marker lights/tail lights relay

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Sep 11, 2012
Rossland, B.C.
Fun problem with my truck tonight. 1990 22re pickup. Arrived back from an 8 hour drive. Dash, side marker, and tail lights won't turn off. Slamming the door helped, but only somewhat. Bashing on the dash also helped, but with some buzzing and a bit of time, lights all came back on. Buzzing came from a relay near the main fuse block in the driver's side kick panel. Round silver thing, part number 90987-01003 on it (Toyota part number) from Denso. I pulled it out and the lights went out, which is good. Do the relays fail with these symptoms or is it a loose ground or a short somewhere else? I don't mind replacing the relay if need be, because it is probably 32 years old.
So the relay is not likely the problem? Which switch might be the culprit? Ignition? I will be looking at the wiring diagram in the FSM. Pouring rain right now so I'm not keen to get out there.
Its one of three things
Relay is bad or connection is corroded. (relay possibly has water intrusion)
Headlight switch.
A short to ground between the relay and switch.
It's a pretty simple circuit
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It stopped raining for a bit so I went out for a look. Plugged the relay back in. Lights stay off, at least so far. There definitely could be moisture as the whole truck is damp from driving in pouring rain. I tested tail, brake and signal lights. I think the headlights are on a different relay, something to do with daytime running lights. I forgot to try light switch on the stalk for tail and marker lights. Headlights do turn off, which is good. I don't want a dead starting battery. I will keep digging in the next little while.

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