Case IH 51073 – AUX / TMF: Aux 3rd Lower Coil solenoid shorted to 12 volts

The controller is detecting unexpected voltage on the circuit for the lowering solenoid of the 3rd auxiliary remote hydraulic valve. This is typically caused by the signal wire shorting directly to a 12-volt power source in the wiring harness, or an internal short circuit within the solenoid coil itself.

• MX Magnum
• Case IH MX Magnum Series
• MX180
• MX200
• MX220
• MX240
• MX255
• MX270
• MX285
• Case IH TG Series

1. 1

   Visual Harness Inspection: Inspect the wiring harness leading to the rear remote hydraulic valves. A common issue on these tractors is the wiring harness rubbing against hydraulic pipes, which wears through the insulation and shorts the wires to power or ground.

2. 2

   Voltage Check: Disconnect the electrical connector at the 3rd remote valve's lower solenoid. Turn the key ON (engine off). Probe the signal wire to see if 12 volts is present when the valve is not being commanded to lower. If 12V is present, the wiring harness is shorted to power.

3. 3

   Coil Resistance Test: Measure the resistance across the pins of the disconnected solenoid coil using a multimeter. If the resistance is near zero, the coil is internally shorted and must be replaced.

4. 4

   Controller Pin Check: Inspect the pins at the AUX/TMF controller for corrosion, moisture, or bent pins that could be bridging a 12V supply to the 3rd lower coil circuit.

1. 1

   Disconnect Power

   Turn off the tractor and disconnect the negative battery cable to prevent electrical spikes.

2. 2

   Locate the Component

   Go to the rear of the tractor and locate the remote hydraulic control valve stack. Identify the 3rd valve slice (usually counted from left to right or inside to outside depending on the exact plumbing) and locate the lower coil solenoid.

3. 3

   Repair Wiring (If Applicable)

   If the diagnostic checks revealed a chafed wire rubbing on a hydraulic line, cut out the damaged section, splice in new wire using weather-resistant heat-shrink butt connectors, and wrap the harness in protective loom. Reroute the harness away from the hydraulic pipes and secure it with zip ties.

4. 4

   Replace the Solenoid (If internally shorted)

   Unplug the electrical connector from the solenoid. Remove the retaining nut or clip holding the coil to the valve cartridge. Slide the old coil off the cartridge stem. (Note: If the cartridge itself is leaking or damaged, unscrew the cartridge from the valve body. Have a catch pan ready for hydraulic fluid. Install the new cartridge with new O-rings lubricated in clean hydraulic oil). Slide the new solenoid coil onto the stem and secure it with the retaining nut/clip.

5. 5

   Reassembly and Testing

   Reconnect the electrical harness. Reconnect the battery. Start the tractor, clear the stored fault codes from the display, and cycle the 3rd remote valve lever to ensure the code does not return and the hydraulics function properly.