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Old Oct 18, 2010 | 09:21 AM
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Default C3 interior lights

Monkeying with electrical is alive and well. Previous owner did something. No interior lights, no dome or underdash. Open either door or hit the headlight controller - Nada. Looked at service manual. Looks like when any of the three switches (doors or headlight) is activated, they just provide a connection to ground. Since none of these make any light turn on, I wonder if there is a break farther upstream. Diagram shows these three lights come to a common splice point, this splice point then branches out to the three switches. I do have 12V at the dome light bulb connector. ANyone have any experience in knowing where this splice point might be or how to backtrack the harnesses to find a break??
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Old Oct 18, 2010 | 10:39 AM
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If you have 12v on the orange try grounding one of the white wires and see if the lights come on.
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Old Oct 18, 2010 | 11:14 AM
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Originally Posted by ...Roger...
If you have 12v on the orange try grounding one of the white wires and see if the lights come on.
Have thought about that, but ground where?? If I ground at the bulb, it should work. Guess I could back track and see what I can find in the dash. But i guess depending on what bulb comes on, it might tell me if I am in front of or behind the splice. The way I understand the diagram, the splice point is how any switch can get all bulbs to turn on. Since no bulb comes on from any switch, would that not indicate there is a break somewhere upstream mainly around the splice? If I had a bad switch or a wire break between the switch and the splice point, one of the other switches would turn on the bulbs. I am DOA on all bulbs. Will try that and if I can find several white wires, will try them all.
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Old Oct 18, 2010 | 01:43 PM
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If you just pull the bulb and socket down,you should be able to take grounded piece of wire and touch the end to the brass case of the bulb. If it has power that should ground and light the bulb and most likely all your bulbs will light.

What year are you working on ? When you said dome, I am thinking 77 and up , that brings into play the delayed system. Your door switches go there but the HL switch white wire does not.

Try the grounding,that will tell us if you have power and if they all work,then we can search for the interruption in the ground. Could be as simple as someone unplugged the delay relay.
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Old Oct 18, 2010 | 01:57 PM
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Originally Posted by ...Roger...
If you just pull the bulb and socket down,you should be able to take grounded piece of wire and touch the end to the brass case of the bulb. If it has power that should ground and light the bulb and most likely all your bulbs will light.

What year are you working on ? When you said dome, I am thinking 77 and up , that brings into play the delayed system. Your door switches go there but the HL switch white wire does not.

Try the grounding,that will tell us if you have power and if they all work,then we can search for the interruption in the ground. Could be as simple as someone unplugged the delay relay.
OK, will try. It is a 79. I think they have worked on all the issues they told me about when I bought the car. Nothing on AC worked, but I have finally got blower going and the vac switch replaced and air now coming out of vents when move lever to where you want it. I noticed inside the shift console portion, a cut black ground wire. It is unknown if this is a cut wire they added for like a different radio or if it is a stock wire. It also appears they had the side kick panel on driver side off and maybe pulled part of the dash loose on driver side. Wonder if they were trying to get to something, like the light switch. Oh well, I feel they did not have a service manual and were flying by the seat of their pants. I will get it going. Thanks. Will keep you posted on what I find.
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Old Oct 18, 2010 | 02:03 PM
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You might get lucky with the 79 , the delay relay is easy to get to over behind the glove box,the whites plug in there so if they are unplugged that could be it.
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Old Oct 18, 2010 | 02:57 PM
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Originally Posted by ...Roger...
You might get lucky with the 79 , the delay relay is easy to get to over behind the glove box,the whites plug in there so if they are unplugged that could be it.
Yep, see if you have one of these. Most 79s had the delay feature. Remove the orange thing and you'll have no lights. When faulty they seem to keep the lights ON.
There is a way to bypass it.
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Old Oct 18, 2010 | 03:24 PM
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Originally Posted by KapsSA
Yep, see if you have one of these. Most 79s had the delay feature. Remove the orange thing and you'll have no lights. When faulty they seem to keep the lights ON.
There is a way to bypass it.
AH-HA!! I think I have seen that delay. I was in there working on AC and I wondered what that was. Will do, I will check it out.
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Old Oct 18, 2010 | 05:14 PM
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There should be a female white and a male white , you know what to do with that !!!
Plugging the 2 together will bypass the relay.
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Old Oct 19, 2010 | 09:24 AM
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Originally Posted by ...Roger...
There should be a female white and a male white , you know what to do with that !!!
Plugging the 2 together will bypass the relay.
Good News!! Kind of emabrassed, I am glad you mentioned what the delay does when it fails, lights are ON. All the bulbs were burnt out. Why did I just assume they or at least one would be working. Well, put in a new bulb and it is ON, all thetime. Remembering what you said on the delay, I pulled it out. Shorted the whites together, and that is it!!! Thanks a bunch. Sure am glad u mentioned the delay.
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Old Oct 19, 2010 | 04:23 PM
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Wilcox sells the little circuit board that goes inside the orange case if you're so inclined.
I think about $25.
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