Electrical issues drives me nuts.

[sdmustangrider]

Well, I did some testing with the light tester first thing in the morning. Started to play with a bunch of wires to see if I would be able to find something. I decided to mess around with the starter ground wire to the solenoid and all of a sudden I got the light to turn off, meaning I might've found the cause. I kept jiggling it and the light was flickering. When I actually got the light to turn off, I was moving the wire side to side where there is a hanger for the ground/starter wire. Now I'm wondering maybe the insulation in the hanger is bare and might've opened up the wire? I didn't really get to check because my car is at my pop's house and I'm at home watching the kids. But first thing tomorrow I'm going to raise the car up and I'm hoping with the light turning off after messing with the starter ground, that's the issue. Should do more testing tomorrow. For the hanger if that's what's causing it (possibly wire rubbing on metal), do stores sell that part or is that something from NPD?

[sdmustangrider]

Well, I'm kind of bringing this thread back as an update. Maybe someone can help a bit out here. Last weekend, my buddy and I for about 2 hours finally found 2 possible sources of why my chassis has 12 volts when my battery ground is disconnected and the positive cable connected. When I was holding the volt meter on the chassis, my buddy disconnected the dome light, making the voltage drop from 12 to 6 volts. Of course when he connected it, it went back to 12 volts. So we kept it disconnected and still showing 6 volts. Now we had to figure where the 6 volts are coming from. So we thought we checked the whole engine compartment, but I saw the other half of the harness to the alternator. I decided to mess around with it, and found a small kink in one of the wire. After fiddling with it, the voltage dropped to 0 which is what we want. At the time, we volt tested all of the wires on the headlight-alternator harness which one of them was putting the 12 volts out.

As of today, I put the new harness on and tested the wires on the harness and now it indicates 0 volts. But, my chassis still indicates 12 volts. Since we found out the dome light switch dropped 6 volts when disconnected, can we assume that the switch might be the lone problem now? The 2 wires to the ammeter are disconnected too.

[bartl]

Originally Posted by sdmustangrider

Well, I'm kind of bringing this thread back as an update. Maybe someone can help a bit out here. Last weekend, my buddy and I for about 2 hours finally found 2 possible sources of why my chassis has 12 volts when my battery ground is disconnected and the positive cable connected. When I was holding the volt meter on the chassis, my buddy disconnected the dome light, making the voltage drop from 12 to 6 volts. Of course when he connected it, it went back to 12 volts. So we kept it disconnected and still showing 6 volts. Now we had to figure where the 6 volts are coming from. So we thought we checked the whole engine compartment, but I saw the other half of the harness to the alternator. I decided to mess around with it, and found a small kink in one of the wire. After fiddling with it, the voltage dropped to 0 which is what we want. At the time, we volt tested all of the wires on the headlight-alternator harness which one of them was putting the 12 volts out.

As of today, I put the new harness on and tested the wires on the harness and now it indicates 0 volts. But, my chassis still indicates 12 volts. Since we found out the dome light switch dropped 6 volts when disconnected, can we assume that the switch might be the lone problem now? The 2 wires to the ammeter are disconnected too.

Let me guess. You're connecting one lead of the voltmeter to the battery negative post and probing the harness with the other lead? If you do this you're using your meter as the ground wire. If you're NOT connecting the meter this way, please tell us how you ARE connecting it, because it's also wrong.

[sdmustangrider]

Originally Posted by bartl

Let me guess. You're connecting one lead of the voltmeter to the battery negative post and probing the harness with the other lead? If you do this you're using your meter as the ground wire. If you're NOT connecting the meter this way, please tell us how you ARE connecting it, because it's also wrong.

No. I'm grounding the meter to the chassis and testing the harness. We did that before I switched the harness and it was reading 12 volts. Now it reads 0. This is with the harness unplugged. When we tested the old harness unplugged before, it read 12 volts for the one wire.

[bartl]

So, if I understand you correctly, you were attaching the black lead of the meter to the chassis and probing the harness with the red lead, with the meter set to DC volts AND the ground cable disconnected at the battery and were reading a voltage other than zero?

I guess that POSSIBLE with a self-powered meter, connected as it would be in series instead of parallel and reading a voltage DROP of 12V caused by resistance within the circuit.

If you're really checking for a current draw or drain the proper way would be to attach a load (test light works well) between the battery- post and the disconnected ground cable. If you have current draw the lamp will light, the brightness depending on the load. If no load, no light. Having the door open and the dome light activated will light the lamp. We'd typically tape or wedge the door jamb switches closed while we disconnected fuses and feeds until the offender was identified.

[KarlJay]

Try this, get a headlight and connect the headlight to the 12v source and see if the headlight comes on.

Point: what you seem to be finding is 12 volts, without a known source. What you don't know is how powerful the source is (amps).

My guess is that it's a capacitor or capacitor effect. A piece of alum foil will act as a capacitor, so it could be many things.

You don't need a headlight, it could be just a test lamp or anything that will USE the 12 volts.

It's simple to make a tester out of an old horn or buzzer. I have one that I use to test ground. Connect 2 wires to a buzzer or horn, connect 1 to 12+ and probe an area to see how good the ground is, or to test connectivity in a remote area (this is why better connectivity testers have a buzzer).

I bet you don't get any usable power from this non-battery source. It's most likely 'left over' voltage (capacitor effect) from something like a wire or something.

Once you do this test, you can hook up the battery, wait, remove battery, test again. If it comes back, then you can start disconnecting things (remove fuses) until you find the area giving you the problem.

Remember: Voltage alone does NOT tell you everything. You can have 12 volts to your headlights and they can still be dim, it's AMPS that's the issue.
Here's a link to someone making a capacitor from a water bottle, you can get the idea from this or chew alum foil and feel the effect

You Tube

You Tube

This might be a better video to see my point:

You Tube

You Tube

The point I'm trying to make is that something is STORING that 12volts, you just need to find out WHAT is storing it.

[sdmustangrider]

I'll try these tips out. Thanks guys. I'm definitely not an electrician. I'd rather try to find the source on my own before I think about towing it to my mechanics shop and gave him doing it. I feel though as if I'm getting really close. Thanks again for the tips.