More 1996 C3500 starting/electrical problems

My '96 C3500 crewcab dually has given me fits over the past week. It has around 37K on it and began to have problems starting this past summer. I checked the batteries and starter/solenoid and replaced all. It ran fine until November 2003 when it was as dead as a doornail. :screwy:

After recharging both batteries (tow package), it started fine. But now it cuts out very abruptly and without any warning (restarts and runs fine). The alternator and charging system test out OK. It's clear some electrical gremlins are at work here! Can anybody give me a clue as to what else to look for? :eek7:

I assume you have a big block, if so check the wiring harness that runs over the top of the egr pipe, I have seen some burn the wiring and cause weird concerns.

99ssconv- Thanks for your reply. Yes, you're correct that it has a 454
and I've checked the harness over the EGr and found no problems. While both batteries have passed a load test, I found one that had a corroded terminal. After cleaning it, the system seemed weak even after external charging. Decto go ahead and just replace the suspect battery and now the truck seems to start and run fine.

LESSON: Always, always look for the most obvious faults first!