Need trouble shooters: TCC lock and unlock in 3rd

[nuc]

TCC locks and unlocks back and forth constantly while in 3rd at ~32-35 mph. when cruising with no acceleration. Only does this when the car is at operating temp. (not cold). In 4th and at highway speeds the tcc functions normally. I have correctly adjusted the TV cable and brake switch, replaced both pressure switches, the tcc solenoid, changed out the ecm and changed out the chip, all to no avail.

What's next?

If the TCC wire was grounding out, wouldn't the switch be activating even when the car was cold?

Thanks

Adam

 

[are_one]

I have this exact condition. When I posted a few months back, I was just told to not drive in that speed.

 

[QuickWrench]

This is most likely due to the programming of the chip you're using. You didn't specify whose you're running, but I'd guess that your chip observes the factory's TCC lockup schema, which is to lockup at 35MPH in 3rd gear [under part-throttle conditions]. The reason you're not having this "problem" in 4th gear is because the car is already going faster than 35 at that point...therefore it won't unlock.

Most savvy chip designers raise this number to around 45MPH to get rid of this annoying habit.

 

[nuc]

When I bought the car several years ago with stock chip and injectors it did not do this, changed to a modified ecm, max effort and 55 pounders, it did not do this. All of a sudden, 2 months ago after using the max effort and 55 pounders for over a year with no problem, it started to happen.

Bought one of turbotweaks chips to see if the chip was causing the prob., but no, problem is still there.

TCC never engaged in 3rd until 2 months ago, with nothing having been changed within the past year. So there must be something wrong.

It is engaging and disengaging on its own, there must be something making this happen when it shouldn't be.

Other ideas???

Thanks

Adam

 

[petesgn]

My car was doing this also turned out to be a bad TCC solenoid.

 

[QuickWrench]

Given all the new info...I'd definitely lean toward the TCC solenoid.

 

[nuc]

As in the first post, I have already replaced the TCC solenoid with a new one.

This is a confusing hairpuller!!??!!

Keep the ideas coming

Adam

 

[QuickWrench]

Do you have a manual TCC lockup switch wired? If so, lock it up from a dead stop. It will lock the TCC as soon as you hit 2nd gear. Accelerate slowly up to around 55. If the TCC still does the unlock/lock boogie, it's the solenoid, wiring, or something associated.

 

[nuc]

Thanks for the idea, I will do it and post back.

Adam

 

[nuc]

Ok, I locked up the TCC using the ALDL and the locking and unlocking didn't happen anymore. Obviously the TCC was locked in 2-4th gear but it stayed locked and did not turn on and off.

What do I need to look for next?

Thanks

Adam

 

[Topjimmy]

Possibly the TCC unlock switch is out of adjustment at the brake pedal...if the car has cruise control, does it work?

HTH - Jimmy

 

[Dave Levey]

You need to put a scan tool on the car and observe your VSS signal, look for it to be eratic (mph jumping up and down), my guess is your bouncing above and below the point where tcc is comanded.By manually locking the convertor and having no problems you confirmed the wiring and machanical parts are working properly.Oops I forgot about the preesue switches that tell the ecm what gear you are in also check those outputs on the scan tool fo eratic readings.

 

[nuc]

The brake pedal switch is adjusted, the pressure switchs have been replaced as per the first post. I will put turbolink on today and see if the mph readings are erratic.

Thanks for the idea. I will post what I find out.

Adam

 

[nuc]

WELLLLLLLLL,

I hooked up turbolink and the speed is shown to be changing all over the place. 23,46,67,25,37,42,12, etc...

This is all at an actual speed of ~ 15 mph.

So, I guess we may have found the problem. I need to replace the VSS, right?

Thanks

Adam

 

[nuc]

ttt

 

[nuc]

And the solution was.......the VSS was bad. Replaced it with one from autozone and everything is perfect.