Is there an electrical connection between the brake switch and the 4L60E? I just stumbled over a note on a 4L60E installation instruction from a engine/tranny supplier called Salee and they show a schematic for a harness required that cuts power to the transmission when the brake pedal is pushed. Anyone heard of this before?

 

hmm... not for the transmission.. but for the cruise control. There is a brake switch circuit for that.

 

The torque converter clutch is locked and unlocked based on whether the brake switch is applied or not (one of many variables). On earlier cars it went directly to the transmission. Now it is an input to the PCM, and then the PCM unlocks the TCC.
Even though it goes to the PCM, it is still considered part of the transmission wiring.
If you don't hook this wire up; no TCC operation.

 

John... I've been looking into this. I never hooked up my brake switch but my TCC still locks up.

I'm rewiring the car again and will hook it up now... but just an FYI... perhaps over a period of time that it sees the circuit open, it just ignores it?

 

Dana at LT1 wiring said it actually puts the trans, into a free wheeling mode, didn't really make sense to me because i thought it just would unlock the the converter. I used a brake light switch from a monte carlo that had cruise control so when i draw brakes it grounds the circuit. When pulling a hill and you tap the brake without letting off the gas the converter unlocks for a couple of seconds because the rpm's goes up about 150 and then relocks and the rpm drops back down. When going down a grade say 70mph and you have to draw brakes to hold that speed the trans. actually does go into a freewheel mode i guess because the rpm's drop 400 to 500 rpm's and you can tell the engine quits holding back. Take your foot off the brake and in about a long second the thing reengages and the rpm's come back up and the engine goes back to holding back. Does exactly the way i understood him trying to explain it to me, a dummy on this electrical stuff.

 

Must have stumped everyone. I have never driven a new LS1/4L60E to see if this is the way it works on new vehicles. Mine is the only ls1 i have ever driven.