1997 Isuzu Rodeo 92,000 miles 3.2L V6 Auto.
No output from alternator. Replaced alternator, still no output. In troubleshooting wiring I disconnected the red/white wire at the harness that goes to the generator gain control (in the ECU?). Alternator charges when wire is disconnected, will not charge if wire is connected. No voltage @ this wire KOEO or KOER. Should be 10.5v KOEO and Bat voltage KOER?
Short to ground inside ECU @ generator gain control? Must replace ECU to fix?
OK-It's fixed. Turns out both of the NAPA reman alternators were bad. The internal regulators were not wired properly. The ISUZU alternator's gain control needs a 12v signal from the regulator or it will ground the regulator out. The NAPA alternators were not putting out any voltage through the red/white gain control wire. We installed a Carquest reman alternator and got the voltage signal we were looking for, the ECU was happy and the alternator was allowed to do it's job.
This was after 10 hours of diagnostic work! : Evil: