250 skid steer, replaced 15amp key switch fuse, turn key on, immediately blows fuse. What do i check next?

hey thereCustomer

It's very difficult to diagnose electrical problems without a schematic. I get calls for this type of stuff all the time during my busy season.

On a John Deere 250, things that come to mind that are energized with keyed power are the fuel pump and the fuel shutoff solenoid, perhaps something in the dash.

I would unplug the fuel shutoff solenoid, the electric fuel pump at the right rear of the pump, then all the fuses and relays. Put a fresh fuse in the key switch fuse and turn the key on. If the fuse pops, then the problem is either a bad keyswitch or in the wiring going to it.

If the fuse holds, plug fuses back in to their respective sockets one at a time. This may blow the fuse again at any time, but noting which fuse makes it blow helps identify where the trouble my lie.

If you can plug all the fuses back in without blowing the keyed power fuse, then begin plugging in relays, one at a time, in the same manner as the fuses. If plugging in a relay blows the fuse, you can isolate a bad relay by switching them around with the lights or something that is on a switchable circuit.

If you can plug in all relays without blowing a fuse when you turn the key on, then plug in the fuel shutoff, then the fuel pump. If either blows the fuse, then it is either that component has failed or the wiring going to it from the relay is shorted to ground.

These types of tests are very general electrical troubleshooting tasks when you don't have access to schematics, and can be used for all kinds of machines, but it does require that you have some extra fuses on hand.

Sometimes, I need to call my local dealer and get a copy of the schematic faxed to me. Depending on who I talk to and his mood that day, I am sometimes told to buy a manual....=). Not much help.

If you feel that you would rather have an answer from someone who has access to a schematic and can talk you through that way, let me know and someone else may try and help.

If you try any of the tests and get stuck, also let me know with details and I'll assist you further.

Hello againCustomer

I had intended that you find the problem before you accepted the answer, but thank you very much!

If you have any problems, reply to this thread and we will get it resolved.