1995 K1500 LS Swap TCC Unlock Sense

[Gnasty1521]

I have swapped in a 2005 LQ4/4L80E and I am having some issues with the TCC dragging I think. The truck cuts off in R and D at a stop, and driving up to temperature, I can smell ATF (which I believe is cause of the TCC getting hot).

I used a standalone harness from Current Performance, and they have the few wires to splice into the original to make everything work as it should.

I am trying to perform troubleshooting, as I had the transmission rebuilt, and a shift kit installed with a new Torque Converter due to the old transmission having milky fluid from sitting out at the junkyard, but showing the same symptoms as this newly rebuilt one. I unhooked the electrical connector, and it does the same.

I have not hooked up the brake sense wire for the TCC lockup (purple) because I haven't located the wire in/around the brake switch which gives 12+VDC and 0VDC when the brake is pressed. Does anyone know if there is such a wire in the 1995? I am thinking there should be as the original setup was a 5.7/4L60E.

This hookup to work the TCC Solenoid is my fist step before I buy the Sonnax Pressure Regulator valve for the 4L80E.

 

[Schurkey]

I have swapped in a 2005 LQ4/4L80E and I am having some issues with the TCC dragging I think. The truck cuts off in R and D at a stop,

You're saying the TCC engages in reverse?

 

[Gnasty1521]

No, it just drags enough to cut off the engine in gear at a stop.

I never hooked up the tcc wire, but I'm wondering where to hook it up so I don't burn up a torque converter when I find the mechanical problem.

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[Schurkey]

First Guess: Defective torque converter.

 

[Gnasty1521]

The previous torque converter, and this brand new one do the same exact thing. Doubt it would be that coincidental.

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[Gnasty1521]

My transmission builder has gone through this with me and he didn't replace any hard parts. We did replace the converter.

I'm just trying to find out which wire is the brake signal wire that's 12+ constant, but 0 with the brakes pressed.

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[L31MaxExpress]

My transmission builder has gone through this with me and he didn't replace any hard parts. We did replace the converter.

I'm just trying to find out which wire is the brake signal wire that's 12+ constant, but 0 with the brakes pressed.

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It exists in TBI engines that used the 4L60E or 4L80E. I believe it was a white wire pinned into E10 on the TBI PCM.

 

[Gnasty1521]

It exists in TBI engines that used the 4L60E or 4L80E. I believe it was a white wire pinned into E10 on the TBI PCM.

So, I would have to plug the pcm back in to get that signal?

I'm not running it currently, so maybe the relay is easier? What is everyone else running?

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[L31MaxExpress]

So, I would have to plug the pcm back in to get that signal?

I'm not running it currently, so maybe the relay is easier? What is everyone else running?

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It would be best if the PCM knew when your foot is on the brake.

 

[Jglew82]

I used a relay on my 90 with a 6.0/4L65E.

Relay pin 30 to key hot source,
87A (NOT 87) to PCM C1 pin 33 TCC,
85 to ground,
86 to the brake light signal from the brake switch.

This will give your PCM the TCC signal when the brake is released and remove the signal when the brakes are depressed.

*edited for formatting