i have a 93 cummins 250 turbo diesel. the charging system works but is intermittent. when i charge the battery it will charge for a while then cut out at some point while driving. found a couple wires to repair in the harness on the left fender. i've gone thru most of the connections and cables but haven't completely opened the harness.

 

easiest solution is to go with a old style regulater and by pass the computer, theres a how to in the stickies

 

The most common source of trouble is the wiring harness to the crank sensor. If the PCM does not see a signal from that sensor it will not power the field circuit in the alt (no RPM signal = engine not running as far as the PCM knows).

The most common problems with that harness are chafed wires where it comes around the front of the head and where it is clipped to the timing cover, and corrosion in the connector at the front of the head. Also make sure the sensor is tight and that the gap is around 0.050" - use a non-magnetic feeler for this.

A flaky crank sensor will also knock out OD if your truck is an auto, and the A/C compressor and cruise if yours still works and was so equipped. If this stuff still works while the truck isn't charging then suspect a bad connection at the ASD relay (front one of the three on the fender) or a bad relay. The A/C relay (back one of the three) is identical and can be swapped for troubleshooting.

 

I had the same problem for the last year. purchased a new crank sensor truck is running great.
Purchased sensor from.
Cummins Rocky Mountain (303)287-0201

Part number 3924432 speed sensor $60.21

Ordered it on a Monday it was delivered on Wednesday to my door.
Dodge dealer wanted $139.00
Good luck hope that this helps.

 

I had the wiring chaff at the front of the head like Dave said. You have to look close, there may only be a tiny pin hole.