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  #1  
Old 08-05-2009, 07:32 PM
Hamish
 
Join Date: Jun 2006
Location: Epping, NH
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1993 300D electrical glitch

All of the sudden my rear intetior light and the rear door lights stay on all of the time even the the key is off (untill I take out the fuse).And the front intetior light and the flashing seat belt light stays on as long as the key is on.

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  #2  
Old 08-05-2009, 08:21 PM
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Check the rear door switches and check/clean the light control switch by the seat belt lights.
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  #3  
Old 08-06-2009, 08:58 PM
Hamish
 
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Location: Epping, NH
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The front interior light and the seat belt light are on a different circut than the rear interior lights. I can't understand why they both started having this problem at the same time. the front interior light and the saet belt light will come on all of the sudden when driving down the road or it might come on when I start the car and turn off on it's own a little while later. I took the fuse out for the rear light because that stayed on all of the time even when i shut the car off and took th keys out.
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  #4  
Old 08-06-2009, 09:20 PM
ashedd's Avatar
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I think you have some wires missing insulation thus causing them to either short to ground or with each other. Which ones... that is the big question. One way to eliminate, not fix, the problem is..

Pull the fuse block and find the fuse that that rear light circuit uses. On the backside of the fuse panel/block you will see wires that are attached to that fuse. Pull the wire off one my one until those light shut off. Tape it and leave it off. Put it all back together. You have now isolated that part of the circuit and removed it. Deal with it later or not at all.

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  #5  
Old 08-06-2009, 09:50 PM
Hamish
 
Join Date: Jun 2006
Location: Epping, NH
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Quote:
Originally Posted by ashedd View Post
I think you have some wires missing insulation thus causing them to either short to ground or with each other. Which ones... that is the big question. One way to eliminate, not fix, the problem is..

Pull the fuse block and find the fuse that that rear light circuit uses. On the backside of the fuse panel/block you will see wires that are attached to that fuse. Pull the wire off one my one until those light shut off. Tape it and leave it off. Put it all back together. You have now isolated that part of the circuit and removed it. Deal with it later or not at all.

so a short like that would not blow a fuse? but just cause the lights on two different cicuts to turn on? could this be a coinsidence that these two circuts start having this problem at the same time?
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  #6  
Old 08-06-2009, 10:06 PM
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well "short" is sorta the wrong word to use. Short would imply something going wrong and blowing a fuse. Think of more like 12 volts from another circuit powering up your light circuit because the wires are missing insulation and they touch somewhere along the line. Another scenario is "Short" the door pin switches to ground and the lights will come one.

And it can be a good ole 12 volt short to ground and not blowing the fuse because it does not pull enough current. But it could pull enough current through small wires to melt them but still not blow the fuse.

I have encountered all of the above in cars and aircraft.

But in aircraft you can have 400volts AC not short but arc to ground around jet fuel and go boom All without blowing a circuit breaker.

hope this helps.
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  #7  
Old 08-07-2009, 02:38 AM
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Quote:
Originally Posted by hame1 View Post
All of the sudden my rear intetior light and the rear door lights stay on all of the time even the the key is off (untill I take out the fuse).And the front intetior light and the flashing seat belt light stays on as long as the key is on.
The previous posts have the right idea. This sounds like two separate problems that coincidentally came along at the same time. The rear lights are due to either one of the rear door switches or the wiring in one of the B-pillars. (The rear dome light and both puddle lamps come on together when either rear door is opened.) Cars of your era had a tendency to have the B-pillar wires break and/or short after years of flexing. I have had to repair both sides in my '87, right side to fix the window motor blowing fuses and left side to fix the rear lights.

The front light is due to one of three possible problems, (a) bad front door switch, broken/shorted wiring as with the back lights, (c) failure of the transistorized timer circuit in the front dome light assembly. I would vote for (c) because my car had a similar problem when I first got it.

If you find that it is the front dome light assembly, I have a spare that should fit. PM if interested in buying it.

Jeremy

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