Case IH t8A – Engine Control Unit / PCU (Powertrain Control Unit): Shut-Off Signal, Data Valid But Below Normal Range

The engine controller is detecting that the electrical signal from the fuel shut-off circuit is lower than the expected normal operating range. This typically points to a failing fuel shut-off solenoid coil, high resistance in the wiring, or a short to ground preventing the injection pump from receiving the proper voltage to control fuel flow during engine shutdown.

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

1. 1

   Check the electrical harness and the connector at the fuel shut-off solenoid for corrosion, loose pins, or physical damage caused by heat and vibration.

2. 2

   Verify that proper voltage (12V) is reaching the solenoid when the ignition key is turned to the ON position.

3. 3

   Check if the tractor is experiencing physical symptoms like failing to start or refusing to shut down when the key is turned off, which indicates internal leaking or mechanical binding of the solenoid.

1. 1

   Disconnect battery

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

2. 2

   Locate solenoid

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

3. 3

   Disconnect wiring

   Disconnect the electrical wiring harness connector from the solenoid.

4. 4

   Remove old solenoid

   Unthread and remove the old solenoid unit from the injection pump housing.

5. 5

   Clean mounting surface

   Clean the mounting surface and threads on the injection pump.

6. 6

   Install new solenoid

   Thread the new replacement solenoid into place. (Note: Depending on the replacement part used, updated mounting bolts may be required).

7. 7

   Reconnect wiring

   Reconnect the electrical connector, ensuring the connection is clean, tight, and fully seated to prevent future moisture ingress.

8. 8

   Verify repair

   Reconnect the battery, start the engine, and cycle the key off to verify that the engine shuts down cleanly and the fault code clears.