The car is a 1997 Crown Vic with the 4.6 liter engine and 160,000 miles. The 50 amp IG SW fuse for the starter relay blows within seconds after it is inserted into its slot (the second one in line) in the high current fuse panel. What is the most likely source for the short / overload?
The clock and the radio do not work even though all the other fuses seem to be good.
It looks like the 50 amp ignition fuse goes straight into the ignition switch.
You can use a tool called a short checker to put in place of the fuse to help diagnosis the problem safely. It is a circuit breaker that will continue to pop when installed. It will help protect the circuit from overheating.
Then start disconnecting components starting with the ignition switch.
When you find the problem the short checker will stop popping.
If it continues to pop, check the wiring from the fuse panel to the ignition switch for any wires that may be grounded to any metal on the car.
Last edited by TechHelp2 (1/9/2010 8:20 AM)