Relay ?

[drakon543]

ok so the relay controls the second unlock signal that goes to the rest of the doors

 

[drakon543]

so i cant find a diagram but based off what the truck is supposed to do. its still functioning correctly with the relay in correctly just being annoying? so there is a loop somewhere between the brake switch the shifter electronics and the door unlock function. the brake pedal is depressed to place the vehicle in park. so there's a signal that goes to the electronic shift lock. placed in park and then a signal is sent through that relay and automatically unlocks the doors. without something failing yet the best i can suggest without throwing parts at a problem is check the wiring in your steering column for frays or any obvious damaged wires. you could have a bad wire that has an intermittent ground problem thats causing it to trigger that relay. however without the second signal to actually trigger the locks all its doing is flagging that relay.

 

[iamdub]

You can program your locks to do various functions based on the key position, if its in gear or park, if the vehicle is moving above a certain speed (15 MPH?), all doors or driver or only to unlock when shifted to park, etc. I wonder if the relay is ok but something that tells it to do whatever is faulty. I'm betting yours are programmed to lock at 15 MPH, not sure about your unlocking settings. Due to how common it is to fail, I'd suspect a faulty circuit in the brake switch.

 

[drakon543]

so i did find what should be the correct wiring diagrams but there is multiple different diagrams and the one thats listed as "luxury" i still cant find. none of the diagrams i found show any relation to going into park and unlocking the doors. so maybe your bcm is starting to act up. im still not really sure.

 

[rockola1971]

so i did find what should be the correct wiring diagrams but there is multiple different diagrams and the one thats listed as "luxury" i still cant find. none of the diagrams i found show any relation to going into park and unlocking the doors. so maybe your bcm is starting to act up. im still not really sure.

The programming is done via the drive. The options are listed in the message display on the instrument cluster. The mode and set function is controlled by buttons on steering wheel. If the mode is set. The locks will unlock automatically when vehicle put in park. You wont find this feature in the schematics. Its internal programming within the BCM. You should find the BCM giving that relay a ground (doesnt matter at this point as to when). The ground wire to that coil of the relay sounds like it rubbing against chassis ground intermittently which will cause this symptom. Unfortunately an erratic BCM with internal problems will cause the symptom also. Id find a BCM that matches body trim and part number and see if it clears it up if one can be found relatively cheap.

 

[drakon543]

The programming is done via the drive. The options are listed in the message display on the instrument cluster. The mode and set function is controlled by buttons on steering wheel. If the mode is set. The locks will unlock automatically when vehicle put in park. You wont find this feature in the schematics. Its internal programming within the BCM. You should find the BCM giving that relay a ground (doesnt matter at this point as to when). The ground wire to that coil of the relay sounds like it rubbing against chassis ground intermittently which will cause this symptom. Unfortunately an erratic BCM with internal problems will cause the symptom also. Id find a BCM that matches body trim and part number and see if it clears it up if one can be found relatively cheap.

ya thats the part that gets me os that its not shown anywhere. im painfully aware of gms nonsense through doing my various upgrades and repairs to various vehicles. there should be something shown on a diagram somewhere. i can see the wiring from the main switches to the rest of the doors. but i haven't seen a single one that even shows its connected to the bcm even tho i know it is.