So, we had to get our 2009 F250SD 6.4L Lariat towed last night. I wasn't there when it died but the symptoms were:

1. Wouldn't start (clicking from starter)
2. Light smoke from passenger side of engine bay (electrical smell was still present when I got there an hour later)
3. Even with key off the batteries completely drained in less than an hour.
4. Tow truck guy hooked up jumper cable and the truck powered up enough to shift it to Neutral for tow.

I am charging the batteries now from an external charger with the alternator disconnected (I traced the alternator cable from the alternate to the back secondary connector on the passenger side battery...is this correct?).

I suspect alternator based on other forum posts and the fact that I can't see how a starter short would *continually* drain the battery without the starter relay engaged. But I don't think I can rule out starter yet and don't want to waste time or money until I know for sure.

I did try to use my code reader with key in "power on" position but the display goes crazy with "Brake System Fault", all the lights flickering and even the speedometer going wild. Not sure if that is the just the batteries not charged enough (shouldn't the batteries be able to make the truck appear "normal" with the alternator disconnected?) or, God forbid, the ECU is fried or something. I'd like to at least get it to the point where i can get it to *try* to start...then if the starter sounds normal, I know it is the alternator for sure.

Ugg...sometimes I miss old cars where electronic crap didn't go to everything...Any help or advice appreciated.

 

You may have a battery that is internally shorted .

 

Thx, JWC...I hadn't considered that...but I am hopeful that isn't the case based on current observations:

1. After charging the batteries for about 5 hours, I turned it on...no flickering....good sign.
2. With alternator disconnected and external charger still attached to battery and in "engine start" mode, vehicle cranked and ran like normal. Battery light came on after about 10 seconds.

I believe this proves the alternator is the issue. Pls chime in if you think I've missed something.

Wow...lots of re-manufactured Alternators out there...any good brands? Ones to avoid?

 

Pull the alt. and have it tested . For piece of mind have your batteries checked also . You likely nailed it . Let us know the outcome . Best of luck !

 

Yep...alternator bad. Tested at O-Reilly's. Will be getting a new one tomorrow. Belt tensioner was a bugger...Bought a belt tensioner tool...but couldn't get it to fit...ended up using a socket wrench and some line and tied it off. Whatever works!

 

Alternator replaced. Trucking running. WooHoo! Upgraded to the 200A version...cost $460...Ug.

 

Glad you got it sorted . Thanks for posting your fix !