Brothers truck, 2001.

Alternator quit charging, shut everything off and drove for an 1hr and got to town and put on a new alternator, only one they have that is identical replacement. New alt is putting out 12v on gauge, start driving and gauge falls to 8. He is going back to parts store to get batteries tested they are 2 yrs old and probably new alt.

Is there anything else that would pull the volts down when driving? Its dark now so he may be stuck for the night.


Update:

Batteries tested good and were taking a charge so he left and got back on the road. 10 miles later truck dies. He never tested new alt . He is south of Sterling, Colorado on I-76.

2nd update:
Brother got towed back to Sterling. Going to get new alt checked in the morning which i told him to do before he left Sterling.

 

pcm issue maybe did you checl all the fuses and relays

 

When I get to work I am going to check Alldata to see which fuses and relays may be at fault just incase the new alt tests good. Hopefully it's not the pcm.

 

Mine shows a little over 14 volts with the engine running.

 

Update 3:

Verified new alternator is good. His truck is parked at a dealership so he is going to have them check to see if the PCM is ok. Not sure what else to do. Is there anything in the PDC- relays that would cause a no or low charge situation. I've looked at the PDC diagram on Alldata but didn't see anything related to charging.

Stumped!

 

Update 4:

140 amp fuse blown, None in stock. 120 amp is available but I dont think it will last.

 

Fixed!

Service Mgr had mechanic pull a 140 amp fuse from a 99 the dealership owned so my brother could be on his way.