Case IH t8B – Engine Control Unit (ECU) / Pump Control Unit (PCU): Shut-Off Signal, Data Valid But Above Normal Range

This code indicates that the electrical signal controlling the fuel shut-off solenoid is registering a voltage that is higher than the expected normal operating parameters. This typically points to a short to a high-voltage source in the wiring harness, a failing solenoid coil, or an issue with the power supply to the pump controller. If this component fails, the tractor may either refuse to start or refuse to shut down when the key is turned off.

• MXM
• MXM 120
• MXM 130
• MXM 140
• MXM 155
• MXM 175
• MXM 190
• MX100
• MX110
• MX120
• MX135
• MX150
• MX170

1. 1

   Inspect the wiring harness leading to the fuel shut-off solenoid on the injection pump for chafed wires, damaged insulation, or areas shorting to a power source.

2. 2

   Disconnect the electrical connector at the solenoid and check for moisture, dust, or corrosion that could be bridging connections and causing a short.

3. 3

   Test the solenoid coil resistance with a multimeter to check for internal failure.

4. 4

   Verify that the voltage being supplied by the PCU is within the correct 12V specification.

1. 1

   Prep the Machine

   Turn off the tractor and disconnect the battery to prevent any electrical shorts during the repair.

2. 2

   Locate the Solenoid

   Locate the cylindrical fuel shut-off solenoid mounted on the fuel injection pump.

3. 3

   Disconnect

   Unplug the electrical connector from the solenoid.

4. 4

   Remove the Old Unit

   Unthread and remove the old solenoid from the injection pump. (Note: On some earlier tractor versions, you may need to remove a mounting bracket to mount the new fuel solenoid directly to the injection pump).

5. 5

   Install the New Unit

   Thread the new replacement solenoid into place and tighten it securely.

6. 6

   Reconnect

   Reconnect the electrical connector, ensuring the connection is clean and tight to withstand farm work vibration.

7. 7

   Test

   Reconnect the battery. Turn the key to verify the solenoid operates. Start the tractor, then turn the key off to ensure the engine shuts down cleanly. Clear the fault codes from the instrument cluster.