Door locks auto lock and unlock when driving but not with MC switch or remote

RWCPRICE

MEMBER
2000 CHEVROLET SUBURBAN
5.3L
V8
4WD
AUTOMATIC
200,000 MILES

The door locks will auto lock when driving and unlock when parking. The door locks will not activate with the remote or with any of the lock switches inside vehicle (drivers, passenger, or cargo area). Able to manually engage the locks from inside and using key to unlock the front doors and cargo.

Fuses in dash have been replaced and the master control switch has been replaced.

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,747 POSTS

Hi and thanks for using 2CarPros.com.

First, I want you to try this to see if turning off the automatic lock/unlock changes things.
No doors lock/none of the doors unlock: Press the lock side of the power door lock switch on the door panel twice. This turns off the automatic door lock feature.

If that does not help or change anything, have you checked the door lock relay? Here is a link that shows how to check a relay:

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Finally, you may have a weak ground for the circuit. The ground is located on the left side/lower A pillar. That is basically where the driver's left foot would sit. I attached a schematic of the wiring to it. Picture 1 is a diagnostic flow chart of this type of problem. It requires a scanner to complete.

Let me know if you have questions or need anything. My first suspect is a bad ground or a broken wire into the driver's door. The wiring harness flexes and bends every time the door is opened and closed, so check an make sure everything is okay there.

Take care,
Joe

Images (Click to make bigger)