cbence

I would like any help I can get on a preplexing problem. First, after turning on my headlights, then turning them completely off, the headlights go off, but my front parking lights, tail lights and instrument lights stay on. After I removed my battery cable, of course they went off. I reconnected the battery cable and they lights stayed off.

I turned the lights off, then on and removed the light switch completely and the lights still stayed on. I hooked up my test lamp and there was power to the parking light-tail light circuit. I disconnected the battery cable and the lights went off.

I then straight wired the parking light-tail light circuit to the hot wire in the socket (with switch removed) and the lights came on. I broke the circuit and the lights stayed on.

Anyone have any idea how there is power to the circuit with the switch removed?? The wiring diagram shows the hot wire running from the light to the light switch, but it appears the circuit is getting power from another source.

Thanks,

Chuck

Aussiblue

Sticking headlight relay contacts (the power for the lights goes through the relay not the switch - the switch triggers the relay). You most likley need to clean the contacts (it the relay can be opended) or replace the relay but 1st check and clean the plug on the relay with contact cleaner lubricant.

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Regards Blue

Fat F100

I'm with aussieblue on this. Replace your headlight relays. You might even have better lighting with new ones.

cbence

Thanks Aussieblue and Fat F100.

You have reinforced my thoughts. I found a wiring diagram in my Haynes manual that showed the wire going to the Tow/Marker relay. The three relay sockets on 1991 F150 are all different, so I could not substitute one of the good relays to check it. I took the relay out and am getting a new one today. I will post my results.

Thanks again,

Chuck

cbence

Thought I would let you folks know that I solved the problem by replacing the relay.

Thanks,

Chuck