Case IH P80 – Pump Control Unit (PCU): Pump Map, Data Valid But Below Normal Range

The Pump Control Unit (PCU) internal software map is not programmed or is missing data, which typically results in an immediate engine shut-down.

• MXM
• MXM 120
• MXM 130
• MXM 140
• MXM 155
• MXM 175
• MXM 190

1. 1

   Ensure the power is OFF and the keyswitch is OFF, then disconnect connectors at each end of the circuit to prevent false readings

2. 2

   Inspect connectors C273 and C316 for damaged pins, corrosion, or loose connections

3. 3

   Check for Short to Positive Voltage: Disconnect connectors C273 and C316, turn the keystart ON, and measure the voltage between connector C273 pin 8 and ground

4. 4

   Check for Open Circuit: Turn the keystart OFF, then measure the resistance between connector C273 pin 8 and C316 pin 35, and between C273 pin 6 and ground

5. 5

   Check for Short to Ground: Check continuity between connector C273 pin 8 and ground

1. 1

   Check for intermittent circuit

   While performing the diagnostic checks, wiggle the wiring harness and the connectors to check for an intermittent circuit.

2. 2

   Repair or replace wiring harness

   If a voltage is indicated during the short-to-positive test, or if the resistance indicated during the open circuit test is greater than 5 Ohms, or if a short to ground is indicated, you must repair or replace the wiring harness as required.

3. 3

   Diagnose faulty PCU

   If the wiring harness and connectors test perfectly (resistance is approximately 5 Ohms and no shorts are found), the failure mode is a faulty Pump Control Unit (PCU).

4. 4

   Replace fuel injection pump

   Because the PCU is integrated into the pump assembly, the official resolution is to remove and replace the fuel injection pump.

5. 5

   Update software

   After replacement, ensure the tractor's XCM and PCU software are updated to the latest versions to prevent false code displays.