Case IH P42 – Engine Control Module (ECM): Msg1 Message, Shorted To High Source

Communication failure or faulty connection between the Engine Control Module (ECM) and the Pump Control Unit (PCU). The system detects a short to a high voltage source on the CAN BUS lines, which restricts the engine speed 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 keystart to the ON position and measure the voltage between connector C273 pin 1 (5420–G) and ground, and then C273 pin 2 (5400–Y) and ground.

2. 2

   Wiggle the harness and the connectors to check for an intermittent circuit. If a voltage is indicated where it shouldn't be, the harness is shorted.

3. 3

   Check the CAN BUS wires (Y) and (G) to ensure they are properly twisted together and free from possible interference or chafing.

4. 4

   Turn the key OFF, disconnect connector C273, and measure the resistance between connector C273 pin 1 (5420–G) and C273 pin 2 (5400–Y).

1. 1

   Repair or replace the engine wiring harness

   If the voltage/wiggle test revealed a short to a high voltage source, repair or replace the affected engine wiring harness.

2. 2

   Replace the Engine Control Module

   If the resistance measured across the CAN BUS terminating resistors (C273 pins 1 and 2) is not approximately 120 Ohms, the internal resistor in the ECM has failed. You must remove and replace the Engine Control Module.

3. 3

   Replace the Fuel Injection Pump assembly

   If the resistance indicated is approximately 120 Ohms, the CAN BUS terminating resistor in the ECM is functioning correctly. This isolates the failure to the Pump Control Unit (PCU). Because the PCU is integrated into the pump, you must remove and replace the Fuel Injection Pump assembly.