Alternator help

[hudlow]

Did this problem just show up? Did it always do this? Was any wiring changed or messed with prior to this problem?

Since you said the problem goes away when disconnecting the small wire from the alternator it sounds to me like the alternator is being energized by the voltage regulator (field/excite wire) or a diode is blown (did you try an AC ripple voltage test like I posted below...what was your reading?)

What year is the vehicle? Does the voltage regulator look like any in these photos: link? It could be that the key-switch wire which turns the voltage regulator on could have constant 12v on it instead of 12v with the key-on-only. If you have 4 wires on the voltage regulator: one should go to the alternator (that small wire), one should be a voltage sense wire (goes to a battery terminal or post), one should be ground and the last should be the "turn-on" wire from the key-switch. If you can figure out which is the last wire then see if it has constant 12v with the key-switch off. Or it may be reversed with the voltage sense wire. If you could take a photo of the voltage regulator and wiring that may help.

I "inherited" this 1974 Jeep truck and its electrical problems. I don't know the history very well as far as the wiring goes. I suspect it had been worked on since there was a spare alternator and regulator in the toolbox of the truck when I got it. I have been told it has a "Motorola" or Ford type alternator/voltage regulator setup. The regulator appears to be some sort of solid state device, I'm almost 100% sure it has four wires.

On the back of the alternator are several terminals that all gave a ~12VDC reading when the truck was running. I attached both the wires to the same terminal.


If it's any help here are the components I have replaced on this truck.

http://www.autozone.com/R,APP184674/vehicleId,1381301/initialAction,partProductDetail/store,443/partType,00086/shopping/partProductDetail.htm

http://www.autozone.com/R,APP203675/vehicleId,1381301/initialAction,partProductDetail/store,443/partType,00097/shopping/partProductDetail.htm

Thank-you for your time and patience. The way my schedule is now I won't be able to work on this truck until next weekend to give you any progress reports.

I do thank-you for all your help.

I'll get something up ASAP.

hud