When Dome lights work (finally)!
Well I've had some success solving the minor but nagging electrical problems that have been little mysteries since I got the car.
Dome Light.
The domelight wiring in my case was attached to the mirror. The problem has been that when I test the voltage on the hot wire, it was varying between 2 - 8 volts. I thought maybe this was a short in the channel that was causing some of the other problems. So I connected a know good wire to the fusebox terminal and connected the wire to the terminal on the mirror. The dome light worked! The driver's side door switch also worked, and the light would go on and off. So I thought then that I'd need to thread a new wire through the windshield channel. Chris is right you need a stiffer wire, like an old heater cable or something to thread it through. Having chopped up my old heater cable for reaming out the heater control cable channel, I had nothing to use. So I did a continuity test on the existing wire. The wire tested fine. I wiggled the wire at both ends and everything seemed fine. Then I reattached the wire to the mirror and the dome light worked fine. So I figured problem solved and put the mirror back in place, but then the dome light wouldn't work again. I removed the mirror again and detached the wire, this time the wire connector broke. Hum...maybe was part of the problem. So I attached a new connector, but still low voltage again. I decided to check the end where the wire attaches to the fusebox. When I wiggled it, the voltage would sometimes hit 12 volts and sometimes would drop to 0. One of the problems with this connection was that a Y branch had been attached to this fuse terminal to allow for connecting the memory wire for the radio ( more about this next.) So I redid the wire connector on this end, took off the Y and attached the wire directly with a good solid connection. Now I have a good 12 volts even with the mirror attached. So the dome light now works just fine.
Radio Memory
Now the radio has sometimes had a memory (channel presets, and especially the radio clock) and sometimes not. With no apparent reason everything would reset, it would loose its memory. The memory wire is seperately fused and was attched to fuse #9 along with the dome light. So I decided to use the clock wire from the old clock (which doesn't work anyway) and connect it to the radio memory wire. (The old clock wire had a good solid connection direct to the battery terminal wire.) Now the radio has a good memory. The big problem for both the radio and the dome light was the Y connector's poor connection to the terminal.
Fuel guage
The fuel guage has been jumping around sometimes reading high and sometimes low. Got to be a loose connection somewhere! So I tested the continuity on the sending unit wire. Sure enough when you bent the wire a little bit the ohm meter would jump. In fact it would jump just like the fuel guage. Problem solved, just replace the wire. Now the fuel guage seems stable and accurate but I'll have to watch it over the next week to see how it goes.
The multitester has really paid for itself. Being able to test continuity and voltage levels is a great aid to troubleshooting. Basic rule of thumb is don't assume anything, and test, test, test.
Dome Light.
The domelight wiring in my case was attached to the mirror. The problem has been that when I test the voltage on the hot wire, it was varying between 2 - 8 volts. I thought maybe this was a short in the channel that was causing some of the other problems. So I connected a know good wire to the fusebox terminal and connected the wire to the terminal on the mirror. The dome light worked! The driver's side door switch also worked, and the light would go on and off. So I thought then that I'd need to thread a new wire through the windshield channel. Chris is right you need a stiffer wire, like an old heater cable or something to thread it through. Having chopped up my old heater cable for reaming out the heater control cable channel, I had nothing to use. So I did a continuity test on the existing wire. The wire tested fine. I wiggled the wire at both ends and everything seemed fine. Then I reattached the wire to the mirror and the dome light worked fine. So I figured problem solved and put the mirror back in place, but then the dome light wouldn't work again. I removed the mirror again and detached the wire, this time the wire connector broke. Hum...maybe was part of the problem. So I attached a new connector, but still low voltage again. I decided to check the end where the wire attaches to the fusebox. When I wiggled it, the voltage would sometimes hit 12 volts and sometimes would drop to 0. One of the problems with this connection was that a Y branch had been attached to this fuse terminal to allow for connecting the memory wire for the radio ( more about this next.) So I redid the wire connector on this end, took off the Y and attached the wire directly with a good solid connection. Now I have a good 12 volts even with the mirror attached. So the dome light now works just fine.
Radio Memory
Now the radio has sometimes had a memory (channel presets, and especially the radio clock) and sometimes not. With no apparent reason everything would reset, it would loose its memory. The memory wire is seperately fused and was attched to fuse #9 along with the dome light. So I decided to use the clock wire from the old clock (which doesn't work anyway) and connect it to the radio memory wire. (The old clock wire had a good solid connection direct to the battery terminal wire.) Now the radio has a good memory. The big problem for both the radio and the dome light was the Y connector's poor connection to the terminal.
Fuel guage
The fuel guage has been jumping around sometimes reading high and sometimes low. Got to be a loose connection somewhere! So I tested the continuity on the sending unit wire. Sure enough when you bent the wire a little bit the ohm meter would jump. In fact it would jump just like the fuel guage. Problem solved, just replace the wire. Now the fuel guage seems stable and accurate but I'll have to watch it over the next week to see how it goes.
The multitester has really paid for itself. Being able to test continuity and voltage levels is a great aid to troubleshooting. Basic rule of thumb is don't assume anything, and test, test, test.
posted by Doug Druckenmiller at 11:03 AM
1 Comments:
I may have to pick up a brake cable from my neighborhood bike shop for threading that wire to the dome light. It's in the same spot as yours; right above the rear view mirror.
It is a good feeling to see the electrical issues get narrowed down! After I get the dome light fixed I just need to figure out the rear defrost and the seat belt light. I know there's just a short in the seat belt light as I've seen it come on sometimes when I get in at first and turn the wipers on. Funny.
So, with the wiring fixed and when VW Man gets my motor running right, the only thing left really is body work! Wee! Boy, I'm really dreading that one as I keep reading accounts of people who started in on their Ghias for rust repair, priming and re-painting and founds boku problems.
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