JCB P0181-87 – Engine ECU: Missing Fuel Temperature CAN Message

The system has detected a loss of communication regarding the fuel temperature signal. A control module on the machine has not received the expected CAN bus message containing fuel temperature data broadcast by the Engine ECU. The '-87' suffix specifically indicates a missing CAN message, pointing to a communication network failure rather than a direct fault with the fuel temperature sensor itself.

• Tier 4 Ecomax engines

1. 1

   Visually inspect the wiring harness and connectors between the fuel temperature sensor (often located on the high-pressure fuel pump) and the engine ECU for damage, chafing, corrosion, cracked insulation, loose pins, or water ingress from pressure washing.

2. 2

   Use a diagnostic scanner to check for any other active or stored fault codes that could provide clues to the root cause.

3. 3

   Disconnect the battery and measure CAN bus termination resistance between CAN High and CAN Low at a diagnostic port (should be approximately 60 Ohms; 120 Ohms indicates an open circuit, 0 Ohms indicates a short).

4. 4

   Check for shorts to ground by measuring resistance between each CAN wire and chassis ground (should be megaohms).

5. 5

   Check for shorts to power by measuring DC voltage between each CAN line and chassis ground with the system powered on and the bus asleep (there should be no significant voltage).

1. 1

   Repair wiring and connectors

   If the initial visual inspection reveals damaged wiring or corroded connectors, repair or replace these components. Clean any corroded contacts with electrical contact cleaner, ensure all connections are secure, clear the fault codes, and re-test.

2. 2

   Isolate faulty CAN module

   If CAN bus resistance and voltage checks indicate a network problem, disconnect modules on the CAN network one by one, re-measuring the bus resistance after each disconnection. If disconnecting a specific module causes the resistance to return to normal, that module is likely the source of the fault.

3. 3

   Test sensor circuit

   With a multimeter, check for the correct voltage supply to the fuel temperature sensor and for continuity on the signal wire back to the ECU. Measure the resistance of the fuel temperature sensor itself and compare it to the manufacturer's specifications.

4. 4

   Diagnose Engine ECU

   If the wiring and sensor are confirmed to be in good condition, the fault may lie within the Engine ECU failing to process or transmit the message. Use a dealer-level diagnostic tool (JCB Electronic Service Tool) to perform communication tests. Test with a known good unit to definitively confirm an ECU fault.