Hello! I recently bought a new-to-me 2012 F-350 Super Duty Lariat Crew Cab with the 6.7 L diesel engine. For three weeks, she ran beautifully, but then, in the middle of her first long road trip, she wouldn't start.

Here's the background on what was happening at the time. I was driving for an extended period on the freeways. After a slightly longer pit stop than the previous ones, when I turned the key, the engine would not crank. I hear a click, then see the instrument lights (the blue ones that illuminate the dials, not the indicator lights) flash on and off and the seat moves into its memory position.

Important: I DO see the glow plug ("wait to start") indicator light for a bit, which then goes out once the glow plug is sufficiently heated. Additionally, the red battery indicator light and the yellow "engine" light are on--these do not go out.

Also Important: The truck starts like nothing ever happened after a jump.

In the weeks leading up to the road trip, I was having trouble with the rear dome light. I've replaced bulbs, fuses--still no joy there. If this is a wiring issue, this may be related.

Doing a little poking around, I have been able to rule out the following causes:
-Powertrain Control Module: When power on you get the glow plug light
-Bad Fuse #52/22 (controls PCM)
-Bad connections in wiring harness to the starter (controls PCM)
-Batteries: Replaced old batteries with new; swapped out old and new batteries into other vehicle. Both old and new batteries tested out ok. New batteries currently in the vehicle

I've come up with the following list of possible culprits:
-Bad starter?
-Ignition switch?
-Wiring Issue?
-Wiring harness to the starter?
-Cable running from battery to dashboard?
-Trigger wire from fender solenoid to solenoid on starter (esp. where bracket that holds the battery cable, it is located on the front, lower right of the engine)?

Does anyone know where I can get hold of a wiring diagram for this model? An engineering schematic where I can build a fault tree? I'm tearing my hair out trying to diagnose & fix this! Thanks in advance for all your help!

 

Start with the basics:

What is the state of the THEFT light when the "no crank" symptom occurs? A PATS event will disable the starter.

If it starts reliably with a jump, I'd tend to focus on the battery cables and connections. Your symptoms are of a failed connection that opens under load.

I buy copies of the factory service DVD off ebay.