Hi guys, I have an interesting problem/question. I have an 86 IROC TPI. The ESC module is located behind the relays on the firewall. HOWEVER, there is another "module" under the passenger side dash. This module is located towards the center console away from the ECM.

All the diagrams I have looked at list this as an "ESC module". Are there 2 parts to an ESC module? What is this module? It is a 4x5x1.5" black plastic box with a 12 wire harness going to it... Inside the box is a plain circuit board. No part numbers on the box, however, on the circuitboard itself has and AC and 25074637c. This number doesnt come up in the parts websites I have tried.

I am thinking it does have something to do with the ESC circuit, because last night during a race, the box fell out of it's bracket during a hard 1-2 shift, hitting the side of the console. The end result was performance fell off for a second or two and then came back in, the same way as if the ignition was being retarded and then back to normal. After the shift to 3rd, car responded normally and pulled all the way to the finish line. Subsequent races had no problems, but I just left the box hanging instead of messing with it. Now I want to know what it is, and why it affected performance the way that it did.

 

It is the cruise control module.

A hard shift can set off the knock circuitry with a subsequent retard. I've seen it with 700R4 downshifts.

RBob.