I have a 1996 F 250. It has the 7.3 PSD in it. I have had a battery light on for years. I read somewhere it could be the ignition switch going bad. I changed it and the battery light never went out. The truck charges fine and the batteries last for years.


Anybody have a clue as to what it could be?

 

Usually that means a failing diode in alternator. Will still charge just not as well. Doesn't explain batteries lasting so long tho.

 

I have changed the alt since it has been on. Even used a Ford alt for the replacement. Light has been on for 7-8 years.

 

All that light means is that there is a voltage difference between alternator output and battery voltage. I would measure alt output terminal to case ground and chassis ground as well. Compare this to voltage from battery + to chassis ground and since you have dual batteries do both of them.

 

Do you think it could be something as simple as a grounding issue?

 

most likely a bad little plug on the alternator. they get hot and start to melt.

 

I changed my alternator and my light would come on intermittently had alt check it was good, checked the white plug it was good, stripped back the harness and a po had changed the plug out in the past and connections were good. I re-wrapped the harness and then added a bigger ID and longer piece of convolution to the outside of it and taped it securely, light hasn't come on since. I believe the harness vibrates and causes a intermittent loss of connection. Hope this helps.

 

Hmmm.....


Seems like I changed or extended some of the alt wiring harness at some point. I will look all of that over and see if they need some solder and shrink wrap.