My central door lock system has gone haywire on my '83 wagon.It makes noises when I turn corners, automatically locks when I close the driver side door. I'm hearing popping sounds coming from behind the dash intermittently. Could it be a bad relay? If so, where is the relay location and part number? Thinking I'll make a trip to the junkyard. Thanks ahead for any insight ~ Jim

The lock/unlock relays are very unlikely to be fail. You can disable the central locking system by unplugging a connector. That will stop your intermittent self-locking problem while you trace down the fault. The connector is above the driver's left knee, so you remove the felt/cardboard panel there and locate a three-wire white plastic connector. The wires going in-out will be Red, Green, and Black.

As others have said, the issue is probably in the system leading to the relays, and the most likely area is the door wiring or the switches. (Key and knob). You will have to pull the door panel and start inspecting in there. Another possibility is that the wires in the rubber bellows at the door hinge have lost their insulation and are touching each other. That's a place to look after the other mentioned places check OK.
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Bob: Son's XC70, my 83 240, 89 745 (V8) and XC60. Also '77 MGB and some old motorcycles

To answer your question directly there are a pair of relays dead center of the center console clipped behind part of the dash sheet metal.

I would look at the switch in the driver door first. Sounds like it is signaling the relays to operate and has a history of failure.

I second this post on it being a door key switch or at least the wire connecting to it.

I have seen into a few drivers doors at junkyards that were missing their panels. Their wiries in that area were pitifully bare of insulation!

The relays are probably responding to that gremlin inside!
Phil