Hello,

I have a 2010 F150 crew cab 4x4 with the 3V 5.4 in it. This one has the luxury FX4 package in it also.

I’m running into CAN issues. When I turn the key on, all the lights light up like normal and garages do there usual sweep motion but the passive anti theft system light beeps and rapidly flashes at me. Basically telling me it’s not recognizing the key and will not let the truck turn over at all. Initial code was a U0100 from my basic scan tool showing lost communication with ecm/pcm A. 

The truck was taken to a local mechanic who said it needed a new pcm. So, a new pcm was installed and 2 new keys programmed. However I am still having the same issue and the mechanic gave up and couldn’t figure it out.

I bought a breakout box and plugged it into the obd2 port to test the network. I am reading 120 ohms of resistance across pins 14 and 6 when it should read 60. I bought another scan tool that had more capabilities and scanned it again. It’s reading faults everywhere across multiple modules and I can’t communicate with the PCM. I bought a used instrument cluster thinking maybe the cluster was bad but the issue didn’t change.

The last test I ran today was testing resistance between pin 6 of the obd2 port with pin 59 of the PCM connector harness side and got less than 5 ohms of resistance which is good. I then tested resistance between pin 14 of the obd2 port with pin 43 of the pcm connector harness side and couldn’t get a reading so it was open. I ran that test based on recommendations from the workshop manual I have for the truck. I do have a full wiring diagram as well but it is a bit intimidating.

i have done a visual inspection of all the wiring I can see and don’t see an issue yet. Anyone have any idea on what my next step should be?