getrdun

Alternator gauge shows low voltage,and the dash has a CHECK GAUGES light flashing for the first couple minutes, now slow starting, should I just replace the alternator, or look for something else? put brand new batteries in a few months ago.

infidel

It's probably the alternator but have it tested first.
The PCM controls charge on these trucks and is known to go out and cause the same problem.

getrdun

Thanks for the reply, if it was the pcm would there be any other signs to look for?

huntman509

does the tach work? crank sensor could be out

getrdun

Tach still works

infidel

It seems like the PCM voltage regulation portion is likely to be the only function to fail most times.
Get the alternator tested, most autoparts do it for free.
If it turns out the PCM regulator is bad not to worry, you can add an external regulator without replacing the PCM for under $25.
Instructions> https://www.dieseltruckresource.com/...n&onlynewfaq=1
Instructions are for 1st gens but work on all.