Electrical: Strange Avanti Electrical Problem

[PACKERBACKER]

While trying to figure out why one of my horn pigtails did not get current to it, I came across an interesting thing. With the negative cable of the battery disconnected (there is a jumper to allow an electric fan to operate after the engine is shut off) I touched the probe on a test light to the radiator and the light came on. The clip from the test light was connected to the negative battery terminal. The light would also come on if I touched the probe to the engine. When I connected the negative cable to the battery and tried touching the probe to the radiator or engine the light did not come on then. Recently I had checked the fuses because the interior lights were not coming on while opening the doors. The fuse was blown so I replaced it and noticed that the clock fuse was missing so I installed one. After doing this and leaving the battery connected overnight, I noticed that when I drove the car that the ammeter looked like it was charging higher than normal. I usually disconect the negative cable when I park the car in the garage. When I did not disconnect it the battery was discharged enough so it would not turn over the starter after three days. I believe the clock is the problem, it still does not work with the new fuse and I suspect that it is a constant drain. Tomorrow I will go through the fuses and see if this is the case. I did put a new ground from the engine to the frame when I rebuilt the engine last year. Anybody have any other ideas about the test light coming on with the negative cable disconnected?

[mapman]

It sounds like you are just completing the circuit through the test light. If the fan switch is on or the clock contacts are engaged or anything else is on it just needs the light to complete the circuit. It may be too much resistance to activate anything else.
Rob

[studegary]

If the contacts in the clock are stuck closed, there will be a constant drain on the battery. It sounds like the contacts need to be cleaned. Stuck clock contacts should blow a CORRECT amperage fuse. Until you solve your other electrical issues, I would just leave the clock fuse out.

[PACKERBACKER]

Pulled the fuses one at a time till the test light went out and found out it is the fuse for the cigar lighter and dome light. Both of these items seem to work well so I guess I'll have to look into this a little further.

[studegary]

Pulled the fuses one at a time till the test light went out and found out it is the fuse for the cigar lighter and dome light. Both of these items seem to work well so I guess I'll have to look into this a little further.

I would guess the cigarette lighter. Disconnect it at the back of the unit and see if that works.

[PACKERBACKER]

I thought the same thing as Gary and tried disconnecting the wires to the lighter first but that did not make the test light go out. The next thing I did was to disconnect all of the plugs to each of the interior lights and that didn't work either. I discovered that the trunk light is on the same fuse and someone in the past had taken the wiring that contains the mercury switch and let it hang loose so the switch was not turning off. After clipping it to the trunk lid the test light goes out when the trunk is closed and goes on with it up. That explains why the battery was draining down. I recently had plugged a gps into the lighter receptical and it worked fine. Turns out the fuse blows when I try to use the lighter. I had bought a replacement lighter and the receptical in the past from a parts store but it seems to short out when pushing in the lighter. Guess that I'll need to mess with it tomorrow and try to get it to not blow the fuse. I also found that two of the on/off switches on the dome lights must have a slight short in them also because the test light and that interior light flickers on and off when the switches are wiggled a bit in the on position. Maybe I can clean the switch with contact cleaner and fix it, though it might not be a real problem since it looks like the mercury switch was the real culprit.

[studegary]

Thanks for reporting what you found.

[PACKERBACKER]

Thank you Gary for some thoughts on this matter. I still can't get the fuse for the lighter to not blow when you push the lighter in to use it. If I push the lighter in first and then connect the battery teminal to the battery post the lighter works fine. I tried another receptical and it does the same thing. The contact cleaner did seem to work pretty good on the interior light switches. It sure pays to check around to get a good price. Two of the local parts stores wanted $5.99, one wanted $7.99 and I ended up buying the exact same thing, CRC brand for $3.89 at Farm and Fleet. Shouldn't surprise me, they almost always do have the best prices!