1990 GMC Suburban No interior lights, cigarette lighter or

CARDUO6988

MEMBER
1990 GMC SUBURBAN
V8
4WD
AUTOMATIC
200,000 MILES

Actually, I have 2 Suburbans with the same problem. No interior lights, horn, radio or cigarette lighter. We bought both at the same time. One of them was working fine when we got it, but 3000 miles later the problem popped up without warning. They keep blowing the dome light fuse. Can't find any bare wire or scortch marks. I know it's probably a short somewhere, but I have no idea where to start looking. Any help would be greatly appreciated.

Tuesday, August 31st, 2010 AT 8:02 AM

5 Replies

RACEFAN966

MECHANIC
5,029 POSTS

Ok so lets see what I can do to help. Does it blow the fuse now right away or does it take a bit? Do you have a digital multi meter to do some checking if needed? What I would like you to do first is a process of illimination ok. Leave out the dome light does the fuese blow, unplug the cigarete lighter does it blow. Lets start there and get back to me with your findings.

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Tuesday, August 31st, 2010 AT 10:24 AM

CARDUO6988

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3 POSTS

#1 - unplugged lighter. Still blew.
#2 - unplugged radio. Still blew.
#3 - unplugged both dome lights, hasn't blown yet.

Usually it takes 12-15 minutes for the fuse to blow, but it's been over 30 minutes and it's still going. FYI: One of the bulbs I pulled is black on the inside but still lights up. Could this be the problem?

Also, I do have access to a meter if needed.

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Tuesday, August 31st, 2010 AT 11:24 AM

RACEFAN966

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5,029 POSTS

Ok great we have now figured out what circuit it causing the problem. Now I need to know if you have a digital multi meter and if you would be able to do some testing? If so then I will include wire colors and locations. We either have a bad dome light (not the bulb) or a bad door pin switch or a wire grounding out somewhere in the circuit. Get back to me with what you want to do and we will go from there.

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Wednesday, September 1st, 2010 AT 9:54 AM

CARDUO6988

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I can test anything you want me to. Just tell me what I need to know. I can normally fix anything without much problem, but electrical shorts I don't have much experience with. Just say the word.

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Thursday, September 2nd, 2010 AT 7:36 AM

RACEFAN966

MECHANIC
5,029 POSTS

Ok what I would like you to do is remove the drivers side door pin switc that turns the light on. Ohm it then depress it and ohm it. Let me know what you find, we will start here as we have to start somewhere. Also here is pic of the wiring that includes the dome light circuit hope it helps.