Hi All,

I'm having a strange electrical problem. My van is a 1994 B250 with a 6 cylinder. The voltage gage is moving around and I get the check engine lite with a code of 41. That means a low voltage condition (< 11.75v) has occurred. The alternator was checked and it is ok. I cleaned all the contacts on the alternator. I also replaced the drivebelt tensioner and still have the same problem.

The voltage gage starts out at 15 volts, but then as I drive, it starts fluctuating untill it is below the 11.75 volt threshold and the check engine lite turns on. Anyone have any clues as to what I should check next?

I started to suspect an overheating alternator, but the van was in a parking lot all day in 40 degree weather, yesterday. I started the van and it showed a low voltage on the charging gage.

Thanks in advance
Steve

 

Well, it turned out to be the alternator all along. I took the alternator to a rebuilding shop. The shop rebuilt the alternator in about 4 hours and charged me $90, which was cheaper than buying a new one from AutoZone.

I got a false positive from the AutoZone tester, probably because they only go up to 300RPM and the alternator shop can put a much larger load on the alternator.

So, the van is running again...