On the 91 Olds Custom Cruiser, on the drivers lock switch you can press unlock and all of the doors will lock. All of the doors will lock if you push lock.

If you operate the passenger side switch, all of the doors will lock if you push lock. But only the drivers door will lock if you press unlock.

Sometimes, the door locks begin to work 100% fine, but within seconds will chatter and go back to being strange.

I have the big shop manual, and tried to use the incomplete troubleshooting guide. This symptom was not listed as an option of failure, but I checked the A pillar lock relay and the recommended continuity checks and everything checks out fine. I looked at all the forums I could to solve this on my own, but I must ask. Any advice is greatly appreciated.

i dont have diagrams so this is a educated guess, but if the relay is the type that switches for lk and unlk then it could be stuck, otherwise possibly somthing in the driverswitch

I think I can check that in circuit. The book does provide the schematic of the relay. if anything is weird in there I should know. But in my experience, its never a relay. Looks like I'll have to sit down with a cuppa coffee and redraw the schematic so I understand it better.

relays wear out faster than switches, they have a bunch of moving parts in there and carbon builds on the contacts because it arcs every time it engages or disengages

Well, i marked up my book, and yes indeed, the relay can do that if the unlock positive to motor relay goes out. There are two relays in one box. I put in a new relay, and it acted the same way.

Next, i am going to test the door lock switches, as its easy to take those out. If that does not do anything, i believe this car had keyless entry. I am going to unplug it to see if the problem clears up.

It was the keyless entry module. Once unplugged, the locks began to behave normally. The drivers door did not lock or unlock as the drivers motor is controlled via the keyless module.

So, for any interested in deleting that function:

1. Leave both connectors to the Keyless entry module unplugged.

2. The first jumper point is on the larger of the two connectors going into the keyless module. It will be the tan wire.

3. The other jumper point will be in the connector leading into the tailgate. There is only one wire bundle. This will be a tan wire as well.

4. Jumper the two together securely, and you are done.

thanks for updating your fix