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12 volt arc

C

cwhubb

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ok, there's a full 12 volt arc happening when I touch the neg cable to the battery, I couldn't find the cause so I took it to my mechanic and it's driving them nuts too. It doesn't happen when the ammeter is by passed, They use an independent source for the juice, as a matter of fact the car starts and runs great when it's by passed, I should mention the instrument cluster is removed. My mechanic said there's something that's drawing 12 volts right right off the bat, He checked the obvious grounds and all the electrical accessories that draw 12 volts, couldn't find anything wrong there but he said there's still a short somewhere. Have any of you had this problem? any suggestions?
 
From what you are describing, why not just leave the ammeter bypassed? It's a potential source of meltdown anyhow. Secondly, try popping one fuse at a time to see if that helps, but I would think a short to ground should blow a fuse.

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From what you are describing, why not just leave the ammeter bypassed? It's a potential source of meltdown anyhow. Secondly, try popping one fuse at a time to see if that helps, but I would think a short to ground should blow a fuse. Also, everything is at 12VDC potential, they draw current when operating.

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From what you are describing, why not just leave the ammeter bypassed? It's a potential source of meltdown anyhow. Secondly, try popping one fuse at a time to see if that helps, but I would think a short to ground should blow a fuse. Also, everything is at 12VDC potential, they draw current when operating.

Do you have access to a digital voltmeter DVM which measures amperage?
 
You say your cluster is out, the only hot wire going into the car is the red wire that goes to the ammeter, are you sure that's not touching ground?
 
yes, thats the only way it starts is with the ammeter bypassed, and it's not grounding out

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my mechanic has all the meters
 
remove one fuse at a time until it stops when it stops that is the source of your problem if it persists you must continue to isolate could be a bad alternator no fuse for that disconnect it see if it stops if not continue to the starter circuit something is causing the draw if you had a hot lead touching ground you would not have a car left left it would start a fire you should really measure the amount of draw with an amp gauge by the way if you bypass the ammeter car will not charge
 
It sounds like a parasitic drain then, not a full short. Your mechanic should be able to set the DVM to read amps, then connect in series between the battery and the car (red or black wire). Secure all wires carefully! My Fluke for example can be used at 10A or 40mA. Start at 10 and see what it draws WITH IGNITION OFF. Do not leave the meter in series when you crank it. This is just to determine parasitic drain with engine off.
 
Hang on, the only way it starts is with the amp meter disconnected and what the red and black tied together? I would figure out what that is the problem then go from there. If everything is stock and is installed properly it should work fine, you should still bypass the amp meter eventually but starting off with an issue then describing another issue from that point is not the best way to troubleshoot.

99.9% of had arching on battery posts are due to a short, a positive line somewhere is shorted out, probably already blown the fuse or is tapped right off of battery power with no fuse, good grief who knows what you have rigged up trying to put power on a system with the cluster out is asking for trouble lol
 
If it does it only when the ammeter is connected, it sure looks like the ammeter is the issue. What does the ammeter needle do when connected?
 
I'll have to ask my guy, I know all my gauges spiked that's why I took the cluster out in the first place. I have a back that likes to go out so so I couldn't bend enough to replace the regulator with the electronic one.
 
you have a parasitic draw issue. The causes that come to mind are dome lights, improperly connected stereo / amp (they are supposed to be switched off when not in use), clock. Happen to have an MSD ignition? they are supposed to switch off when not in use with an internal relay, but many also draw a small current even when off.

What I did to find my issue - with both battery terminals connected, start at the + battery terminal and measure the current draw with a clamp-style ammeter. As said above, while you watch the clamp style ammeter, have someone remove each fuse one by one. You should notice the amp draw either going to zero (one circuit is the issue), or reducing but still being present (indicating you have more than one issue). Then, once you've isolated the circuit, follow each lead until you find which lead(s) are the culprit.

Remember, not every short to ground is a perfect short. The short could have a bad connection due to painted surface, oxidized 40 year old copper, or wire sheath that is still somewhat intact.

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Hey, I was looking through your posts to figure out what type of car it is and I found you posted about something similar over a year ago. Same problem or different? What was the cause?

http://www.forbbodiesonly.com/moparforum/showthread.php?75464-neg-battery-post-sparking
 
same stinking problem, I was trying to fix it myself but i gave up. It doesnt have msd
 
If it was mine, first I'd go for the obvious...

Look over any, and all wires near your exhaust manifolds and pipes for burned wires. What your probably looking for will be fairly hard to find...a real pain. Most likely a pinched hot wire, or a hot burned against a ground.

You probably need to start isolating each different circuit, even to get an idea where to look. Pull the wire plugs out of the firewall block, and see if the battery sparks then. If no, that tells you the problem is aft of the firewall. Then try plugging only one harness plug into the firewall block, and see what happens. Try only one at a time. It could show you at least where in the wiring the grounded, or problem wire is.

Just keep tracking things down, you might find it.
 
Not to sound like a broken record but always check your grounds first, ALL grounds. Get that out of the way. I checked the previous posts and didn't see it but it would help if you stated the year & model of your car. Also, depending on the year & model, there are certain components that are connected directly to the battery, so they need to be eliminated too. Some models have 2 wires directly off the battery (to ammeter & starter solenoid) and some have 3 (to ammeter, starter solenoid & horn relay).
 
there's a headlight delay switch? relay? the manual calls it a delay it's on the headlight circuit, what is it and what does it do?
 
It keeps your headlights on for a period of time after you turn the ignition switch to off
 
thats what I thought. did all the 70 chargers come with that plug already wired into the harness and then only used when the delay option was ordered? if it's not used is it a plastic plugin connector at the end of the wires?

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I'm thinking some one may have disconnected it at one time did a hack job and its shorting out
 
update, My mechanic started from scratch again and took the whole cluster apart and is almost certain the problem is the ammeter. I had taken it apart a few times looking for burnt or indications of an arc never noticed one but the mechanic saw a small spot. he thinks there should be a current isolater or insulators, cant remember what he said, that keep the ammeter studs from contacting a ground, he found some info that suggests they were triangular shaped. I do remember reading that replacing the false nuts on the gauges make a better ground and so I did exactly that, Did I screw the pooch on that one?
would those cap nuts with the nylon inserts work?
 
Probably I did that once ruined the meter tossed it put in a new one un hooked up and use a voltmeter now lol
 
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