Dome light electrical problem

[bigd65]

Ok I have a problem. My DOME LIGHT, it comes on when I close the door and goes off when I open the door. The dome light under the dash works correctly. Here is another problem. If I turn the the headlight switch all the way to turn the dome light ON, the dome light goes off and comes back on when Ai turn it back as if I were dimming the dash light

This is the damdest thing I have ever seen, I just don't understand it.
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[cmyc5575]

Originally Posted by bigd65

Ok I have a problem. My DOME LIGHT, it comes on when I close the door and goes off when I open the door. The dome light under the dash works correctly. Here is another problem. If I turn the the headlight switch all the way to turn the dome light ON, the dome light goes off and comes back on when Ai turn it back as if I were dimming the dash light

This is the damdest thing I have ever seen, I just don't understand it.
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Lol this is kind of what im dealing with but i dont have parking lights and dash lights are dead but when i turn the head lights on the dome lights come on and wont go off. I dont know what to do to fix it i had someone tell me that i may need to change out the the light swtich and maybe that would fix the issue.

[Gordonr1973]

I think you might have a problem with the switches in the door jams if the under dash lights work coprrectly and your dome works backwards.

As I recall, when the door is open the door jam switch is extended and that completes the ground circuit necessary to turn your lights on.

Or you have a connection somewhere in reverse, have you changed any of the wires lately?

Maybe trying 2 new jam switches might be an option for you?

[hatzie]

The door jamb and headlight switches close the ground for all the floor (courtesy) and dome lights.

I'd look at the headlight and LH door switches.
This is the 1989 dome light circuit. The power pickup point varies and some trucks don't have a key buzzer... but everything else should be pretty consistent from 73-91.

[bigd65]

I have not messed with any of the lights. One other thing I did notice, if I turn the outside cab light on, the inside dome light dims alot.

I will probably just go ahead and change the door jam switch its a cheap try. I did have it out awhile back but put it back in, I was getting the dome to work. As far as I can tell, this just started. I only drive the truck on the weekends and it was last weekend that I had worked on the Poly Mounts, so I don't think the dome stayed on for a week and the battery not be dead
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[hatzie]

This is the cargo light diagram.
Its' teed into the power and ground from the dome courtesy circuit so it should stay off unless a door is open or the headlight switch is spun to the dome position.

[chengny]

The dome light and the dash illumination (back lighting for the instrument panel) are grounded through the casing of the headlight switch.

Make sure your H/L switch is tightly fastened to the steel of the dash. If that doesn't help, try a new/different H/L switch.


Also check your overall system voltage. If it is too high (i.e. more than 14 volts) your alternator may be overcharging and that will also cause the dome/dash lights to act up.

[hatzie]

It also grounds to the door switch holes. If the grounds are dodgy then you'll get odd behavior.

Does the dome light up with the door closed and the cargo light switched off?

[bigd65]

Yes it does light up. If I turn the cargo light on, the dome light dims. I'm thinking the door jam switch might be the problem, not sure, benn working on my sisters car and my daughters car all weekend. I just pulled the bulb from the dome light for now. Might mess with it today but IT'S RAINING AGAIN and it suppose to BE COLD AGAIN
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[bigd65]

Ok, I found the problem. One of the wires in the dome light, I guess over the years, was barely touching the medal where it was cut out to fit. Well over the years , wore the wire bare in a tiny spot, you could se a very minor arch spot. Blew the fuse for the Horn , the Radio and yes, reversed the polarity (?) on the dome light causing it to turn on with the door closed and off when you opened the door. I bent the wire a bit and put in a new fuse and all is well.
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