Case IH t40 – Engine Control Module (ECM) and Pump Control Unit (PCU): PSG Message, Shorted To High Source

This code indicates a communication failure or faulty connection between the Engine Control Module (ECM) and the Pump Control Unit (PCU). When this fault is active, the engine remains enabled, but the engine speed is restricted to a maximum of 1760 RPM as a protective measure.

• MXM
• MXM 120
• MXM 130
• MXM 140
• MXM 155
• MXM 175
• MXM 190
• TM120
• TM130
• TM140
• TM155
• TM175
• TM190

1. 1

   Turn the power OFF and the keyswitch OFF, then disconnect the connectors at both ends of the affected circuit to prevent false readings

2. 2

   Inspect the CAN BUS wiring between the injection pump (PCU) and the ECM for chafing, corrosion, or swapped connectors

3. 3

   Perform continuity and ground testing using a multimeter to measure resistance (ohms) between a chassis ground and the connector pins

4. 4

   Verify that the CAN bus messages between the PCU and the ECM are not suffering from interference or an impaired value range

1. 1

   Locate the Fault

   Use the resistance measurements to pinpoint the exact location of the short to a high voltage source in the wiring harness.

2. 2

   Harness Repair

   If a wire or connector is damaged, disconnect the affected connectors and pull back the harness outer covering. Use an appropriate harness repair kit and pin removal tool to extract the damaged pins. Splice in the required length of new wire following the original harness routing, and insert the new pins into the connector.

3. 3

   Component Replacement

   If the wiring harness and connectors test perfectly, the fault lies within either the Engine Control Module or the Pump Control Unit (which is integrated into the fuel injection pump). Replace the faulty module.

4. 4

   Clear and Test

   Once the physical repair is complete, use the diagnostic tool to clear the error code from the system memory and test the tractor to ensure normal operation and full RPM range.