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 Hybrid Control Module (HCM) is mounted to the transmission and contains all of the software to control both the hybrid power electronics as well as the transmission operation. The HCM ignition power is a fused, single 12-volt feed that runs through the HCM 38-Way Vehicle Connector.
Fault Code 8 – Loss of Switched Ignition Power (HCM) Detection
The following preconditions must be met before the system detects the fault:
- Output Shaft speed must be greater than 0 RPM.
Conditions to Set Fault Code Active
Conditions to Set Fault Code:
• FMI 4 is set when the HCM loses ignition power during operation for 2 seconds or greater.
Fallback When Fault Code 8 is set the following conditions occur:
- Amber “Check Hybrid” light illuminates.
- Fault is stored in Hybrid Control Module (HCM) memory.
- Red “Service” light illuminates and an “F” flashes in the gear display, if the fault occurs prior to power up.
- Fault is stored in Transmission Electronic Control Unit (TECU) memory due to lack of communication with the HCM.
- If fault occurs while the vehicle is moving, the transmission remains in place and the clutch opens when the vehicle comes to an idle. The clutch closes and the vehicle will operate in 1st and reverse from stop.
- If this fault occurs at power up, the vehicle does not crank.
Conditions to Set Fault Code Inactive
Only Inactive faults can be cleared from the Transmission Electronic Control Unit (TECU) or HCM history using ServiceRanger. The TECU automatically clears the faults from history after 200 hours and the HCM automatically clears the faults from history after the fault has been Inactive for 200 hours.
This fault code can be caused by any of the following:
- FMI 4
- Ignition Power Supply to HCM