Case IH P46 – Engine Control Module (ECM): CAN CCVSS Message, Data Incorrect

The Engine Control Module is receiving a faulty vehicle speed signal from the central controller (XCM) over the CAN bus. While the engine remains enabled with no restriction on fuel or speed, the external service tool may not be usable, and automated transmission/cruise functions will be impaired.

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

1. 1

   Inspect the transmission mid-speed sensor connector (C037) and the output speed sensor connector (C038).

2. 2

   Verify Connector Placement: A common failure mode is that the mid and output speed sensor connectors have been accidentally swapped during previous maintenance.

3. 3

   Check the Extension Harness: Inspect connector C020. Ensure the connector is fully seated, not damaged, the pins are in the correct position, and the fit is tight.

4. 4

   Continuity & Resistance Testing: Power OFF the tractor and turn the keyswitch OFF. Disconnect connectors at both ends of the circuit to prevent false readings. Set a multimeter to measure resistance (ohms). Use the black lead to make contact with a clean, plated metal part on the chassis (like a jump start post) and the red lead to touch the connector pins one at a time. A reading of 3 to 4 ohms indicates the circuit is continuous. Higher resistance indicates dirty or corroded terminals, while 100K ohms indicates an open circuit.

1. 1

   Power Down

   Turn the keyswitch OFF and disconnect the battery if specified by standard safety procedures.

2. 2

   Inspect and Correct Swapped Connectors

   Locate connectors C037 and C038 on the transmission housing. If they have been swapped, disconnect them and reconnect them to their correct respective sensors.

3. 3

   Clean and Repair Wiring

   If the connectors are routed correctly but show high resistance or voltage shorts, clean the pins. If the harness is damaged, use an OEM harness repair kit to splice in new wiring or replace the damaged connector.

4. 4

   Replace Faulty Sensors

   If the wiring harness tests perfectly but the speed data is still incorrect, the inductive magnetic proximity speed sensor itself has likely failed internally and must be replaced.

5. 5

   Clear Codes and Test

   Once the repair is made, clear the error code using the electronic service tool or tractor display. Start the tractor and test drive it to ensure normal operation and verify that the code does not return.