Headlight Dimmer Switch Issues

homelessduck

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The rheostat should be dead with the headlight switch pushed all the way in. The on position on the dimmer only controls the dome and cargo light.

Is it possible something in the dash is touching the rheostat and shorting it to the dome light power?

James
I've been trouble shooting it with the switch out so I'm sure nothing external is touching it.
 

homelessduck

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When you remove the stalk it’s always closed..
I meant with the switch removed from the dash. Not with the stalk pulled out. Or am I missing something? It's been hard to take everything in with my toddler ... doing toddler things LOL
 

hacked89

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I meant with the switch removed from the dash. Not with the stalk pulled out. Or am I missing something? It's been hard to take everything in with my toddler ... doing toddler things LOL
I thought you meant you had the stalk out and were wondering why everything was lit haha
 

franklin2

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It does have an aftermarket stereo in it , but it turns off with the key off , and the dimmer doesn't affect its brightness at all. I guess it would be worth a shot to pull it out and have a look just in case.
The radio is downstream and has the blue/red wire feeding it. You unplugged the wiring plug to the headlight switch and the lights go out. So it's something right there at the headlight switch.
 

homelessduck

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I pulled the radio fuse just to make sure because I am running out of ideas. It didn't change anything of course. I inspected each wire at the plug and they all look great. I pulled each wire from the plug , one at a time , to see if I could isolate the issue. No changes. I have no clue what it could be other than a bad switch. I tried another new switch that I had ( it wouldn't keep the push/pull rod in ) and it does the same thing. :dunno
 

homelessduck

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Is this the correct wiring diagram? My plug is wired differently but it says it's for a '94 which should be the same. I will have to double check but I'm pretty sure my tan/white wire goes to pin R which runs straight to the rheostat.:dunno
 

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franklin2

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You unplug the complete headlight switch plug and the lights go out. But you take each wire off individually and they stay on? That doesn't make sense somehow.
 

franklin2

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My cluster illumination was not working but everything else controlled by the switch worked fine. I finally got around to replacing the switch today. The cluster illumination will not turn off now. Ignition off , key out , cluster stays illuminated , and the dimmer portion of the switch gets hot. I can dim it all the way down , but the lights never turn off. The harness and plug is not melted at all. I have tried several different switches with the same results. It should be keyed on power , not constant to the cluster illumination right?
This is your original post. Everything was working correctly except the cluster lights, until you changed the switch. What happens if you put the old switch back in?
 

homelessduck

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You unplug the complete headlight switch plug and the lights go out. But you take each wire off individually and they stay on? That doesn't make sense somehow.
The only wires that make any difference with the illumination is the Tan/White wire ( Pin R ) and the Blue/Red ( Pin I ) . Removing the others wires made no difference. I was trying to see if anything was cross feeding power to those pins somehow.
 

homelessduck

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This is your original post. Everything was working correctly except the cluster lights, until you changed the switch. What happens if you put the old switch back in?
Unfortunately I tossed the old switch. However, I honestly don't know if the illumination has ever worked in this truck since I've owned it. It's been out for awhile and I don't remember it actually going out so it may have been that way since I bought it. It was a small issue that didn't bother me so it took me awhile to get around to fixing it. I am skeptical that the pins are switched , but if that diagram is correct then I'm pretty sure they are. I will be looking at it shortly to confirm.
 

franklin2

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The only wires that make any difference with the illumination is the Tan/White wire ( Pin R ) and the Blue/Red ( Pin I ) . Removing the others wires made no difference. I was trying to see if anything was cross feeding power to those pins somehow.
This makes sense. The tan/white is the feed wire from the fuse box for the running lights and the dash lights. The blue/red is the dimmable dash light wire leaving the switch.

The problem has to be in the switch. You may be getting the wrong one, I don't know. I do know Ford is famous for changing things mid-year and making half-year changes.

If you want to just get it going,, you could cut the blue/red wire at the switch and tie it to the brown wire which is the marker light power wire. Your cluster and dash lights will be bright all the time, but they should cut on and off.
 

homelessduck

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Sooo..It's fixed! It turns out the tan/white wire and the brown wire were switched. So the illumination was receiving constant 12v. Apparently with this configuration everything still turns on , the illumination just won't turn off. :rotflmao I vaguely remembered having a wiring issue with the visor awhile back and posting about it here. So I found the thread and noticed I mentioned de-pinning the plug while troubleshooting. I also mentioned which pin the brown wire was supposed to be on.. so obviously the smart guy that switched the wires was in fact me! :bail
 

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