Eaton Fuller Hybrid Fault Code 24 – J1939 HCM Message (TECU)
Fault code for Eaton Hybrid Drive Systems models (MY08) EH-8E306A-U, EH-8E306A-UPG, EH-8E306A-UP, EH-8E306A-CD, EH-8E306A-T, EH-6E606B-CD, (MY09) EH-8E406A-U/P, EH-8E406A-UP, EH-8E406A-UPG, EH-8E406A-CD, EH-8E406A-CDG, EH-8E406A-CDR, EH-8E406A-T, EH-6E706B-CD, EH-6E706B-P and EH-6E706B-UPG. The Transmission Electronic Control Unit (TECU) communicates with the Hybrid Control Module (HCM) over the J1939 data link during vehicle operation to exchange requested gear and current gear information.
Fault Code 24 – J1939 HCM Message (TECU) Detection
The following preconditions must be met before the system detects the fault:
- TECU ignition voltage is greater than 7 volts and less than 16 volts.
- No J1939 data link fault currently Active in the TECU.
Conditions to Set Fault Code Active
- FMI 9 is set when the TECU fails to receive transmission data (such as a requested gear) for 2 seconds or greater from the HCM, and it is still communicating with other modules on J1939.
Fallback When Fault Code 24 is set the following conditions occur:
- Red “Service” light illuminates, and an “F” flashes in the gear display.
- Fault is stored in TECU memory.
- Operation mode changes to AutoShift Fallback mode.
- If the fault sets at power up, the engine does not crank.
- If the fault sets while driving, the vehicle remains in current gear. When the vehicle stops the clutch opens and remains in this position.
- Amber “Check Hybrid” light may display on the dash due to an Active Fault Code 48.
Conditions to Set Fault Code Inactive
Only Inactive faults can be cleared from the TECU or HCM history using ServiceRanger. The TECU automatically clears faults from history after 200 hours. The HCM automatically clears a fault from history after it has been Inactive for 200 hours.
This fault code can be caused by any of the following:
- FMI 9
- J1939 Data Link
Fault Code 24 – J1939 HCM Message (TECU) Test
Component Identification MY08 System:
Harness Front View
TECU – Vehicle Interface Connector
Harness Front View
(HCM – Vehicle Interface Connector)
NOTE: Refer to the Eaton Hybrid Component and Connector Location for Connector Locations in MY08 Systems
NOTE: Refer to the Eaton Hybrid Component and Connector Location for Connector Locations in MY09 Systems.