Today my check-engine light came on. I checked the important things--oil, temp, volts--and all are fine. This is on my '95, 2WD 2500 with automatic (ATS) trans. The light comes on after about 2 minutes of driving. Any ideas? 388,000 on the ODO.

 

Just a guess for fun: I'm going to say that the alternator brushes are just starting to fail, and for a minimal time span the voltage dropped below commanded voltage and set the fault. I realize it won't be the original alternator, this is just the one fault I saw on 12 valve trucks with any regularity.

 

Interesting idea. I can check the voltage tomorrow.
It came on 3 times today, during 3 trips and didn't shut off till I shut the engine off.

 

Key on trick and see what the code is?

I can honestly say I have never seen the CE light on on any of my Cummins trucks...... It would probably scare me to death if it ever came on.

 

I tried turning the key on and off 3 times and then 4 times but I couldn't see anything. How exactly do you do it?

 

Bingo... I think. This morning the volt meter is showing what looks like about 12 volts instead of 14.5

The alternator is an O'Reilly's "lifetime" alternator. This is the last O'Reilly's "lifetime" product I'll buy. I put two of their "lifetime" starters in my truck--they lasted 3 years each.

Luckily I had the foresight to have my original alternator, that lasted 17 years rebuilt by a local good shop at the time I put the O'Reilly's crap alternator on.

 

That could be it, I had a code 41 or something like that low field voltage on my Ramcharger when I was having issues, but on both of my 97's, when the Alt took a dump no check engine light but a Batt light....... Go figure.

 

That was it. By the way, the Service Manual calls it a generator. So I put my rebuilt Denso generator on and the light went out and the system is charging again. Woohoo!! I looked the O'Reilly's generator over and it appears to be Chinese. No Denso markings on it at all.

Thanks guys.

 

Something else that told me it was the generator. For the last 3 days, the a.m. radio has had an odd sound that increased and decreased with engine speed. It was a buzzing/burping sound. Now that the rebuilt Denso is in it has disappeared.