Hey guys,
I have a 2005 Ex, 6.8L V10. Purchased it this summer, ~95k miles. I've had the engine fail to turn over twice just recently. It jumped very easily, so I assumed it was the battery (esp considering the battery was seven years old). I replaced the battery and it promptly died two days later.

Yesterday, I replaced the alternator with a Duralast gold new alternator. Everything went just fine, esp considering it was my first time replacing an alternator. Electrical system checked out after the install - 14.5V at battery with engine one, 13.5V with all systems going crazy @ idle.

I trickle charged the battery overnight and got in this AM. Noticed that the battery light was on. Hmm. Checked voltage of battery. 13.1V engine off, 14.5V at idle. Drove son to preschool. No issues. Came home. Stopped and restarted engine. Light is still on. Same voltages.

Read my excursion manual and checked the ground from the negative post of the battery to the chassis. Not loose. Checked post cables - not loose. Checked connections at alternator - not loose.

Any ideas, oh great and wise FTE Excursion gurus?

Thanks in advance,
Tom

 

When I was chasing down close to the same issue, it was the voltage regulator pigtail that plugs into the alternator. I ended up replacing everything else and still had the issue and then replace the batteries, alternator again along with the plug.

I figured out it was the plug by having the truck idle and my wife watch the battery light to let me know if it turned off while I wiggled the wires and the plug around.

 

Hi,
My 2005 6.8 does the same exact thing. Where did you get the pigtail? It doesn't look like Rock Auto has it.