JD 4500 thermistor location

[glenthale]

Here is a challenge... I needed to replace the thermistor on my 4500 (the tractor was having fuel shutoff solenoid problems). On one schematic the thermistor is shown on the back of the fuse panel behind relay #3... it was not there. Then I found another schematic that shows a white and black wire to and from the thermistor. I checked the back of the relay and found these and the wires headed into the main harness. I cut and soldered in a new thermistor and the unit runs fine. I have searched the unit and cannot find the thermistor, I do not want to get into the main wire harness and the local JD mechanic has never changed one of these.
Does anyone out there know where the thermistor on the 4500 series is located as I would like to get the unit back to OEM specs.

 

[beenthere]

:welcome:

I'll get out the tech manual and take a look. Found where it says it is located on the load center, and specifically the thermistor has a black and white wire plugged into the #87 (white) and #85 (black) spades on the K3 Fuel Shutoff relay.

Also, a search of the forum on "thermistor" brings up previous discussions, one of which describes the size of the thermistor on the back of the "fuse" panel

http://www.tractorbynet.com/forums/parts-repairs/88130-john-deere-4400-hard-start.html

 

[glenthale]

You are correct.
But there are two (2) black wires on the back of K3, one of which goes to K2 (start relay) and as I stated the other black wire, and the white head off into the main bundle.
FYI, I snipped the black and white that goes to the main bundle and installed the new thermistor there which enabled me to connect 85 and 87 and disable the existing thermistor. The unit is up and running. I will start physically tracing out the line when I get a bit more time available.
For the record... the tech manual drawings are correct. I did pull the red stops off the backs of 85 and 87 and removed the lugs, cleaned them and verified the thermistor was not there and then reassembled.
My next step will be to contact JD tech support.
Thanks.

 

[atschirner]

Glen,
Unless you just want to know where the old thermistor is located you can abandon it in place. You have removed it from the circuit when you installed the new one so it would be okay to let it R.I.P.

On my 2000 4400 it is external to the harness but it sounds like that has changed on your tractor.

Best, AT

 

[glenthale]

Thank you all for your assistance in this matter.
Respectfully
GT

 

[RoyJackson]

Thank you all for your assistance in this matter.
Respectfully
GT

Did you buy the tractor new, or used?
If purchased used, it's a possibility the previous owner didn't do such a good job following the schematic...

Just curious...