5075E blowing start fuse when turning key

[Okinsis2005]

Good evening everyone! Need some help here...
Model: 5075E, non cab
After turning the key, the start fuse immediately pops. I can't find any shorts to ground in the circuit. Funny thing is, this happens when the PTO is not engaged.....when engaged, the key will turn to the start position without popping the fuse but the engine will not start. There is also an audible clicking sound from the relay that is second from the left inside the dash as if the relay is working but not transferring electricity to the starter., or starter solenoid if there is one. Not sure if this is an ignition, starter, starter solenoid, PTO, seat switch problem. I don't know much about tractors but I understand electricity well as an aviation electronics technician is the USN for 16 years. Any troubleshooting advice would be helpful.....standing by, thanks for the assistance!
Jayson

 

[beenthere]

To trouble shoot, I'd fashion up a 12v bulb on wires soldered to the blown fuse so you can "plug" that bulb into the fuse slot. If shorted, then the bulb will light. Gives you an opportunity to search for that short, be it a switch or a wire that is shorted out without the risk of having to put in a new fuse each time.

Hope that makes sense, and helps a bit.

:welcome: to TBN and thank you for your service time.

 

[JD5210]

I believe the problem is the thermistor sensor (thermistors are temperature variable resistors used as sensors.). On the thermostat housing there is a sensor that is connected to a two wire harness that goes to the injection pump; this is the "cold start advance" portion of the system so it starts easier when cold by advancing the timing.

When the sensor on the thermostat housing fails it shorts out and blows the fuse. Try unplugging it, replace fuse and see if it starts and runs. The part # is RE503242, if you are quick changing it, you don't have to drain the coolant, just make sure it's not hot at the time. You will want a pan under the tractor to catch the coolant, so as not too have to clean it up.

Power never gets to the injection pump when the PTO switch is on before the tractor starts since it is a safety switch, that is why the fuse does not blow.

If you do a search of this site on the part # RE503242, you will find this is a problem on the 3029 engine.

URL to JD parts
jdpc.deere.com/jdpc/servlet/com.deere.u90490.partscatalog.view.servlets.HomePageServlet_Alt

 

[Okinsis2005]

Thanks a million guys! I'll try the bulb and the thermistor resistor. Could you explain the exact location for me, I don't have a manual. M not near the tractor now but finding a water neck is pretty self explanatory. Thanks again, ya'll are super helpful!!!

 

[JD5210]

Please see attachment to help locate the sensor.

The 2 wire sensor is plugged into the top of the fuel injection pump. Just unplug it, replace the fuse and it should start.

 

[MF283]

The resistor went out on my 5303, it is a cold start advance, it will start & run unplugged. A word of caution, when you think it's tight, stop trying to make it tighter, it strips very easily as i found out & had to buy another one.

Ronnie

 

[Okinsis2005]

Thanks a million everyone, unplugging the harness worked perfectly and I have one on order. Deere quoted me $1700 for a new fuel pump, 3 different wiring harnesses, and the thermistor resistor harness and labor. All of you saved my butt! Don't have to worry too much about cold start, it's 90-100 everyday, coldest get to be about 50 but I'll have it fixed before season change. Again, thank you all for helping me and everyone else, you are true gentlemen.
Sincerely,
Navy Chief, JMO

 

[JKO1953]

Thank you.
My problem was exactly as you described. Your help saved me time and money. I will try to do the same for someone else.

 

[John Burelle]

Thanks folks. I am new to the forum but the information above may solve my problem. My 5075 shut down while I was operating and I found the start relay fuse blown. Replaced and it blew. This information has given me a better understanding of this system and I will try to repair tomorrow.

 

[little1406]

Many thanks to this forum. My John Deere 5055D blew its start relay fuse (repeatedly) and, after reading this thread, when I unplugged the sensor wires leading from the thermostat housing to the injection pump, the tractor started up properly!

How wonderful the Internet is for the repair of vehicles and machinery.

Scott Little