Exterior Trunk Lid Light Bar - Interior Trunk Light Switch SHORT?

Northhillkid

Registered
My 1994 Mark VIII has been experiencing some electrical issues that is causing a series of problems to the trunk lid exterior light panel, the interior trunk release switch, and ultimately I think it's causing the battery to drain.

I first noticed it when my trunk release button quit working. Along with the button issue, the rear deck lights began to work intermittently. When turning on the exterior running lights, the trunk lid panel would not light. However, once the trunk was opened to the point where the INTERIOR trunk light was lit, the exterior trunk lights would come on and stay on. Once the trunk was closed and re-opened, the exterior light bar would begin to alternate with the interior trunk light. As the deck lid was opened enough to trigger the interior trunk switch, the exterior light panel would shut off and vice versa as the trunk was being closed. And at this point the trunk release switch would be fully functional inside the vehicle. This sequence would last for a few minutes as I opened and close the trunk, but eventually the exterior light panel would quit working altogether and the trunk release switch inside the car is no longer functioning.

I've chased the wires but I am not able to find the trunk lid switch that triggers the interior trunk light as the trunk is opened.

THIS IS ANNOYING!!!


Any Suggestions? x(
 
RE: Exterior Trunk Lid Light Bar - Interior Trunk Light Switch SHORT?

I am not positive, but I believe that your INSIDE truck lamp runs off a mercury switch on the Gen 1. As I have a Gen 2, I'll defer this question to those that have the knowledge of the Gen 1.

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Bud Pytko - LOD Moderator
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RE: Exterior Trunk Lid Light Bar - Interior Trunk Light Switch SHORT?

Trace the wiring and look for chaffing. It has been noted in a few GEN 1's that the wire becomes chaffed and causes the light bar not to funtion. Although the switch may be a possibility, wiring is usually the culprit.
 
RE: Exterior Trunk Lid Light Bar - Interior Trunk Light Switch SHORT?

Bud's right. The trunk light is controlled by a mercury switch in the lid.

The fact that weird things happen as you're opening and closing the lid gives you a clue worth investigating.

All the wiring for the lid exterior lights, trunk light switch, and trunk release comes up the left side of the car, through an 8-pin grey connector in the trunk near the LR shock tower, and then follows the left trunk hinge to the lid.

Look carefully at the wiring in that hinge area. Cut the harness open if you have to. It's very common for the opening and closing of the trunk lid to flex those wires so many times they break. Sometimes they just go open circuit, but if more than one is broken, they may contact each other and create strange cross-circuit shorts.

Check it out!
 
RE: Exterior Trunk Lid Light Bar - Interior Trunk Light Switch SHORT?

I am going to go check it out now, thanks for the suggestions. I saw the 8 pin wire harness previously but really did nothing more than wiggle it. Because the problem is so intermittent and inconsistent makes me think that the theory of a worn wire from repeated opening and closing is the most logical explanation at this point.

I'll let you guys know what I find.

By the way, it is a dark green 1994 Mark VIII. Really nice ride I picked up from my boss a few years ago for $500. It has 218,000 miles and everything is functional, even the air suspension. I just can't let this one go... it still looks way too good.

Thanks for your help
 
RE: Exterior Trunk Lid Light Bar - Interior Trunk Light Switch SHORT?

BINGO, ground wire was hanging on by a thread. As soon as I wiggled it, it separated. I appreciate the help. I've been toying with this car on and off for four years so I'll do my best to offer any insight I can for future postings.

Thanks,

Carlo Testa
 
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