Check locking differential ~ open circuit

[WTX]

I searched on the forums a bit for this but nothing was specific to my problem.

I recently purchased a 2013 raptor and have been sorting out. I recently rebuilt the rear end, new locker, new R&P. Before the rebuild it gave me the “check locking differential” warning at start up. And after the rebuilt it’s still doing the same thing. I did notice the 4x4 knob was a bit screwy so I ordered another on eBay and just replaced. That did not solve the problem.

Forscan is giving me P187C differential lockup control circuit open. Which is in the TCCM. I pulled the plug in the back and I’m getting no power to it. I can hear the truck shifting into 4wd and back to 2wd.

It has to be a wiring issue. Has anyone experienced this?

 

[FordTechOne]

Here’s some information on how the system works:

Normal Operation

When the MSS is engaged to lock the rear differential, a PWM signal is sent to the ELD field coil by the TCCM through the differential lock control circuit. This PWM signal is initially 98% duty cycle to lock the differential and decreases to 40% duty cycle once the differential is locked. If the differential lock control circuit is open or shorted to ground, the TCCM senses a signal is not reaching the differential and sets a DTC.

Did you replace the ELD field coil during the rebuild?

 

[WTX]

Great info thanks

I assume the coil you’re referring to is in the differential? I replaced all components with all Yukon equipment. The locker claimed to be raptor only, the rebuilder said everything was hooked up upon rebuild. The old locker’s wires were screwed up, the mechanic thought it should work after rebuild but still getting the fault. He things it’s wiring up stream from the diff ?

 

[FordTechOne]

Great info thanks

I assume the coil you’re referring to is in the differential? I replaced all components with all Yukon equipment. The locker claimed to be raptor only, the rebuilder said everything was hooked up upon rebuild. The old locker’s wires were screwed up, the mechanic thought it should work after rebuild but still getting the fault. He things it’s wiring up stream from the diff ?

Correct, it’s located as shown in the attached picture. If it’s been replaced already, then there is likely an open in the circuit between the TCCM and the coils’s pigtail harness. You can ohm out sections of the circuit by unplugging inline connectors to isolate the open. Also pay close attention to pin fitment, spread or pushed out pins are the cause of many circuit issues.

 

[WTX]

Correct, it’s located as shown in the attached picture. If it’s been replaced already, then there is likely an open in the circuit between the TCCM and the coils’s pigtail harness. You can ohm out sections of the circuit by unplugging inline connectors to isolate the open. Also pay close attention to pin fitment, spread or pushed out pins are the cause of many circuit issues.

Thanks for the info. What are you doing tomorrow around lunch? Swing by. You can probably find it in 5 mins. Hahaha

I’ll start digging into it. Thanks for your help

 

[FordTechOne]

Thanks for the info. What are you doing tomorrow around lunch? Swing by. You can probably find it in 5 mins. Hahaha

I’ll start digging into it. Thanks for your help

Haha if only. If you'd like a copy of the Wiring Diagram just send me a DM.

 

[14BlackRoush]

Thanks for the info. What are you doing tomorrow around lunch? Swing by. You can probably find it in 5 mins. Hahaha

I’ll start digging into it. Thanks for your help

Hey mate, I’ve got the same issue, how’d you go working it out?

 

[WTX]

Sorry to hear that. My truck never got fixed, my brother is driving it now. I have not had a chance to work on it

 

[14BlackRoush]

No worries, will get in and try to sort it out this weekend, hopefully an easy fix as it was a simple problem that just popped up