Headlight switch failure caused other gremlins...
08-12-2006, 10:57 PM
#1
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Headlight switch failure caused other gremlins...
In the parking lot at work Thursday night, I started the car to go home. As usual, I flipped on my lights, rear defogger, and I started to defrost the foggy windshield- probably too high a load at idle. The radio was also on. After a few seconds, everything electrical dimmed. I assumed the radio fuse blew, as it did that once before. However, the radio and dash lights came back on. The switch melted in the on position. I have a new switch and Rennbay wiring harness on order to fix that ASAP. I drove home on the foglights; luckily, my commute is 100% backroads.
The bad part: The blower fan, gauge lights, engine fans, defroster, wipers, and headlights do not work. The radio, parking lights, brakelights, foglights, and windows work. Changing fuses with new ones does nothing.
I don't see anything on this in the archives, but maybe I didn't look hard enough. Has this happened to anyone? My dad (an electrician) thinks there is a fuseable link somewhere by the battery to protect it. We've never had true electrical problems on the car, so I'd appreciate it if someone more familiar with the 944 electrical system could comment. Thanks.
I also thought relays, but Clark's says that one radiator fan should come on at the appropriate time even if the cooling fan relay failed. I don't *think* it melted any wiring, as I didn't see smoke.
The bad part: The blower fan, gauge lights, engine fans, defroster, wipers, and headlights do not work. The radio, parking lights, brakelights, foglights, and windows work. Changing fuses with new ones does nothing.
I don't see anything on this in the archives, but maybe I didn't look hard enough. Has this happened to anyone? My dad (an electrician) thinks there is a fuseable link somewhere by the battery to protect it. We've never had true electrical problems on the car, so I'd appreciate it if someone more familiar with the 944 electrical system could comment. Thanks.
I also thought relays, but Clark's says that one radiator fan should come on at the appropriate time even if the cooling fan relay failed. I don't *think* it melted any wiring, as I didn't see smoke.
08-13-2006, 12:22 PM
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Do you have the electrical schematics for your car? If not you can get them here:
http://www.pelicanparts.com/944/elec...l_diagrams.htm
Also get the Haynes 944 book. It has a slightly different interpretation of the same schematics.
There are three large red wires that come off of the side of the positive battery terminal. These feed all of the electric into the car. I would remove these, clean them and the terminal and put them back onto the stud. Also clean the ground to the chassis and the chassis to the engine.
You will need to inspect all of the wiring under the dash that comes into contact with the headlight wiring. You need to inspect the headlight wiring at the front of the car where it flexes to the headlights. Please remove the ground wire to the battery when you inspect the headlight wiring. You can get caught up in the headlight rotation mechanism if they decide to open or close.
The headlight switch is a direct feed from the battery (one of those three red wires) so if/when it shorts out it can cause a lot of damage by melting the wires around it's feed wire. Yes it's a PITA to get under the dash. Some remove the drivers seat which can be a PITA too.
http://www.pelicanparts.com/944/elec...l_diagrams.htm
Also get the Haynes 944 book. It has a slightly different interpretation of the same schematics.
There are three large red wires that come off of the side of the positive battery terminal. These feed all of the electric into the car. I would remove these, clean them and the terminal and put them back onto the stud. Also clean the ground to the chassis and the chassis to the engine.
You will need to inspect all of the wiring under the dash that comes into contact with the headlight wiring. You need to inspect the headlight wiring at the front of the car where it flexes to the headlights. Please remove the ground wire to the battery when you inspect the headlight wiring. You can get caught up in the headlight rotation mechanism if they decide to open or close.
The headlight switch is a direct feed from the battery (one of those three red wires) so if/when it shorts out it can cause a lot of damage by melting the wires around it's feed wire. Yes it's a PITA to get under the dash. Some remove the drivers seat which can be a PITA too.
08-14-2006, 03:21 PM
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Culprit appears to be a destroyed ignition switch. Using a multimeter, we found that some of the contacts measured as open circuits when the switch was at both off and on positions. A new one is on order, and I'll see tomorrow if it fixes it. Thanks.
