Case IH 2762 (3042.10) - DEC – DEC: CAN 2 - PB_UCM5_27 absent on CAN2

A data message or node identified as "PB_UCM5_27" is completely missing ("absent") from the CAN 2 data bus, meaning the DEC is no longer receiving the expected broadcast from the UCM5 node.

• MAXXUM T4E

1. 1

   Verify the battery voltage and system grounds, as low voltage can cause modules to drop off the CAN bus.

2. 2

   Identify the physical location of the DEC and UCM5 modules.

3. 3

   Inspect the CAN 2 network wiring harness for erratic, intermittent, or incorrect data connections.

4. 4

   Check the CAN 2 bus terminating resistors using a multimeter (typically reading around 60 ohms across the CAN High and CAN Low pins with the battery disconnected).

5. 5

   Inspect the connectors at the UCM5 module for pushed pins, corrosion, or moisture ingress.

1. 1

   Disconnect battery

   Disconnect negative battery terminal.

2. 2

   Trace wiring harness

   Trace the CAN 2 wiring harness between the DEC and the UCM5.

3. 3

   Repair wiring

   Repair any chafed, broken, or shorted wires found in the CAN 2 twisted pair.

4. 4

   Clean and re-seat connectors

   Clean and re-seat the connectors at the UCM5 module.

5. 5

   Replace UCM5 module

   If the wiring and power/ground to the UCM5 are intact but the module still fails to broadcast on CAN 2, replace the UCM5 module.

6. 6

   Verify repair

   Reconnect the battery and clear the fault codes to verify the repair.