Hey guys, I need some help with my 06 Expedition. Driving home, the battery light came on (red this time). Battery died. Replaced both alternator and battery, but it keeps draining. Checked fuses, found two blown, replaced those too. Now I’m seeing a P0622 code (alternator field circuit). I’m thinking there’s a wiring issue, but I’m stumped. Any chance anyone has a wiring diagram or knows all the ground locations? Starter feels loose, gonna tighten it up, but I’m really hoping I’m not missing something obvious here. Thoughts? Suggestions?
Have you checked the main ground on the frame near the firewall? That one’s a common culprit. Definitely make sure your starter’s tight—those loose ones can cause all kinds of trouble.
P0622? I had that code pop up once, it was a bad voltage regulator. Maybe check that too?
I also an issue with my ‘07, a little similar, that turned out to be a bad PCM. Had to bite the bullet and replace it. If it’s not a ground or fuse, you might be heading that way, buddy.
Try using a multimeter to check for any parasitic draws overnight, might be a bad radio fuse.
Also, double-check the alternator connections, especially the small ones. Sometimes it’s the little things, ya know?
Thanks, I didn’t think about the voltage regulator. I’ll give that a look. I hope it’s not the PCM like you said earlier, but I’ll be ready just in case.
Loose starter, OMG I had mine wiggle loose and gave me all kinds of grief. Tightened it up, cleaned the ground, and all was good. Might save you a PCM swap. Worth a try.
Ford Expedition grounding issues are legendary at this point I’d say check every connection twice. Once had a ground wire corroded near the rear axle… chased it for weeks.
@ExpeditionFanatic Yep, checked that ground by the firewall. Tightened it up. Didn’t fix the problem, but hey, at least that’s one more thing off the list, right? Lol
Bad radio fuse? Seriously? That’s so random. My PCM issues felt like a death sentence—your radio fuse story makes me feel like I got ripped off
Yeah man, Ford gremlins are wild. I couldn’t believe it either until I replaced it and the drain stopped. No big-ticket repairs for me that time. Hope your PCM didn’t set you back too much.
Cost me way more than I’d like to admit. Wish it was just a fuse. But at least it’s running now. Ford’s got a way of keeping us on our toes, right?