Charge light came on

[scrmn6guns]

Hello Diesel Guru’s

The other day I started my rig, the one listed in my signature, and the charge light stayed on after start-up. I was already out and needed to drive it home so off I went. I turned off any additional electrical components (ie, stereo, heater blowers, etc.) and started off. Once the engine RPM’s came up to about 1500-1800 the light went off and stayed off until I came to my first stop sign/light, then it came back on. It went off again as soon as the RPM’s came up. This continued until I got home. Once there, the light stayed off even at an idle. So with that in mind, I have two relatively new batteries, both less then a year old. Do you think alternator? Or after reading on here, I’m also think diodes. What is your input??

Thanks in advance
Jim

[woodnthings8]

More than likely the alternator is going. More than likely the brushes are worn to the point that the wire connecting them is holding them off the armature. When the engine rev's the alternator makes more power and that is enough to turn off the light. You can get a new unit or if you can find brushes they can be changed if you have a little electrical experience.

[scrmn6guns]

Thx... I have an alternator shop by me that I've used in the past, I'll give them a call and see what they say....

[Skydiver]

Sounds like what happened when my alternator was going out. I went to a Schucks auto place and they came out to my truck and tested the alternator while the truck was running. Bought an alternator there, put it in, and no more problems.