1980 Electrical Problem

When my Corvette (coup) gets wet (rain, wash) the interior dome light comes on and will not shut off until the affected area drys out. Sometimes this takes hours. It has been suggested that the dash light
switch is somehow getting wet (under the dash) but I cannot find water inside of the car on that side, except under pressure (wind/hose) water will leak through roof panels on both sides, but does not run toward the dash on either side. I believe the only other items on that particular circuit would be the lower courtesy lights on both sides and the door switches and have replaced the switch on the passenger side without luck. I'm thinking a short would blow a fuse but to date that has not happened. The dome light has been disassembled but shows no sign of ever being wet. Any ideas as to how I might go about solving/tracing this problem? Referrals to other Corvette related websites might also be helpful.
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Russ wrote:

Dome light comes on with "dampness" but courtesy lights do not -- is that correct?
--
…PJ
’89 HookerCar, ’02 E-blu 6-spd Coupe
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You are correct. The problem lies exclusively with the dome light. As you probably know, by design it has a delay feature built in to it that under normal circumstances keeps the light on for about twenty seconds after exiting the vehicle. But when "something" gets wet it will not shut off. As I write this the car is with a reputable mechanic who is just as perplexed as I am.
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Russ wrote:

I took a quick look at the wiring diagram. The left door switch has three terminals and the right, two terminals. IIRC, my '79 Pontiac alsi had two switches and I had a problem with the driver's side switch--never traced out the extra wire though.
I've got to make a quick run out to a site in the desert. When I get back I'll trace out those wires and see if a leak down into the left door pillar might be the culprit. Ditto the harness connectors.
Diode, bless his cussed being, was an expert on those delay modules. Wish he were here now.
CUL.
--
…PJ
’89 HookerCar, ’02 E-blu 6-spd Coupe
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Russ wrote:

Easy answer: After a "dumb stare" at the schematic I'd meander to the rear of the car and check out the wiring and socket for the spare tire lamp. Looks like you might be picking up a ground on the white wire back there. Possible "damp" area (:-)
Just for info, the three wires from the Left door switch provide grounds as follows:     White -- ground for the dome light circuit and the courtesy delay module     Tan -- ground that goes via a contact in the steering column to the seat-belt & ignition key warning buzzer (sounds when the door is open and the key is in the ignition)     LtBlue -- ground to anti-theft system
Right door switch is same without the (tan) key signal.
Hard answer: If this doesn't do it and key alarm and anti-theft are working OK then I'd look at an an eight-cavity harness connector (p/n 8900441) under the dash. The White wires are the ones that carry the grounds to the lamps. Other colors on that connector are Yellow, Dark Green, Pink, Light Green, Orange and Light Blue. The small-harness side of that connector heads for the rear body and has the two white wires that go to the dome light and the spare tire light. (All of this assumes that my schematic is the same as the harness in the car.)
Extra hard answer: The problem is in the delay module or in wiring on the 'large-harness' (dash) side of the above connector -- one of those jobs no one wants -- unless we can find Diode to supervise and there's unlimited beer.
Let us know if you found something.
--
…PJ
’89 HookerCar, ’02 E-blu 6-spd Coupe
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Thanks for the info. I will pass this along to my mechanic and will advise you of success/failure. I'm probably going to have to purchase wiring diagrams for them as they have indicated what they have appears to be inadequate. Any advice as to who produces the best after market product?
PJ wrote:

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