Charging system not working!

[DStal]

Im a Newb,
1st post, Hi ya doing!
Ok the problem im having is the alternator isn't charging the battery. New Battery and alternator and Batt. cables. I checked the fuse box and alt slot isnt putting out any volts. Another thing i would like to know is can a bad fusible link still read 12v. Basically whats the best way to find problem. Been testing with my multi-meter like crazy.

[Chris Smith]

What do you know about all of the alternators? [types, ages]

The alternator in some cases needs a boost signal to get the field winding going on some of the older systems.

The diode trio will do this on the later ones and the battery lead needs to be in tact.

You should be able to produce voltage with out the major need of the rest of the car, battery, or harness if you know what your doing and you know the age / design of the equipment.

[Janitor Tzap]

The first thing you need is the wiring diagram for the vehicle.

{If your Vehicle isn't that new.}
You can goto your local library, and photocopy it.
Or go to one of the auto parts stores and get a "Hane's" manual on your vehicle.

Next.....
Once you have a Wiring diagram.
Trace the wiring from the charging system.
There maybe a Relay or Regulator that it goe's to, as well as a Fuse block
under the hood somewhere.
Check to see if any are bad.

I have see the problem where the regulator goes out, but is part of the MPU on some model GM Vehicles.
Which gets expensive to replace.

Good luck.


Signed: Janitor Tzap

[jollyrgr]

If there is an Auto Zone, Pep Boys, Advantage, or other national auto parts chain near you simply pull the alternator and have them bench test it. Auto Zone, Pep Boys, etc. usually will bench test these for free. Just because it is new does not mean the device is working.

If the alternator is fine there are a couple things to look for. Based on your signature I'm going to assume you are working on a GM vehicle and specifically a Chevy.

As Chris stated these types of alternators require a field signal to get them working. Unless you have a very old style alternator with an external regulator the regulator is built into the alternator on Delco (GM) devices. One of the failure points is the pigtail that connects to the side of the alternator. One of the two wires connects to the output of the alternator. This wire is only a inch or two and I've never seen it go anywhere but the output terminal of the alternator. If I recall correctly this is the "2" therminal. If this wire is not connected or there is a problem with conductivity the alternator WILL NOT WORK! If this is corroded or the spade connector is not crimped enough this will be a failure point. And yes, I have had this cause an alternator to not work.

The other of the two wires of the pigtail (the "1") goes to the alternator light on the dash. On some cars there is a wire wound resistor on this line as well or possibly an amp meter.