Eaton Fuller Hybrid Transmission Fault Code 95 – 12-Volt Cranking Relay
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. Read below to learn how to test, clear and fix fault code errors for your Freightliner, Mack, Peterbilt, Kenworth, Volvo, International, and heavy-duty truck and equipment.
The 12-volt Cranking Relay is wired into the Hybrid Control Module (HCM) on the coil side of the relay. At key on, the HCM determines which starting method to use either High-Voltage Motor/Generator, or Engine Starter.
If the HCM uses the Motor/Generator to start the engine, the clutch is closed, the 12-Volt Cranking Relay is de-energized, which disconnects the main battery power supply to the Start Enable Relay. If the HCM uses the standard engine starter, the 12-Volt Cranking Relay is energized supplying battery power to the Start Enable Relay main feed, which then powers the Starter Solenoid.
Fault Code 95 – 12-Volt Cranking Relay Detection
The following preconditions must be met before the system detects the fault:
- Hybrid Control Module (HCM) ignition voltage is greater than 7 volts and less than 16 volts.
- Engine speed is 0 RPM or unknown.
Note: When troubleshooting an Inactive code refer to the Product Diagnostic Mode (PDM)
Conditions to Set Fault Code Active
- FMI 3 if the HCM detects am open or short to VBATT in the control circuit of the 12-Volt Cranking Relay for 1 second or greater.
- FMI 4 is set if the HCM detects a short to ground in the control circuit of the 12-Volt Cranking Relay for 1 second or greater.
Fallback When Fault Code 95 is set the following conditions occur:
- Amber “Check Hybrid” light illuminates.
- Fault is stored in Hybrid Control Module (HCM) memory.
- If the fault sets at power up, the engine will crank, provided the high-voltage batteries have a sufficient State of Charge (SOC).
- If the fault sets while driving, the vehicle will continue to operate.
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:
- FMI3, 4
- Vehicle Harness from HCM to 12-volt Cranking Relay
- 12-volt Cranking Relay
Fault Code 95 – 12-Volt Cranking Relay Test
Harness Front View
(HCM – Hybrid System Interface Connector)
Typical Relay Switch
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.