My 2016 F150 XLT Ecoboost F10 Sport 4 WD presented me with a curious issue the other day... An error message appeared on the screen, as I pulled out of my driveway, that said "Check Locking Differential" and the truck stopped running and came to a rest... I managed to limp back to my driveway and there it sits...
I have inspected the wiring under the truck including the rear differential and the front differential housing around the actuator switch and nothing seems apparently wrong...
I also pulled the fuse for the E-Lock (Fuse #40 - 15 amp) but it made no difference whatsoever... I can't drive the truck anywhere and would prefer to avoid the towing charge involved in getting the truck to a local garage...
Has anyone else experienced a similar issue with advice? Thanks so much!
Kleats1217

 

Check your battery voltage and SOC (State of Charge). Low battery voltage during an engine start can cause all sorts of wierd things to happen.

Check the wiring under the hood, especially on top of the driver side wheelhouse. This area is prone to rodent damage and most of the wiring from the rear of the truck runs through those harnesses.

 

Thank you for the advice... I will check those areas...

 

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Curious:
Truck stopped running.
Limped back to driveway.
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Need to be enlightened a bit on this.
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Did the engine stop and you restarted it to move the truck etc.
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The E-Lock is done through the Trans Control Module.
Only way the truck would not move from a rear issue is E-Brake operation.
Or the rear end gears locked up for some reason.
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Difficult to help without all the info including code set.
Good luck.

 

Yeah... I started to drive forward and the error message appeared and the truck started to stall... I managed to get back home... I put a code reader on it and it came up with the code U0109 Lost communication with fuel module

 

The code involves the fuel delivery system.
No fuel, the engine stalls if the pump does not run.
The E- Lock harness goes to the rear,
Likely is a wire damage issue involving two separate functions in that Wire Harness.
E-LOCK Code should be preset. They can be P 1834, P 185 C/D/E, P 187 C/D/E, U 0140, U0100
Good luck.

 

Well, with a great deal of relief I managed resolve the "Check Locking Differential" error message... I put a code reader on the truck and it said "Lost communication with Fuel Pump Module... I went out and purchased a new Fuel Pump Module, thinking I'd have to replace it, and attempted to remove the old one. Ford had positioned the module on top of the cross member, just ahead of the rear differential, above the muffler, drive shaft and fuel tank. Trying to remove the old module was quite a challenge being as it was directly on top of the cross member. While trying to remove one bolt I felt loose wire end, which turned out to be a ground lead. As it turned out this was the reason for the error message in the first place. Ford decided to attach the ground wire right next to the module... The aluminum body is fabulous but the frame and undercarriage are often neglected and rust work away unseen, in this case for nine years...
Should you run into the same problem and you think you've checked all of the wiring harness and leads, have a feel on top of the cross member, that's where I found my problem...
Thank you to all those who read and responded to my post!
Kleats1217

 

Thanks for the update. I've had my fuel pump module off so I know what you are talking about.

 

You have no idea how much internet searching and dead end work I did on the truck before finding this thread and this post. I had taken off my FPCM but I did not see the loose wire up there. I was about to drop $120 at the dealer for a new one just to have the truck for Easter weekend. Sure enough I felt around up there and found a wire with no head. The bolt was rust fused, its still there. I just made a new hole in the cross rail and remaining ground wire spade. Starts up like a champ. Thanks again for actually posting your solution.