GP1138 Posted April 5, 2007 Report Share Posted April 5, 2007 OK, here's the story. Roundabout the time of the 3400 topend swap on my GP, we replaced the thermostat with a 180* one that Autozone happened to have. I don't know when this problem began to occur, but my TCC does NOT engage. I don't know if it's possible, but could the 180* stat be causing my ECM to remain in open loop, thereby reducing gas mileage and causing the TCC not to engage? What set of conditions have to be met for the TCC to engage? Quote Link to comment Share on other sites More sharing options...
White93z34 Posted April 5, 2007 Report Share Posted April 5, 2007 heh, lets see. i *believe* that the TCC being engauged does not have anyhting with the car being in open loop. at least i'm 90% sure that my car will engage lockup while being cold. did you ever check the brake light/TCC switch i was telling you about, start there. Quote Link to comment Share on other sites More sharing options...
DiscoStudd Posted April 6, 2007 Report Share Posted April 6, 2007 One surefire way to check if it's in open loop without using a scan tool is to sniff your exhaust. The exhaust would reek of "richness" (too much fuel) if it were in open loop... Quote Link to comment Share on other sites More sharing options...
Robby1870 Posted April 6, 2007 Report Share Posted April 6, 2007 I had a similar problem.......turned out to be the coolant temp sensor on the LIM. It was literally disintegrated and thus was sending a "cold" signal to the ECM and the TCC would never lock up. Quote Link to comment Share on other sites More sharing options...
mfewtrail Posted April 6, 2007 Report Share Posted April 6, 2007 For lockup to occur, coolant temperature has to reach 130*F. Closed loop is also required for lockup. EDIT: I hit submit too soon. The 180 t-stat should not be a problem unless it's possibly stuck open. What does your temperature gauge on the cluster indicate? Do you have heat like normal in the cabin? FWIW, my TGP with a 160* t-stat hits closed loop easily even when the temps are in the 20*F range. I let the car idle a few minutes before driving it and it's up to temperature without an issue. Quote Link to comment Share on other sites More sharing options...
SigEpCutlass Posted April 9, 2007 Report Share Posted April 9, 2007 John...how are you so certain the TCC isn't engaging? Is it really that apparent...J/W... Quote Link to comment Share on other sites More sharing options...
GP1138 Posted April 9, 2007 Author Report Share Posted April 9, 2007 John...how are you so certain the TCC isn't engaging? Is it really that apparent...J/W... I'm not sure, maybe it's smoother on the E transmissions, but at cruising speed on the highway, I'll hit the brake enough to make the lights come on, and there will be no disengagement... also, Ken drove my car and he was saying that engine RPM's didn't correspond to the car's speed if lockup was occurring. Maybe it's all in my head. Quote Link to comment Share on other sites More sharing options...
White93z34 Posted April 9, 2007 Report Share Posted April 9, 2007 pull back on the brake pedel with your foot while driving and see if that makes a difference. Quote Link to comment Share on other sites More sharing options...
GP1138 Posted April 9, 2007 Author Report Share Posted April 9, 2007 pull back on the brake pedel with your foot while driving and see if that makes a difference. Actually tried that, didn't make any difference. I really need to investigate that switch, I'm really wondering if the shift cable is fucking with it. It's just been too fucking cold lately. Quote Link to comment Share on other sites More sharing options...
White93z34 Posted April 9, 2007 Report Share Posted April 9, 2007 ok, here is how i think you test the switch. on the white switch under the dash, there should be a purple wire, and a pink wire, get a test light and put it between them, with the brake pedal in the un-depressed position it should be lit, when you depress it, it should go out. Quote Link to comment Share on other sites More sharing options...
Crazy K Posted April 9, 2007 Report Share Posted April 9, 2007 ok, here is how i think you test the switch. on the white switch under the dash, there should be a purple wire, and a pink wire, get a test light and put it between them, with the brake pedal in the un-depressed position it should be lit, when you depress it, it should go out. I would think it was the other way around.... and would only happen at speed! Quote Link to comment Share on other sites More sharing options...
White93z34 Posted April 9, 2007 Report Share Posted April 9, 2007 how it works is when the pedel is at the normal non pressed position, current can flow through the switch allowing hte TCC to get power, when it is pressed the power is cut and it disengauges. it will work with the car parked. done it myself to test my switch. Quote Link to comment Share on other sites More sharing options...
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