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Discussion Starter #1
On my coupe, when I depress both door jamb switches, the dome light dims. What could cause this? Bad headlight switch? Open ground somewhere? I replaced both door jamb switches and when I replaced the passenger side, the light finally went out when I closed the door. Last night, it came back on. I depressed the passenger side and now it's not working again. I think I may have an open ground on the passenger side, but I am not 100% sure. Can I check with a multimeter? Thanks for any and all help!
 

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an open ground would keep the light from working, not keep it on. the dome light is controlled by a ground supplied by one of three things - driver door switch, passenger door switch or the headlight switch. the 12v is always supplied to the dome light (assuming fuses and wiring are good). so if your light is staying on, something is providing a ground that should not be. white wire from headlight switch is the ground from it when you turn the knob all the way to one end. pull both door switches and see if the light works as advertised with them isolated from grounds. some reproduction dome light housings have issues with applying a ground through the mounting screws.
 
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Discussion Starter #5
an open ground would keep the light from working, not keep it on. the dome light is controlled by a ground supplied by one of three things - driver door switch, passenger door switch or the headlight switch. the 12v is always supplied to the dome light (assuming fuses and wiring are good). so if your light is staying on, something is providing a ground that should not be. white wire from headlight switch is the ground from it when you turn the knob all the way to one end. pull both door switches and see if the light works as advertised with them isolated from grounds. some reproduction dome light housings have issues with applying a ground through the mounting screws.
Thanks for informing me of that. Good to know now. I did replace the dome light housing 7 years ago with a reproduction and if I remember correctly, it all started then. But, I can't recall. Can you recommend a dome light housing? I'll check the other things first of course and report back!
 

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Discussion Starter #7
There have been reports of replacement dome light housings getting grounded through the chrome plating.
You might want to test by removing the screws and letting the light hang down.
Thanks, Dean. Will do that. I removed both door jamb switches and light is still on. So, it must be grounding. With door jamb switches in and headlight switch knob turned all the way, it just dims the light.:frown2:
 

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Discussion Starter #8
There have been reports of replacement dome light housings getting grounded through the chrome plating.
You might want to test by removing the screws and letting the light hang down.
I can confirm those reports. Just removed both screws, light went out. I was actually getting sparks when taking the second screw out and the housing starting to fall! :surprise: I'll have to find a good original housing or one with no chrome plating on it. That's just downright dangerous those screws grounding themselves to the housing. Thank you, Joe, Dean and Rich! I really appreciated it! And Rich, turning the headlight knob all the way to left turns the dome light on to the right, off. Thanks again guys!:thumbsup:
 

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There was also a Chevrolet Bulletin covering the plating (or what they called "metalizing") on the dome light housings and while yours was staying on, this was due to the ground side but if the issue was still on the ground side but it had a lot of resistance, you might not see the bulb illuminating but with an ammeter the dome light circuit could stil be drawing power leading to a dead battery after time.





Jim
 

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Discussion Starter #11
There was also a Chevrolet Bulletin covering the plating (or what they called "metalizing") on the dome light housings and while yours was staying on, this was due to the ground side but if the issue was still on the ground side but it had a lot of resistance, you might not see the bulb illuminating but with an ammeter the dome light circuit could stil be drawing power leading to a dead battery after time.





Jim
Interesting. Thanks, Jim!:thumbsup:
 
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