Seem to be having an issue with the X2 harness to the bcm. Every once in awhile I lose the signal wire to the brake pedal position sensor. I have confirmed this with a multimeter by back probing at the sensor. I have ground and 5v reference but nothing when i push the brake pedal. Traced the wires back to the bcm (pin 31 yellow wire) and back probed it as well and reads zero.

With the meter still hooked up, I wiggle the harness around sometimes unclamping the harness and reclamping and then I'll get the signal back, confirmed by pressing brake pedal. It will work fine for a few weeks then all the sudden I get in the car and start it and first thing the traction light is on. Repeat the process of wiggling and unseating and reseating then it works. Happened again over the weekend except now it's getting more and more difficult to correct. I've cleaned, inspected and tried dielectric grease (can that make it worse?)

I labeled all the wires to their pin location on the harness and removed all the pins and used a needle nose pliers to squeeze the little slip on collars to make sure they are tight. Put it all back together but it didn't seem to help because if I play with the connector after it's seated I can still make the signal wire cut out. It's currently working right now but I'm preparing for the next bout.

What I want to know is if I get another harness at the junk yard and solder it in, will that cause any resistance problems for the bcm. I don't think I have to do all the wires, I would just do the three for the brake pedal sensor. I'm quite certain it's not the bcm. All the pins look good unless there's a loose connection inside the module. I don't have any other problems and surely i would think if the bcm was acting up there would be more wierd issues with the car.

 

I’m thinking your idea to get a harness connection from a yard , solder should not interfere on that one wire or the 3 wires.

 

The pin is probably loose either in the harness side or the BCM side. Loose pins can push out the back of the connector, and look fine when disconnected.

 

I got the harness this morning. It was identical match. I ended up soldering in the whole harness. There were other questionable pins on my old harness. Switched the wires one by one so there were no mix ups. Everything working great!

Tonight on way home from work, check engine light came on. Scanned it and getting code P0325. Definition on my scanner says knock/combustion vibration sensor 1 circuit bank 1 or single sensor. Never had this before.

Please tell me this doesn't have anything to do with the bcm. I looked at all the pin descriptions for X2 connector and don't see anything related to a knock sensor or even the ECM. Is there something else on that X2 harness that's related?

Could it just be the sensor? GM description for that code can be either high resistance or open.