Interior lights dont work, what did I fry?

ZPmadA · 06-24-2005, 06:54 PM

A while back I was messing with my climate control. I pulled it out and put it back in, but while I put it back in a plug was disconnected (the one that sends power to illuminated the climate control) So my interior lights went on (minus the climate control), and smoke started coming from my dash on the left side of the steering wheel. I noticed my dimmer adjuster and fog light switch (they are next to each other) were hot. I'm guessing I fryed my dimmer with the excess power? When my climate control was disconnected and not lighting up, i'm assuming I had too much excess power and the weakest thing fried. Whats first to go in the event of an over load, the dimmer? Why didnt my fuse go? If I didn't shut everything down this could have turned into a fire arent fuses supose to prevent that? I believe there is supose to be a 15amp fuse for the interior lights but for whatever reason there is a 30 amp fuse, and its still fine so I know the fuse isnt the reason my interior lights don't light up. I have a 1986 944 turbo. I'm getting ready to order a new dimmer, but I want to make sure.

livewirevoodoo · livewirevoodoo's Garage

Quote:

Originally posted by ZPmadA
I believe there is supose to be a 15amp fuse for the interior lights but for whatever reason there is a 30 amp fuse

That might be why it burnt instead of blowing the fuse. I'd switch it back to the spec'd fuse just to be on the safe side.

carsonmx114 · 06-24-2005, 08:41 PM

the power to all the dash lights flows through the dimmer. when it's adjusted to full bright the dimmer is short circuited, at anything less than full brightness the power runs through a adjustable resistor. this resistor eats up voltage to dim the lights. when your climate control wires were left unpluged they must have shorted out and since the fuse was to big the resistor was the weak link in the circuit. if you don't dim your dash lights you can just connect the two wires together behind the dimmer and bypass it, but be sure to change back to the correct fuse.

livewirevoodoo · livewirevoodoo's Garage

i'd check the rest of your fuses while you're at it, if you haven't already. sound investment of $10.

ZPmadA · 07-01-2005, 01:32 PM

Quote:

Originally posted by carsonmx114
the power to all the dash lights flows through the dimmer.

How about before the dimmer? I just got a used dimmer off ebay and installed it. Still no interior lights. I tried touching wires to bypass the dimmer and no lights. Looks like I have an electrical nightmare ahead of me

If the positive is all ok, is there a weakspot in the ground that could be toast? If I remember correctly, after the smoke incident (burning the dimmer) I had interior lights for about a week. They occasionally went out for a couple seconds and then came back on, until finally they just went out.

I checked all the fuses and they are all up to spec minus 1 10amp fuse that should be a 7.5amp

carsonmx114 · 07-01-2005, 05:50 PM

you may have two unrelated problems, my 86 951 developed a intermitant interior light problem and after a quick check i found a bad connection in the door switch. do you have a test light? if so check for power at your dimmer. i feel sure the power to the dimmer comes from the headlight switch, i wish i could tell you more but my service manual is on cd and the sides of the wiring diagram are chopped off. it may be that the power to the headlight switch goes through a relay first and the relay is bad. i don't think the interior lights and the dash lights would share power unless they're connected before the headlight switch. the interior lights have two grounds, one from the door switch and one to chassis ground through the switch on the light. will the interior lights work with the switch on the light? i'll keep looking on my wiring diagrams and try to find a good picture of the dimmer circuit. post back if you have any new developments.

ZPmadA · 07-01-2005, 09:09 PM

Quote:

Originally posted by carsonmx114
you may have two unrelated problems, my 86 951 developed a intermitant interior light problem and after a quick check i found a bad connection in the door switch. do you have a test light? if so check for power at your dimmer. i feel sure the power to the dimmer comes from the headlight switch, i wish i could tell you more but my service manual is on cd and the sides of the wiring diagram are chopped off. it may be that the power to the headlight switch goes through a relay first and the relay is bad. i don't think the interior lights and the dash lights would share power unless they're connected before the headlight switch. the interior lights have two grounds, one from the door switch and one to chassis ground through the switch on the light. will the interior lights work with the switch on the light? i'll keep looking on my wiring diagrams and try to find a good picture of the dimmer circuit. post back if you have any new developments.

whoops my mistake I ment dash lights, not interior lights. My interior lights are fine.