[FIXED] 2011 ford escape 4 cylinder charging system issues

doing work on a body shop car that was struck by lightning. ran very poorly. the vref as ford calls it was 2.2 volts. code was p0642 if anybody wanted to know. found the app sensor was pulling down the reference voltage. unplugged it came back, so we have one of those on order. according to ford the only things on that circuit are the app, fuel tank pressure sensor, ac pressure transducer, map. so it runs now not throttle response (which is to be expected) charge indicator is on battery isnt charging. i checked for power at the big cable. the little brown and red wire. used a scope do not see any control on the gen com wire, or any square wave on the gen mon either. checked the gen mon wire and com wire with a headlight to rule out high resistance. and checked for short to grounds/power none found. any other checks before calling a bad pcm?? code is a p0620 for the charging system

What are the voltage levels on the GENCOM and GENMON wires? I'd expect 0V on COM and around 10V on MON, even with no square wave activity. Mostly just trying to tell if the alternator regulator is still halfway alive. Who knows after a lightning strike, right? :silly:

The only other thing I'd suggest is unplugging the alt field connector and getting the engine speed above 3K RPM. I know that'll be tough with the APP issue, but if you can get the alt to self excite, then it means you probably don't need one, and can go on with PCM replacement.

Fixed. unplugged alternator as you suggested charged at 13.5 volts. put pcm in it programmed it and all is good now.

Tyler wrote: What are the voltage levels on the GENCOM and GENMON wires? I'd expect 0V on COM and around 10V on MON, even with no square wave activity. Mostly just trying to tell if the alternator regulator is still halfway alive. Who knows after a lightning strike, right? :silly:

The only other thing I'd suggest is unplugging the alt field connector and getting the engine speed above 3K RPM. I know that'll be tough with the APP issue, but if you can get the alt to self excite, then it means you probably don't need one, and can go on with PCM replacement.

Tyler, can you explain the self excite circuit of that alternator for me? I remember doing a case study with a GENCOM and GENMON test, but I'm drawing a blank offhand.
Which one of those two is the computer telling the alternator what to do and which one is the feedback circuit? Thanks!

ScannerDanner wrote: Tyler, can you explain the self excite circuit of that alternator for me?

I'd love to! But, I honestly don't know how/why the regulator is wired this way. :blush: I just know that all the Ford PCM controlled alternators function this way, and even some of the internally regulated units.

Since the large B+ cable is the only electrical connection left after unplugging the regulator, I have to figure that the regulator is sourcing power from that cable, and somehow detecting an increase in rotor speed. Where's Andy when you need him? :lol:

Which one of those two is the computer telling the alternator what to do and which one is the feedback circuit? Thanks!

The GENCOM is the command to the regulator, with square wave pulses at least once every five seconds, or during load changes. The MON is the feedback, 0-10V duty cycle. I wanted to see if the MON circuit still had 10V, as that voltage comes from the PCM.

cheryl wrote: Fixed. unplugged alternator as you suggested charged at 13.5 volts. put pcm in it programmed it and all is good now.

Sweet! Any other surprises from the lightning damage?

Tyler
So Ford systems that are using the GENCOM and GENMON alternators. For a no charge event, unplug the alternator connector and hold over 3000. IF it starts to charge = alternator is fine, there is a control issue with the PCM or wiring in between.
Does that sound right?
Thanks buddy.

ScannerDanner wrote: Tyler
So Ford systems that are using the GENCOM and GENMON alternators. For a no charge event, unplug the alternator connector and hold over 3000. IF it starts to charge = alternator is fine, there is a control issue with the PCM or wiring in between.
Does that sound right?
Thanks buddy.

Yep, you got it. Of course, getting to the connector is easier on some than others - like a V6 Ford Escape.

You'll love the next step. The OE flow chart then recommends shorting GENCOM and GENMON together, starting the engine, and looking at the associated scan data PIDs to match. If they do, then the wiring is good, or so I'm told. :lol: I found this the other day while poking around Mitchell, just gotta get the Escape away from my wife so I can try it.

to answer your question the gen mon did have 12 volts unplugged. as for other surprises yea it doesnt have turn signals or headlights

Tyler wrote:

ScannerDanner wrote: Tyler
So Ford systems that are using the GENCOM and GENMON alternators. For a no charge event, unplug the alternator connector and hold over 3000. IF it starts to charge = alternator is fine, there is a control issue with the PCM or wiring in between.
Does that sound right?
Thanks buddy.

Yep, you got it. Of course, getting to the connector is easier on some than others - like a V6 Ford Escape.

You'll love the next step. The OE flow chart then recommends shorting GENCOM and GENMON together, starting the engine, and looking at the associated scan data PIDs to match. If they do, then the wiring is good, or so I'm told. :lol: I found this the other day while poking around Mitchell, just gotta get the Escape away from my wife so I can try it.

You know me well Tyler Thanks for the info.!
And nice job cheryl hartkorn!

cheryl hartkorn wrote: to answer your question the gen mon did have 12 volts unplugged. as for other surprises yea it doesnt have turn signals or headlights

Psh, headlights? Turn signals? Who needs 'em! :lol:

(Sounds like the BCM is cooked?)