Case IH P3F – Engine Control Module (ECM): PSG Message, Data Valid But Above Normal Range

Indicates a communication or data range error between the Engine Control Module (ECM) and the Pump Control Unit (PSG). The ECM is receiving a message from the PSG that is formatted correctly (valid) but contains data values that exceed the normal operating threshold. The engine remains enabled, but the system enters a derate mode, restricting the maximum engine speed to 1760 RPM.

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

1. 1

   Visually inspect the wiring harness and connectors between the ECM and the injection pump for corrosion, chafing, or loose pins

2. 2

   Perform an open circuit check: disconnect connectors C273 and C316, measure resistance between C273 pin 5 and C316 pin 20, and C273 pin 6 and ground (wiggle harness during testing to check for intermittent breaks)

3. 3

   Perform a short to ground check: measure resistance between C273 pin 5 and ground, and C273 pin 7 and ground

4. 4

   Perform a short to positive voltage check: disconnect connector C315, turn key switch ON, and measure voltage between ground and C273 pin 5, C273 pin 7, and C315 pin 18

5. 5

   Ensure there is no electrical interference on the CAN BUS lines communicating with the pump

1. 1

   Power Down

   Turn the key switch OFF and disconnect the battery to prevent electrical spikes.

2. 2

   Isolate the Harness

   Disconnect the affected connectors at the ECM and the injection pump.

3. 3

   Test the Wiring

   Perform the multimeter checks outlined in the diagnostic section.

4. 4

   Repair Wiring

   If an open circuit, short to ground, or short to voltage is found, repair or replace the engine wiring harness.

5. 5

   Replace the Injection Pump / PSG

   If the harness tests perfectly, the fault lies within the Pump Control Unit (PSG) itself. Replace the entire Bosch VP44 fuel injection pump assembly (or have a specialized diesel injection shop rebuild the pump and replace just the PSG module).

6. 6

   Calibrate and Clear

   After installing the new pump, bleed the fuel system, clear the stored fault codes using a diagnostic service tool, and test-run the tractor to verify that full engine RPM is restored.