Battery Light & Alternator Problems (with resolution)
First, I wanted to say I just registered but have used this forum as a resource for a while now. I've been driving an F250 supercab gasser for the past couple of years, but wifey recently gave me permission to find a crew. The crew I ened up with was a 2003 with the 6.0.
I ran into a small problem with the truck. I searched the forum about this and saw it was a common problem, and I saw people changing out batteries and alternators, and most never reported that they actually had a fix. So I wanted to share what fixed mine.
My truck had a fresh rebuilt alternator when I got it. It was the 'ToughOne' brand from Advance, their part # P8515. The day after I bought the truck, after putting less than 50 miles on it, the battery light started flickering randomly. I made a quick test rig to plug a multimeter into the cig lighter and saw voltage fluctuating from 14V down to 12V at random times, and the battery light would come in with the fluctuation.
Looking up schematics on AllData, I saw that the battery light was controlled directly from the alternator.
So I went to Advance, and without the receipt, I bought a replacement reman alternator. I hung it at work and drove home. On the way to work the next morning, I started getting the battery light again. When I got to work, I touched the alternator and it was HOT, much hotter than the bracket it sits on.
No one local had a new alternator in stock, just remans. So I ordered a brand new Bosch 135 amp unit from Advance, part AL7606N. Their website quoted 7-10 days, but UPS dropped it off the next day.
Installed it and the truck started right up and I haven't seen the battery light since. I've been running it for 2 weeks.
I wanted to share my solution and a warning. Don't get a cheap *** reman. The new Bosch part was $200, but Advance had a $50 coupon off a $175 purchase, so net cost was $150. Pretty cheap and the job only gets done once, where on my truck is on its 3rd replacement alternator.