03 and up Ford 6.0 no comm

I wanted to share a time saving tip that I figured out after numerous no start diagnostics on these vehicles. As a mobile tech I need to get in and out as fast as possible so I am always looking for ways to get the most amount of information, in the shortest amount of time, so I can be 100% accurate on my diagnostic. Everyone has their own methods and that's great as long as it's producing great results. So I have had a few 6.0 Ford diesels that I was called out to program a new pcm on that would not communicate. Many techs don't realize that on most vehicles the module needs to communicate before it can accept software. So you hook up IDS or whatever scan tool you are using and it won't communicate with the pcm. Or in the case of ids it simply won't let you get past the vehicle id screen. Here's what I have found that has not let me down yet. Hook up your dlc breakout box and scope 6&14. If CAN high and CAN low are sitting at ground, go out to the powertrain control module (front of left inner fender) and unplug the center connector. Now recheck for communication / CAN bus activity. If it now works then you can likely skip the time consuming task of verifying the integrity of the powers, grounds, CAN lines, and / or wake up circuits. Unplugging this middle pcm connector opens up the 5 volt reference circuit removing the short to ground the was killing communication. It appears there is a tie in between the ref circuit and the can transceiver inside of the pcm. The 5 volt power supply for the ref circuit must feed the can transceiver, which would explain why both are affected when there is a short to ground on the ref circuit. I've supplied a couple of pictures of the connector. If you are looking at the front of the pcm, the far left connector is mainly powers, grounds, can lines, sensors, and ref supply for the map, baro, and APP. The middle one is mainly 5 volt ref and engine sensors. The smaller of the three, on the right side is all transmission related. Something interesting that you might notice is that there is only one 5 volt ref wire leaving the middle connector that supplies ref power to most of the sensors and fan clutch. Finding the short will be the fun part. At least you will only have 5 minutes into it up to that point if this time saving method has helped you. 

" Success is the ability to go from failure to failure without losing your enthusiasm "