I have a '93 Toyota Pickup with an electrical issue. The switch to turn on the headlights doesn't work correctly. The switch turns on the headlights just fine, but does not turn on the rear running lights or the dash lights, and the standard "key out of the ignition with headlights left on" noise does not come on. The bulbs are fine. When I tested the rear with a voltmeter, no voltage is getting to bulb when the lights are on. A relay that turns on when the switch is applied is working fine (I could only find one relay). So, something is messed up. Anyone know what other things I could look for? Thanks.

Try these pdfs, they are the wire diagrams for the head and tailights
The tailight/dashlights have their own fuse and relay.
I would also suspect if equipped , the trailer wire converter box.

I am having a similar problem but with the front parking lights and the lights on chime. I suspect the integration relay.

Will try one next time I am by the dealer. One little relay should not cost too much.

I'll let you know when I have tried it.

Yes, sounds like relay issues. Typically, Toyota electrical systems are flawless. When something usually crops up, it is normally a relay, or where someone has tampered with the original electrical system for add-ons, etc.

where someone has tampered with the original electrical system for add-ons, etc.
You got that right :D , you should see some of the stuff people do.:eek:

There are two relay's. The one inside on the fuse box is for the parking lights.