power door lock problem on Tahoe

[rauto13]

I just bought a 2003 Tahoe and it has an intermittent problem with the power door locks. Sometimes when you unlock the doors, the rear doors or the rear hatch will not unlock, the front doors always unlock with the remote, when the rear doors do not unlock with the remote, they will not unlock with the inside switch either. Sometimes they work and sometimes they don't. Sometimes the rear doors unlock, but not the back hatch, the rear door locks are an inconvenience because I can reach around and unlock them by hand, but I can't open the back hatch at all when this happens.

I have tried both keychain remotes and they both do it intermittently, leading to me to belive that it is a not the remotes, but something on the vehicle. Maybe a bad switch? Or if it has a body control module, like some of the other late models, maybe that is bad?

Any input would be greatly appreciated.

[clinebarger]

Replace the Lock & Unlock Relays in the left I/P fuse box under the steering column(arrows).

The rear doors & lift gate locks are controlled by BCM through these relays, The front door locks are controlled by the door module.
Diagnosing BCM problems requires a Tech 2 scan tool, I would replace the relays first