'11 F-550 No-Crank/No-Start BCM Fried?

mchan68 · July 20, 2012

Got one in on the hook yesterday, that came in from another shop that just did a DOT inspection and an aftermarket trailer brake control install that wouldn't start after they did the work. Mileage is unknown due to a dead IC. The IC does not respond to ignition key inputs. Funny this is, I was able to retrieve DTCs P068A, U0073, U0100 and U0140. There is B+ on both sides of BCM fuse #28. Not sure where else to go with this. According to the tech that did the work mentioned above, he did disconnect the batteries when he did welding on the frame (this vehicle is a dump body), as well as the trailer brake install. Ran a network test, and all modules PASS expect for the ACM and BCM. Just curious if anyone else has ran into something similar? To me, it stands to reason that if the truck drove into the shop, and wouldn't start after they did the work, SOMETHING they did must've pissed off the BCM from what I'm seeing so far.

mchan68 · July 25, 2012

Just an update to this. It turned out that the tech that did the aftermarket trailer brake controller install, snipped the connector off that is supposed to connect to the factory tralier brake controller on vehicles so equipped. I guess this one just plugs into an empty spot behind the coin holder on these applications without the factory controller option. It turned out that he had cut the main HS-CAN + and HS-CAN - circuits and left them dead-end, creating an open between the BCM and data link connector. I find it hard to believe that that circuit would end at a trailer brake connector instead of just being one piece with the main instrument panel harness. Oh well, I'm glad to get this one out of my hair.

lmorris · July 25, 2012

Our other tech had the same issue, no start after TBC install. Only these guys managed to actually short out the BCM and fried it. New BCM fixed her right up.

mchan68 · July 26, 2012

Our other tech had the same issue, no start after TBC install. Only these guys managed to actually short out the BCM and fried it. New BCM fixed her right up.

Hotline told me to ohm out pins 6 and 14 of the DLC to take a reading. If 60 ohms, all modules are online. If 120 ohms, there is a module (or modules) offline. They also advised me to ohm out pins 16 and 17 on the BCM where C2280F connects. If 120 ohms was retrieved, the BCM would be in need of replacement (according to them anyways). Coincidentally, there was another tech in the shop in the process of replacing an evaporator on another Super Duty truck with the dash and heater box out, so I borrowed the BCM off of it and ohmed out the same two pins. Sure enough, I got the same 120 ohm reading so I called BS on their advice and dug deeper. What threw me off was having BOTH the HS-CAN circuits open. It never dawned on me that it would dead end at the TBC connector. I was almost ready to gut the dash to chase the opens. Oh well, live and learn.