Torque Converter lockup wiring question.

[Nodnarb76]

I'm in the middle of my LQ4/4L80E swap, and my instructions that come with my standalone harness states in needs 12 volts input from my brake pedal.
does this mean 12v when the pedal is pressed in or 12v when my foot is off the pedal?
I know older cars (including my 87 Suburban) are 12v when your foot is off the pedal and goes to no volts when the peal is pressed in.

[clinebarger]

Originally Posted by Nodnarb76

I know older cars (including my 87 Suburban) are 12v when your foot is off the pedal and goes to no volts when the peal is pressed in.

This is correct for all Gen III engines/PCM's.

[aknovaman]

It depends on which pcm you are using for early and late engines. Early ls1 style (24x) engines need 12 volts removed with brakes applued. Later e38 (58x) ecu need 12 volts applied with the brakes applied.

[Nodnarb76]

My motor/PCM is from a 2004. so I need zero volts when my foot is off the pedal, 12v when I'm pressing the brakes right?

[aknovaman]

Nope. Use a 4 pin gm switch from a 1990's s10. Two terminals for brake lights. Connect other terminal to switched ignition. Last terminal to purple tcc wire on pcm.

[ls1nova71]

Originally Posted by Nodnarb76

My motor/PCM is from a 2004. so I need zero volts when my foot is off the pedal, 12v when I'm pressing the brakes right?

Technically on an '04 you'll need both. Pin 33 (purple wire) on the C1 connector (blue one) will need 12v when the pedal is not depressed, and pin 6 (light blue wire) on the TAC module plug needs 12v when the pedal is depressed. Your truck should already have the right brake pedal switch with the two sets of connections on it unless it didn't have factory cruise control, which I would think would be odd on a fairly loaded suburban.

[Nodnarb76]

Originally Posted by aknovaman

Nope. Use a 4 pin gm switch from a 1990's s10. Two terminals for brake lights. Connect other terminal to switched ignition. Last terminal to purple tcc wire on pcm.

is this the switch you are talking about?
My existing brake switch has connectors for cruise control that I won't need, could I use those, or would you recommend getting one from an S-10?

[Nodnarb76]

For what it's worth, this is what mine currently has.

[ls1nova71]

Originally Posted by Nodnarb76

For what it's worth, this is what mine currently has.

That is the one you need. And just an FYI, since your truck has cruise already, it's only three more wires to hook up to make it work on the LQ4.....

[tinos555]

Originally Posted by ls1nova71

Technically on an '04 you'll need both. Pin 33 (purple wire) on the C1 connector (blue one) will need 12v when the pedal is not depressed, and pin 6 (light blue wire) on the TAC module plug needs 12v when the pedal is depressed. Your truck should already have the right brake pedal switch with the two sets of connections on it unless it didn't have factory cruise control, which I would think would be odd on a fairly loaded suburban.

Do you have to use pin 6 (light blue wire) even when not using cruise control?