2010 Mercury 50 EFI blowing fuse

[braintree]

I have a 2010 50ELPT EFI motor that is blowing a fuse when I turn the key. I was planed off and cruising the other day and the motor just shut down. No power to key or even trim switch on motor. The battery is fully charged and we checked that it was working by testing the bilge pump. I replaced the 15amp fuse and the trim worked fine. As soon as I touched the key it blew again. I searched but didn't find a conclusion to the problem. I just bought the Seloc manual and and having trouble locating anything to identify what the fuse controls. I found the wiring diagram but no further explanation about the fuse box and fuses. Any help/guidance is appreciated.

 

[Texasmark]

If you have the manual you should have a wiring diagram. Since movement of the key causes the problem, I'd start with the key terminal that is the output. Follow the red/purple stripe or purple wire (whichever your engine has) which is the "switched 12v supply} from the switch (via your diagram) to the locations where it is routed. If you don't have an ohmmeter to check for low resistance to ground (batt. -) remove every connection which is tied to that line.

After doing that, new fuse, and switch to on. If it blows again, you have a problem in your ignition switch or in the wiring, probably external to the engine, probably in the control box....friction cutting through the insulation associated with movement of the throttle/shift control.

If it doesn't blow, start plugging things back in, one at a time till it does. There's your smoking gun.