lockup occured the voltage went to 0

Dave

Alright, I'm gonna try that. So if I don't hear the solenoid click, I assume the TCC solenoid is bad? Also by grounding pin 11, can I manually lock the TC that way?

Thanks for the tip. :cool:

Yep thats right, if you dont hear a click check for 12 volts on pin 11, if you
dont have it check your fuses, and if they are alright it could be an open
winding in the solenoid or an open wire.

And if you hear the click , you can manually lock the TCC by applying a
ground but you will have to use a switch so that it is not locked when
you stop.


Dave

Ok, I grounded pin 11 and sure enough I can hear the solenoid clicking. Just to eliminate the TC as the culprit, I grounded pin 11 while idling in "'drive" and it stalled out like its supposed to. I also grounded it while driving in 4th and it locks up just fine. So now I know the TC or TCC solenoid is not the problem, but...

While driving around with the TC locked in 4th, shouldn't it unlock if I step on the brakes? I tapped on the brakes while keeping a steady speed with the TC locked, and TC did not unlock. :confused: I'm gonna check the brake switch again and the wiring from it....

Thanks again for your help Dave!