I can't turn my parking lights and marker lights off. I disconnected the battery. I reattached the battery cable and the lights did not come on. I turned the lights on and then turned the switch off but the lights did not go off.

My guess is that a relay could be bad. I had a body guy weld in new front cab mounts. When I picked it up today he told me he had a small fire. He melted the heater box. He replaced it with one from a junk yard. Does the wire harness for the marker lights and parking lights and tail lights run in the area? And what would make the lights stay on? The lights are not on all the time, only after I turn the lights on and then turn the switch off.

This is on my 70 F350.


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I would be leaning toward the headlight switch. While a relay can stick, there should not be one in the headlight circuit unless added by a previous owner. Double check the area of the fire for damaged wiring in case something was missed.

 

X2

After turning the lights off, disconnect the wires from the switch and see if the lights go out.

Welding (mig/tig style) needs to be done with the battery disconnected.

 

Update: today I looked at the wires under the dash above the heater box. They looked OK. I didn't see any melted insulation on any wires. So I connect the battery and the lights did not come on. I turned the lights switch on and the lights came on. I turned the switch off and they went off. Tonight after mowing at the our soccer fields, I turned on the lights and they came on. When I turned the light switch off the lights went off as they should but I noticed the instrument panel lights and heater control light were on. I thought, "Uh-oh". I got a hot wire...." The dash light went out when I turned the ignitition off.

So maybe it is my light switch. Interestingly, the dash lights and heater control lights were brighter than ever before since I have owned it for 2 years. I think my rheostat is bad but now I can not dim the dash lights by turning the ****, so perhaps there is a short in the switch.....

Thoughts and advice, please.

 

Oh, another interesting electrical situation. Before the fire my right turn indicator did not work. Last summer I took out the instrument panel to take a look. I replaced the bulb, but it did not light. I am not an expert but it looked like there was a break in the printed circuit board. After I picked my truck up I noticed the right turn signal worked. Could it be that the smoke and fine debris from the fire settled on the inside of the panel and completed the circuit? Or is it another electrical gremlin?

 

Hmm sounds like it's another electrical gremlin. But I'd replace the light switch as,
I had troubles with my dash lights goofing like your until changing the light switch..

It's just a process of elimination you have to do, then go on to the next electrical gremlins.

orich

 

I'd swap out the switch. Remember there's a "magic button" on the top of the switch body -- press that button and the **** & rod come out of the switch (otherwise you can't get the switch out of the dash).

That should take care of the lights staying on, and it should take care of being able to dim your instrument cluster lights.

The other problem seems to me to be unrelated, so do additional diagnostics after the switch swap.

 

2X Thipdar (glad to see you're still here). Sounds to me like he found a wire problem when he swapped out the heater box and fixed it.
And yes, swap out the light switch.