Power locks not working properly

JESSE SEAVER

MEMBER
1996 CHEVROLET TAHOE
5.7L
V8
4WD
AUTOMATIC
190,000 MILES

Having a problem with power door locks. The vehicle has an aftermarket alarm keyless entry system. All doors lock with control and both door switches but only drivers door unlocks with remote or either door switch. Passenger doors and rear door will not unlock by switch or remote only manually. There is no noise of actuator engaging for unlock option on any of the doors only when locking them does it engage. Also power windows are only accessible through drivers door control switches with or without window lock engaged. What should I check?

Saturday, May 1st, 2021 AT 6:42 PM

1 Reply

JACOBANDNICKOLAS

MECHANIC
110,119 POSTS

Hi,

The first thing I need you to check is the power lock relay. We know it isn't a fuse simply because some work.

The relay is under the instrument panel. If you look at the first pic below, it shows the location. Pics 2 and 3 show the wiring schematic for the door lock system.

What I need you to do is remove the relay and inspect the connectors. Make sure they are clean and tight. Also, make sure there is no rust or corrosion.

If needed, here is a link that explains how to test a relay:

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

Note: I cut the schematic in half so it is more readable for you. I did overlap them so you can follow from one to the next easier.

Let me know what you find or if you have other questions.

Take care,

Joe
See pics below.

Images (Click to make bigger)