Anyone know where this is located on a 99 and silverado 1/2 ton? I just got a code 0740. And the converter will sometimes lock up and sometimes not, so I think it is the switch.

 

Torque Converter lock-up is controlled by the PCM.
Not sure what the code is but someone will come along soon to help!

 

there should be a wire that goes the the brake wires. when hte pedal is pushed it unlocks when its not touched it locks up.

i had to wire this switch in when we did the PINKS race car. its just 12v to the switch and then the signal wire to the ECU

 

thanks quik, I'll mess with it some more tonight. Seems to have a mind of its own like the AC, sometimes it works sometimes no---def. electrical.