Last night battery light came on. Drove 40 miles home with lights on. Today, it started so I headed out. About 10 miles of battery light on, gauge fluctuating mildly either side of middle, gauge suddenly drops dramatically. I turn around and head back. After a mile or so there's a terrible growling under the hood, sounded like it could be an alternator bearing. Just as I pull over, the noise stops but entire dash goes black. Popped hood, alternator spinning quietly and not hot. I drove back and it started stumbling and surging as the battery died and it finally quit almost all the way back.

I have battery on charger now.

I assume the BCM is the regulator by feeding current back to the field? If so could the growling be the BCM feeding back a huge field and the rectifier bridge growing? And the BCM fuse blew because too much current to alternator field coils? But how do I tell if it is internal, external or BCM regulated?

Will it start with a charged battery with the BCM dead? I need it to run to get to the parts place. Which fuses do I need to check? Then, how do I check the alternator, wiring, BCM regulator to find original problem?

Thanks,
Mark

 

Ford does not have a BCM ( Body Control Module ). Closest thing for functions to the GM term BCM is the BSM/VSM ( Body / Vehicle Security Module ).

The PCM monitors the alternator voltage over the Module Communications Network from the sensing and switching circuit on the alternator

The power feeding back to the field is from the Black w/ Orange stripe wire which is just after the gray fusible links and before the brown fusible link.

What fuse blew ? ( you make a note of a fuse blowing, but not what fuse it is ).

Start with checking the Black w/ Orange stripe wire for power.

 

Since you have no truck info on your profile, it really helps if you tell what year, body, and engine you have.

 

Good point, I was still thinking of the last thread when I did the reply, so it could be useless info, then again what is new ??

 

Sorry, 2006 extended cab 4x4 5.4 automatic. And it has to be a F150!

 

Since then, I charged for 4.5 hours at 15amps, put it back in the truck, started right up, dash works again, back to only problem is the battery light and weak charging.

The BCM may or may not be the regulator for the alternator. I guess, on a guess, I'll replace the alternator.

Mark

 

like they said there is no BCM, and yes just replace the alternator

 

How do I verify the alternator instead of the regulator function? Pull off Black/Orange wire and jumper to 12V and check output? And is there a rebuild kit for the alternator?

Thanks again,
Mark

 

Best way is to have it checked.