woodi

I've been working on wiring some plow lights for my 94 toyota pickup. I put a switch in the dash that toggles between normal operation or plow lights. When you hit the plow light switch it sends power to a relay which in turn powers either the high or low beams based on the state of the relay. I connected the ground from the relay to the r-y wire that should be off when the low beams are on giving me low beams in the relay's normal state and high beams when the high beam switch is on. What's happening though is that the combo switch apparently doesn't seem to work properly. In either state the relay is grounded and clicks on the high beams.

I tested with a test light and if I connect to the r-y wire when the low beams are on touching the battery terminal I get a real weak light. If I touch with the high beams on I get a nice bright light like you would expect. Is this something that could be caused by a worn out combo switch? Any other ideas? This is driving me crazy.



Oh and I did test to make sure the relay works right, I disconnected the ground wire form the relay and the low beams worked, touched the neg terminal on the battery with it and the high beams clicked on.

woodi

I took the combination switch apart tonight and it appears to be working perfectly. I tested the outputs from it and it switches the ground completely so now I'm really at a loss. In the process I somehow went from a weak ground on the high beam wire to a strong one. But here's the real baffling part. Lights still work fine high/low switching when I have my toggle switch in truck light mode but no matter which position it is in i still have a ground on the high beam wire.

desertcamper67

I've replaced one with one from the junk yard. Never repaired one though.

woodi

I eventually figure out something that works. I dunno what causes it but apparently there's some strange magic that goes on within my truck that even if they're not switched on all the headlight wires are grounded at the back of the lights. I think it might be back feeding through the headlights.. But I ended up using a dpdt switch for my plow lights and switched the power with one and the high beam ground right behind the steering wheel with the other one. It all works perfectly now. Only took 10 hours to get them working...