Hi there I'm working on a 2005 f250. The dash goes out on start up and well as driving. I checked all fuses under the dash as well as under the hood everything seams ok . I checked shifter for the O/D wire worn but was.. I'm at a
Stand still. Next thing I'm thinking is the immobilizer . If any one has a input would be great thanks

 

My 06 had issues like this.
I bought the truck new in 06.
The first symptom, which showed up about 2008 (about 30,000 miles), was the speedometer not returning to zero.
Then, about 2011 (about 75,000 miles), the security system would trigger spuriously, sometimes at night (neighbors loved it; not really).
Next, about 2012 (about 90,000 miles), the dome light would turn on while I was driving the vehicle, eventually staying on permanently in early 2014.
I tried swapping out each relay, one at a time, but none of them was the problem, the dome light still stayed on. I found out there are 2 relays inside the gauge cluster, one is the cab light relay, the other is a power saver relay. Since I didn't want to pull the gauge cluster myself (for fear of not getting it back together right), I took it to the dealer. They diagnosed it to be a faulty gauge cluster. They said they do not diagnose this part down to the individual component, but replace the entire gauge cluster with a rebuilt one. This cost me about $700.
All my symptoms were fixed by replacing the gauge cluster except, one, which I have not mentioned yet.
This last symptom was a chime, whenever the door was opened, even without the key in the ignition. The cause of the this was the timer spring, which they replaced for about $500.

Hope this helps.

Oh, the gauge cluster issue was a short, which caused my batteries to discharge to the point of not being able to start, if I didn't drive it every day.
The batteries stay charged now for at least a week...I haven't had the truck sit for more than a week yet, so, I don't know how long it will sit before failing, but I think it's as good as it was new, at this point.