Eaton Fuller Hybrid Transmission Fault Code 118 – Auxiliary High Voltage Relay Control Circuit Fault
Fault code for Eaton Hybrid Drive Systems models (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 auxiliary high-voltage relays, located in the Power Electric Carrier (PEC), are controlled by the Hybrid Control Module (HCM). At key on, high-voltage power is supplied from the Relay Box to the auxiliary high-voltage relays. When the ePTO option is selected on the Push Button Shift Control, the HCM energizes the control circuits for the main positive and main negative relays. The power then flows through the auxiliary high-voltage relays to the DC/DC Converter.
Fault Code 118 – Auxiliary High Voltage Relay Control Circuit Fault 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.
Note: When troubleshooting an Inactive code refer to the Product Diagnostic Mode (PDM)
Conditions to Set Fault Code Active
- FMI 3 is set when the HCM detects a short to battery in the coil circuit of the auxiliary high-voltage relay.
- FMI 4 is set when the HCM detects a short to ground in the coil circuit of the auxiliary high-voltage relay.
- FMI 5 is set when the HCM detects an open in the coil circuit of the auxiliary high-voltage relay.
Fallback When Fault Code 118 is set the following conditions occur:
- Amber “Check Hybrid” light illuminates.
- Fault is stored in Hybrid Control Module (HCM) memory.
- The DC/DC Converter does not operate because the HCM de-energizes the auxiliary high-voltage relay circuit.
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 3, 4, 5
- OEM wiring from HCM to PEC
- DC/DC cable high-voltage loop
- DC/DC converter
- Auxiliary Power Generator (APG) cable high-voltage loop (if equipped)
- APG converter (if equipped)
- Auxiliary high-voltage relay (inside PEC)
Fault Code 118 – Auxiliary High Voltage Relay Control Circuit Fault Test
NOTE: Refer to the Eaton Hybrid Component and Connector Location for Connector Locations in MY09 Systems.
If vehicle is not equipped with APG, a HV interlock cap with loop should be installed if vehicle is not equipped with a DC/DC, A HV Interlock cap with loop should be installed.