ok ive been working on my charging system alt is good but i am only getting 10 volts out of alt when i un plug altenator wires and the truck acts no diff any help please

 

Bad alternator. I'm guessing.

---AutoMerged DoublePost---

How's the regulator? Need a new one? There is a A C Delco one available one from O'Reilly's Auto for the 1991 Vin C trucks. Its like $50, better one than the house or BWD one IMO.

 

First off, your alternator is regulated by the PCM.
Question, are there any other things going on, like OD not working, tachometer not working?
IF so, then the troubleshooting should go to PCM startup, likely a sensor like the CPS.

If not, then check the fielding on the alternator. If you look at the back of the alternator, there,s a large stud, and 2 small ones. Now, with a test light:

1. Large screw bright (battery). If not, then the fusible link between the alternator and the battery is bad.
2. One of the 2 small studs should be bright, and the other blinking/flashing.

a. Both dark. PCM, or ASD problem, no field voltage available.
b. both bright PCM , or wiring to same. No field input from PCM.
c. one bright, one dark. Alternator is bad. (being fielded, no output)
The quickest and least expensive path to a repair is proper diagnostics.

hope it helps

 

Here is a link to a rebuilt PCM.

DODGE RAM TRUCK Cummins Diesel Computer ECM ECU PCM | eBay

Or you could bypass the computer and regulate with just the alternator and 12 volt regulator. HERE!

http://www.cumminsforum.com/forum/94...w-89-02-a.html

http://www.dieseltruckresource.com/f...n&onlynewfaq=1

 

make sure you have a good ground and that your voltage regulator isn't shot.

 

in reply to j martin every thing else works no other problems besides it not charging ive went thourgh every thing but on the fusible links you can unplug them but no fuses cant figure it out