F250 electrical problem
 

2001 F250 5.4
Intermittent problem. About every 10 starts the whole truck goes dead upon turning key to start. It is as though the battery is disconnected by some relay or breaker. Battery tests good. Grounds are solid. Truck will start after a period of time ranging from 10 seconds to as much as an hour. 9 times out of 10 truck starts normally.

Is there a relay or disconnect that cuts the positive 12volts to the truck?