After picking up my 2002 F-150 Supercrew from the shop after they finished brake work, I was driving it home (it was nice to not have the ABS light on), the battery light was on. Since it was the weekend, I called the shop on Monday and told them the light was on. The service guy said that they noticed the light was going off and on. I asked them why didn't they check it out? Well, that's a whole other issue that I won't get into right now.

I took it back, they did a diagnosis and told me I needed a new alternator. Since I've already replaced the alternator back in 2011, I told them I would do it.

I received a new alternator (the one I put in in 2011 has a lifetime warranty) and installed it today. Since I've heard that a defective belt tensioner can also cause charging issues, I replaced it, the idler pulley and the serpentine belt. I cleaned up all the harness connections, both at the alternator and the firewall. Still have the battery light on.

I'm thinking the battery is being overcharged. A multimeter reading at the battery with the engine running is 14.55 volts. A reading with the battery at rest (taken about 2 minutes after shutting the engine off) is about 12.8 volts.

I was wondering if a loose connection at the stator plug...




...might cause the issue and causing the light to come on? It seems to have trouble seating at the alternator.

 

Can you get a good scanner on it? Would be a lot easier than guessing