Hi so I am new to diesel's and am having a problem that even my two local ford dealers can't figure out. So here it goes. I have a 05 6.0 with about 115000 miles on it. I bought it broke down I did head gaskets egr delete and a new ipr when I. First got it. That fixed it and I drove it problem free for about two years. Then one day it started having problems what it would do is. Cold it would start and run perfectly. But when it got to operating temperature if you shut it off it would not restart until I got cold again and then it would start and run perfectly again. Well then after about a month it went to just not starting at all. Well I have a couple of friends with other 6.0s so I took and tried changing the pcm off another 05 on mine nothing changed still no start. Well then I tried a 03 pcm and it starts and runs perfectly other than the gauges don't work. Well my pcm will start both the 03 and the other 05 but not mine. My truck will only start with the 03 pcm. Well the dealer had me buy another pcm they programed it but still nothing. Well then they thought it was the smart junction box so they put that in and still nothing but it still will start with the 03 pcm just no gauges. Any thoughts?

 

Harness issue perhaps. The connectors for the pcm and ficm are PITAs and if arent connected just right they wont work properly. Another issue is the wires chaffing...go through the whole harness and look for damage to the harness

 

Hi thanks for the reply it just doesn't make sense if it was a harness issue it would start with the 03 pcm but not the 05 are there differents as far as sensors

 

Nothing makes sence when it comes to writing harness. You said the head gaskets were replaced the very well could have pinched a wire putting the cab back on. Wire heats up and shorts out. The 03 could be bypassing that circuit. Maybee a sensor that 05s have and not 03.

 

Also I would look up power stroke experts in your area. Dealers are good for common problems but its been my experience that if it don't through a code there lost. But an old school self owned and operated mechanic that specializes in power strokes my have already came across this issue before