Hey guys, have 1999 F-350 SuperDuty, 7.3 Diesel. Looked at a post from 2010, which had truck just shut off and wasn't sure if he was saying it would turn over but not start. It was suggested it might be CPS. Mine stopped, no electrical at all. Waited a few minutes then it started right up. Alternator light on, but cleared out in 20 seconds. Checked batteries and alternator, parts store said all three were bad. Replaced batteries under warranty, rechecked alternator, shows good. No check engine lights, but I did notice that as the alternator was being checked, different light s went on intermittently, and the speedometer was jumping between 0-10 mph while sitting. This shutdown happened three or four times. Any thoughts?

 

Loose/bad ground wire maybe? Bad battery cables possibly, but more likely ground issue.

 

You cannot trust the parts store handheld battery/alternator tester. The bench testers inside the stores are also not very accurate. Battery CEL is on but goes off when rpms increase sounds like a bad alternator to me.

Save yourself the aggrevation and by OEM if the budget ok's it.

-- Dave

 

Would a bad ground on batteries cause a complete electrical shutdown? It doesn't seem like batteries should affect anything after the vehicle is running. And wouldn't a bad alternator show up on gauges, or lights or codes? This issue shut down everything electric., One battery still had a good charge on it. If the alternator was bad, wouldn't battery kick in and keep it running? If battery was bad, would it restart strongly and just run on the alternator?

 

Tony, bad batteries will create all kinds of electrical gremlins! You haven’t mentioned taking a multimeter to your (disconnected) batteries or to your alternator. These are simple things YOU can do to eliminate or confirm that your batteries and alternator are good or bad. Bad batteries can kill your alternator and a bad alternator can kill your batteries...