I have a 2001 F350 7.3l PSD. It has 408k on it. Pretty much stock. I am having a problem, that I can't find any info on. When I turn the key to the "on" position, I hear clicking from a relay or something under the dash in the area of the radio, then all power goes out. No headlights, interior lights nothing. I turn it off for a while and when I try again it does the same thing. Batteries are good, clean posts and cables, I checked the grounds from the battery, but not sure where the firewall ground is.

Any suggestions?

 

Are you seeing the WTS light in the instrument cluster?

What was the resting voltage of the batteries?

There is a large ground above the PCM on the engine side of the firewall for a lot of the major systems.

 

Did you load test each battery?

 

If automatic, wiggle gear shifter as key is turned. Might be as simple as tightening gear shifter.

 

The grounds identifier numbers begin with G as in GXXX. Also find the ground strap from the Engine to the chassis and the tranny to the chassis and check them.