I've got a Deere 750J that the fan runs wide open by default. The guys who had it before me somehow got the wires caught in the fan and tore them up. I spliced all the wires back to how they should be and checked for bare wires to prevent a short circuit. There was no voltage going to the solenoid on the H02 wire so I checked that g11 was grounded properly to the starter and appears so. I chased H02 all the way back to the TCU and there is no power coming out of the TCU to power the solenoid. I ran the machine for a bit to let it warm up slightly before I checked just in case the machine calls for full fan to warm up when cold. Looking for wisdom on the variable fan drive function, is there a warmup cycle on those machines? What temps does it send voltage to the fan to slow it down? Is the TCU likely fried from the fan incident or is there a fuse somewhere that I'm missing? TIA
Please post the machine serial number. Any codes?
S/N: T0750JX133647 Active Code "Fan Drive Sol Short Circuit TCU 1071.6"
Check your fan proportional solenoid resistance. That solenoid should be mounted on the fan motor, according to your serial number. It should be 27-30 ohms. If it is within spec, then check the wiring for shorts to ground. There will not be any voltage out of the controller if it detects a short. The driver will shut down in that situation.
Resistance on the solenoid is good, exactly 27 ohms. I pulled a power wire off of the positive terminal on the battery and ran it up to the fan. Checked the ground on g11 with the power wire and it is grounded. Checked g11 again closer to the starter and was good. There is a dead end wire for g11 up at the TCU that I would imagine is there to check for a short circuit? I do not have a ground when trying to ground with the g11 wire at the TCU but it grounds everywhere else.
The G11 Black only runs from the solenoid to the starter, according to the schematic. Do you have the schematic? Were the wires H02 and G11 load tested? If you have a good H02 Green wire from the TCU to the solenoid, and a good G11 Black to the starter, then either you have another temperature sensor circuit telling the TCU to run the fan at full speed, or you have a bad driver in the TCU. If there is a bad temperature sensor elsewhere on the machine, or an open wire in one of those sensors, the fan will run at full speed (no voltage to the solenoid).
I have a schematic for a machine with the reversing fan but figured it should be the same minus that extra circuit. Do you have any idea of why g11 is up at the TCU with a shrink tubing on the end of the wire? There is another one for the other plug on the TCU as well. I have not done a load test on the circuit. I will look at some diagrams and find all of the temp sensors, do you know off the top of your head how many are on that machine? I am assuming 3.
The black wires that are heat shrinked are shielding wires for the "CAN" network wires. The black capped wires at the controller should be labeled R13. All the temperature sensors can be seen in the monitor while in the service mode. Service mode is entered by keying on, pressing and holding the menu button until the monitor beeps and the words SERVICE MENU appear in the screen. Then navigate to Diagnostics/Live Values. Check your messages.