91 SE: Power door lock problem

My 91 SE doors will unlock, but will not lock using either power door lock switch. Any suggestions as to the culprit would be greatly appreciated. Sure wish I had a Helm service manual or knew who has one for sale. Thanks.

I've seen them show up on EBay but it changes. On the lock function you may have lock and unlock relays so check that out. On your year model GP there should be a module maybe called a chime module that controls door lock/unlock functions. On newer GPs we have a body control module (BCM).

Also, try Autozone/Repair Info. They have some chassis wiring diagrams for your year and model.

The power lock relay is mounted under/behind the glovebox. Your car uses a reverse polarity system, and if any one of the switches is bad, it will cause the locks to either stop operating, or only work in one direction. I had a similar problem with my old winter beater 91 GP SE 4-door, and it ended up being the right rear door switch was shorted on one side.