alternator check

[phmezz]

I'm trying to isolate an E4OD O/D flashing light problem. The first thing I did was check the alternator. I get 14.6 volts from the driver side battery and 12.55 volts from the passenger side battery. Is this normal? Shouldn't I be getting about the same voltage from both batteries? I get 12.55 from both when the engine is off. This is my first diesel so my first vehicle with two batteries. I'm going to hook up my code reader next but thought this was odd when I did the alternator check.

1993 F 250 7.3l IDI

 

[chris142]

Ya they should be the same voltage. Prolly got a bad cable

 

[phmezz]

Check it again. Getting 12.55 on the battery post and 14.6 on the cable. Will try cleaning it up then put on a new cable of needed. Thanks.

 

[icanfixall]

This battery voltage difference is telling you the connections or the cables are bad. Try cleaning them because they should both read the same voltage. This voltage difference will not cause the trans issues.

 

[phmezz]

Cleaned my battery cable connection. No change. Guess I have to buy a new cable. Oreilly has one for $83. Cheaper than the other auto parts places and cheaper than ebay. Wow, that's a lot for a battery cable!

 

[lindstromjd]

Um... a flashing O/D light has NOTHING to do with your alternator. It's a transmission trouble code, like a CEL for your engine. Time to get the code checked before you destroy your transmission.

 

[phmezz]

Yep, I pulled the code (62). I've got another post about it. Separate issues. Looks like a TC problem.