Case IH tAE – Central Controller (XCM) or Engine Control Module / Pump Control Unit (PCU): Vehicle CAN Chip, Data Valid But Above Normal Range

Communication failure or faulty connection on the Controller Area Network (CAN) bus between the tractor's central controller and the engine control module. When this code is active, the engine is typically enabled with no restriction on fuel or speed, but the hand throttle may be disabled, and the system may enter a limp-home mode.

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

1. 1

   Check battery and charging system to ensure voltage remains above 10V during cranking and the alternator is charging correctly

2. 2

   Verify if an external power supply or jump-starter was recently connected improperly, which can trigger this code

3. 3

   Test the engine shut-down relay (K5) for proper operation, as a sticking or failed relay can interrupt PCU communication

4. 4

   Inspect the wiring harness routing between the XCM and the engine control module for chafed wires (especially under the cab), loose connector pins, or corrosion

1. 1

   Power Down

   Turn the key switch to OFF and disconnect the battery (or pull the main ECU fuse) to prevent false readings or short circuits during testing.

2. 2

   Measure Circuit Resistance

   Disconnect the CAN bus connectors at both the XCM and the Engine Control Module. Set a multimeter to measure ohms. Touch the black lead to a clean chassis ground and use the red lead to probe the connector pins.

3. 3

   Check CAN Voltages

   If testing live, verify the CAN High and CAN Low voltages at the diagnostic connector. Healthy CAN bus lines typically rest around 2.4V to 2.5V.

4. 4

   Repair Wiring

   If you find a short to ground, an open circuit, or high resistance, locate the damaged section of the harness. Cut out the damaged wire, strip the ends, and use an OEM harness repair kit to crimp new pins or splice new wire with heat-shrink tubing.

5. 5

   Replace Relay

   If the K5 engine shut-down relay fails a bench test, replace it.

6. 6

   Clear Codes

   Reconnect all modules and the battery. Use the Case IH Electronic Service Tool (EST) or the tractor's H-Menu diagnostic interface to clear the stored fault codes.

7. 7

   Module Replacement (Last Resort)

   If the wiring, relays, and voltages are all perfectly within spec, the fault lies internally within the Vehicle CAN chip on the XCM or PCU. The affected controller will need to be replaced and recalibrated by a dealer.