Hi, All,
The battery on my 2010 Super Duty XL goes flat in a few days of sitting. I don't have an amp meter, so starting pulling fuses to see if they sparked when being reinserted.
The dome light bulb was removed, so there shouldn't be any draw other than the clock and, I guess, the computer.
When I reinserted fuse 25, there was significant sparking. This fuse is for the underhood light, some sort of mirror extender and some sort of sun visor gear. Being a basic truck, I think the underhood light is the only one of the three it has.
I removed the underhood light, and the sparking was just as intense at the fuse location.
I have added LED headlights and powered running boards to the truck, as well as an aftermarket Nav system. The running board control plugs into the OBDII socket.
I doubt I patched anything into an unknown wire, but may have.
So, I assume a fuse only protects the things assigned to it in the manual, and nothing else.
Advice appreciated!
Joe
Colorado Springs

 

Get a multimeter. They aren't expensive and have lots of uses around the home, not just automotive. Will test both AC/DC, Ohms, Amperes, Continuity. Will pay for itself quick, with the diagnostic charges and shop labor rates anywhere from $60 to $120 an hour.

You could try using an inexpensive test light I guess.

 

F25 feeds the battery saver fed circuit.

You must wait 40 minutes after touching ANYTHING for the battery saver to time out.

Failure to do so will cause you to waste your time (and probably money).