Sab

I got this car with the alternator missing. no history as to what happened.
Looks like car grounded out and alternator broke off.
got a new (rebuild) alternator and it is installed.

apparently no charge.

what can I troubleshoot?

how can I test if my new alternator is DOA or if maybe some of the cabling got damaged due to the aparent impact?

could not find anything relating to alernaor wiring or troubleshooting in the manual. But found one large and one small wire and hooked it up to large and small connector.

Alan

Take off the small Alternator wire - when you turn on the ignition do you get 12+ volts on that wire? This is the exciter wire from the dash pod - its fed via the charge bulb in the dash.

Test with ohmmeter the connection between the jump post & the alternator main connection - good conection? jump post and starter main terminal - good connection?

Also check connection between alternator body metal & ground. Does the new alternator have a dedicated ground connection?

When you turn the ignition on - do you get all the dash lights?

Does the car start and run on the battery alone?

Alan

Sab

Thanks Alan,
car starts and runs normally on battery.
I don't think I do get a battery warning light in the dash at all.

I will follow your troubleshooting tips and post results.

Garth S

If you follow Alans good sequence to no avail, then ....
The best test for an alternator is to take it to a rebuild shop, etc where it can be load tested: they are mounted and spun with an ~5HP motor and the output fed into a large battery bank .... the objective of which is to get design amperage at spec voltage ..... ~100 amps @ 14.5v.

Alan

Try grounding the small alternator wire while you turn the ignition on - does the charge light illuminate then - if not there is a problem with that circuit. If this is the problem - given the alternator was ripped off with that still bolted on I'd look for a break somewhere near the alternator....

Alan

Sab

OK, the charge light never comes on. I grounded the exciter wire, no change. But I can't seem to find an obvious brake in the wire.
Where does that wire go? Could I bypass it to test?

RicerSchnitzzle

Technically you can run a small wire form any keyed source with a 85ohm resister. I gave up on the membrane backing to my gauge pod and ran a jumper from the fuse panel incorprating an 85ohm resister in line. Works like a charm.

The break could be in the wire itself or the gauge membrane or even dirty connectors at the gauge membrane wire harness clips.

85fortheDrive

As someone dealing with alternator issues as well, I have learned just a little. My understanding is that "rebuilt" alternators are not the same as "remanufactured" alternators. The latter represents a more comprehensive overhaul of the unit.

I'm assuming that with NO alternator whatsoever, you now have a remanufactured unit. But if you do mean rebuilt, then I would be more skeptical of the alternator.

Don't mean to split hairs here, but I learned that distinction today.

Sab

Sounds like a plan, I will fetch an 85 Ohm resistor at Radio Shack and give it a shot.

Alan

You should get a 2W resistor so it doesn't burn up - a 1/4 W type will not do the trick.

It could be as simple as needing to change the bulb in the pod.

Alan

Sab

Hi Alan,
so the 2w should work?
I just want to make sure the alternator works. once that is verified, I can still dive into the dash and replace the bulb...

Alan

Yes it should work.

Sab

all I found was either a 10W 100 Ohm or 1 Watt 10 Ohm resistor.
I guess the 100 Ohm 10 watt should work, no?

85fortheDrive

Alan - as you know I have a similar set of electrical gremlins going on with our 84 5spd. Tonight, I tested this and found the following"

With no key in the ignition - 12.6V between exciter cable and alternator housing
With key turned to 2nd spot, just prior to starting the engine - 0.75V between cable and housing.

Also, when key is turned to second spot, the emergency brake (!) light and the light at the bottom of the oil pressure gauge both are flashing.

Sab, I don't mean to hijack this thread, but didn't want to start a separate one so closely related.

Sab

Great, I wired from alternator to the fuse panel with the 100 ohm 2w resistor and it is charging now. thanks for all the help.
I will take the pod off and see if I can make it work how it supposed to.
There is no battery light and no movement on the voltage meter. are these two items interconnected?

84tothefloor,
I have the same flashing ! and oil pressure warning before start. But I do not know if that is normal. I guess it is.