My battery was draining – I ruled out the alternator as the possible cause. What I found was two wires coming off the alternator one going to the battery the other to the dashboard. The one going to the dash is not giving off a charge. Does anyone know where this wire leads? I think there might be a short somewhere. Did anyone ever have a similar problem?
Thanks

 

The alternator has 2 wires, OK you know that.

One is a heavy 12v "hot" direct to the battery, well almost, not switched is what I mean.

The smaller wire, is the ignition feed TO the exciter circuit of the alternator, and is DEAD with ignition OFF.

With the alternator OUT of the cicuit, battery wire disconnected and insulated, you dont want sparks, and the drain is gone, it is possibly the voltage regulator, or a diode inside the alternator is leaking to eartrh, it does happen.

 

The wire that goes to the ignition, that does not have a spark with the ignition on. Does that mean there is a short in the wire or is it another problem I should look in to?

 

The wire that goes to the ignition, that does not have a spark with the ignition on. Does that mean there is a short in the wire or is it another problem I should look in to?

 

The small wire coming from the alternator...the "excitor" wire.....will not have voltage simply with the key on.

The exciter wire goes to one side of the warning light bulb in the dash. The other side of the bulb has 12v whenever the key is "on". Until the alternator starts charging, the exciter wire is "-"....and that's why the warning light comes on: positive on one side of the bulb, negative on the other.

When the alternator starts charging the excitier wire goes "+". With "+" on both sides of the bulb, the warning light goes out.

So...does your warning light work?

Cheers
DD

 

To test the small wire, disconnect it from the alternator, and connect it to ground with a jumper wire or just hold it against bare metal nearby (or best of all, the negative post of battery). With the key on and the small wire grounded, the battery light should be on. If not, there is a problem somewhere on this circuit.