High-pitched squeal from power lock system

I just bought my daughter a '97 Rodeo. When the keyless entry button is pushed to lock or unlock the doors (which, by the way, doesn't work), a really loud, high-pitched squeal comes from the general vicinity of the firewall on the driver's side. I'm assuming the pneumatic system has a problem.

Anybody ever run across this?

Thanks,

DH

I just bought my daughter a '97 Rodeo. When the keyless entry button is pushed to lock or unlock the doors (which, by the way, doesn't work), a really loud, high-pitched squeal comes from the general vicinity of the firewall on the driver's side. I'm assuming the pneumatic system has a problem.

Anybody ever run across this?

Thanks,

DH
There is no pneumatic system for the power locks. They are electric.

Any idea what could be making such a horrendous sound? It's really quite piercing, and lasts for a good 5 seconds or more. I'm assuming the sound is related to the fact that the power locks don't work.

It might be a failed relay in what ever module is for the power locks for the 1997. I've seen relays make some strange noises when they go caput.
G/luck
Joel