electrical issue

[mcmopar]

Hey guys, I'm no automotive electrician so I'm going to run this by you. when I went to Old Town this past Saturday I noticed a problem - well 2 - with the runner.
1st - It was charging wildly on the way there. I just attributed this to the fact that it has not been driven in about 2 months. On the way back the needle in the amp guage started to back off so I think my suspicions are correct on this.
2nd - when I shut the car off and turn the key over to the auxilliary position in order to power the stereo the needle on the amp guage swings HARD to the discharge position and I hear an audible sound as it does so. Its just a quick noise that is not sustained. I'm wondering if the ignition switch, starter relay or something else has gone bad. What do you all think?

 

[Big John]

I'll bet it's the ammeter itself. The noise might be the needle hitting the stop when it shows discharge. The other thing that comes to mind is some sort of huge electrical draw (like a dead short) in system somewhere.

If it was just charging, then I would suspect a regulator, battery or possibly even a battery cable.

 

[Big John]

Check output voltage when the engine is running at the battery and inside the car someplace like the cigar lighter. Check it again with your stereo on and then repeat those voltage checks with the engine off.

 

[george68hemirr]

mine did the same thing and it toasted....by pass it and install a volt meter gauge

 

[SomeCarGuy]

Take one wire off the back of that junky amp meter and just put it on the other stud.

Add volt gauge

Run shunt in 8 gauge wire from back of alt to stater relay. 12 guage fusible link.

Or go all out and drill out the bulkhead and run new wire all over.

The VR needs to be grounded, right? Can't remember for sure. Maybe needs mounting area cleaned up or a dedicated ground wire ran to the case.

 

[moparstuart]

which style voltage regulator are you running ?

 

[A31PKG]

It sounds simple enough, but the amp gauge simply displays the flow of current either to the battery - charge - or from the battery - discharge... Basically, it reacts to the magnetic field created by electron flow. From your description, it sounds like it's working. When using the accy position you should see the needle move to discharge because current is now flowing opposite what it would normally with the engine running & the alternator in the circuit...

The slamming of the needle to discharge could be a faulty gauge or a very significant draw (maybe even short) somewhere... With everything off (lights, radio, etc) and the key in the accy position, you should see little if any needle movement... if you do, then there is definitely something amiss... I would start by pulling fuses one by one until the needle returns to the middle... At that point you've found the circuit with the high draw... If the fuses don't reveal the culprit, then you could have a shorted diode in the alternator?

Keep us posted

Edit: In fact, with everything off, the key switched to accy, and if there is an excessive discharge reading on the gauge, try dissconnecting the 12v charge wire on the back of the alternator...that would help rule out a short in the alternator.