Good evening. I have a 1998 Chevy 3500HD quad cab. Been having issues for a while with the power door locks randomly locking or unlocking on their own. Sometimes a dozen or more times in a minute or so timeframe. Might not do it for hours, then might start and continue for hours. I've replaced the driver side switch and still happens. Checked the wiring in the doors and it appears fine. Unfortunately the fuse panel access doesn't have any labeling for what fuse is what, so I haven't messed around in there yet I haven't spent much time yet troubleshooting, will be doing that tomorrow I hope. Anyone have advice on what to look for besides a shorted wire or faulty switch? Thanks.

I would look for corrosion on the connections to the door locks from the cab and also on the ECM module connector.

Check each individual door lock actuator you have one going bad

bad key fob ?????

I bought a used Buick in the mid to late 90's and had the same issues along with the instrument cluster flashing on and off as well. After much investigation we discovered the car was actually completely submerged in a flood. For some reason that information wasn't passed along to me at the car lot.

I have CRS but I do have the factory manual for that truck with wiring diagrams. I think there is a separate module for the remote locks which might be the problem. It doesn't have any aftermarket alarms or remote start does it?

The passlock module might could be a issue . Check a wiring schematic and see it the doorlocks are routed thru it .