I found out what this is! I was able to trace one of the wires into the front grill and saw a box.

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Which apparently is a very old radar detector.

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My new '84 Dodge B250 that I purchased through an auction has a mystery switch on the dash that I cannot figure out and I'm hoping to get some ideas before tearing into the dash. The switch is 3 position. It seems to be off when on the left. If I switch it to middle or right it beeps once. If I leave it there, occasionally/randomly it may beep a couple times but I believe only when the engine is running, not when in accessory mode. The little red led above the switch flashes when it beeps. It has 4 wires. Two of the wires head towards the fusebox in the glove compartment and the other two head into the dash towards the instrument cluster. I don't see any aftermarket boxes/devices anywhere on the vehicle that it might connect to. There is some additional wiring that appears to be audio related (a line-in setup I think) but it doesn't appear related. I would appreciate anyone who might have an idea what this could be for.

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Last edited by Grim; July 02nd 2018 9:47 pm.
1984 Dodge B250 Custom