Eaton Fuller Hybrid Fault Code 5 Motor Generator AC Cable
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 Motor/Generator AC Cables are connected from the Motor/Generator to the Inverter. These cables carry up to 500 volts AC 3 phase when the vehicle is in operation.
Fault Code 5 Motor/Generator AC Cable Detection
- Inverters ignition voltage is greater than 7 volts and less than 16 volts.
- FMI 25–27 require the Motor/Generator RPM to be greater than 500 RPM.
- FMI 28 requires the Motor/Generator RPM to be less than 500 RPM.
- FMI 29 requires the Motor/Generator RPM to be less than 50 RPM.
Conditions to Set Fault Code Active
Conditions to Set Fault Code:
- FMI 21: Set when the AC interlock circuit is open.
- FMI 22, 23, 24 are set when the 2-phase motor current is more than 360 amps for 0.9 MS.
- FMI 25, 26, 27 are set when the Inverter detects a single open wire and motor current is less than 8 amps for 200 MS at speeds greater than or equal to 500 RPM and current command from the Inverter is greater than 20 amps.
- FMI 28 is set when Motor/Generator current is less than 8 amps for 200 MS at speed less than 500 RPM and current command is greater than 20 amps.
- FMI 29 is set during initialization. The Inverter determines if the AC Cable is connected between the motor and Inverter by sending out 20 amps for 200 MS and checking the feedback.
Fallback When Fault Code 5 is set the following conditions occur:
- Red “Stop Hybrid” light illuminates.
- Fault is stored in Hybrid Control Module (HCM) memory.
- Inverter shuts high-voltage system off.
- HCM continues to control the hybrid vehicle in a diesel-only mode.
- If FMI 28, or 29 is present 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. The HCM automatically clears the faults from history after the fault code has been Inactive for 200 hours.
This fault code can be caused by any of the following:
- FMI 21
- AC Cable Interlock
- FMI 22, 23, 24
- Inverter
- Motor/Generator
- AC cable
- FMI 25, 26, 27, 28, 29
- Motor/Generator
- AC Cable
Fault Code 5 – Motor/Generator AC Cable Test
Component Identification MY08 System:

High-Voltage AC Harness Connector View
(Amphenol Connector)

High-Voltage AC Motor/Gen Connector View
(Amphenol Connector)
NOTE: Refer to the Eaton Hybrid Component and Connector Location for Connector Locations in MY08 Systems

Component Identification MY09 System:

High-Voltage AC Harness Connector View
(Amphenol Connector)

High-Voltage AC Motor/Gen Connector View
(Amphenol Connector)
NOTE: Refer to the Eaton Hybrid Component and Connector Location for Connector Locations in MY09 Systems.

Warnings & Cautions
Danger: Danger indicates you will be severely injured or killed if do not follow the indicated procedure.
Warning: Warning indicates an immediate hazard, which could result in severe personal injury if you do not follow the indicated procedure.
Caution: Caution indicates vehicle or property damage could occur if you do not follow the indicated procedure.
Note: Note indicates additional detail that will aid in the diagnosis or repair of a component/system.
Follow the specified procedures in the indicated order to avoid personal injury:
1. If the high-voltage cones are around the vehicle and the lockout is installed on the PEC, the only person that should be allowed to start the vehicle is the person who signed the lockout tag.
2. Before working on a vehicle or leaving the cab while the engine is running, you should place the shift lever in “N” set the parking brake, and block the wheels.
3. For safety reasons, always engage the service brakes prior to selecting gear positions from “N.”
4. Before starting a vehicle always be seated in the driver’s seat, select “N” on the shift control, and set the parking brakes.
5. In vehicles with ePTO, the engine and/or
Motor/Generator can start in ePTO mode. Never perform any maintenance or work on vehicle, while in this mode.
6. 12-Volt Battery positive (+) and negative (-) must be disconnected prior to any welding on any Hybrid equipped vehicle.
Caution: Follow the specified procedures in the indicated order to avoid equipment malfunction or damage.
Caution: Do not release the parking brake or attempt to select a gear until the air pressure is at the correct level.
Caution: To avoid damage to the transmission during towing place the shift lever in “N” and lift the drive wheels off the ground or disconnect the driveline.
High-Voltage Warnings & Cautions
- Use CO2 or Dry Chemical Fire Extinguishers.
- The high-voltage wiring is covered in orange insulation or convoluted tubing and marked with warning labels at the connectors.
- All Eaton® Hybrid Diesel/Electric vehicles will be marked ‘Hybrid’ on the outside of the vehicle, along with the shift label on the dash.
- Refer to OEM for specific location of chassis mounted hybrid components.
- Do NOT cut into the orange high-voltage cables.
- Do NOT cut into or open the PEC.
- Do NOT cut into or open the DC/DC Converter.
- Do NOT cut into or open the Inverter.
A buffer zone must be set up and high-voltage insulated rubber gloves (class 0 with leather protectors) are required prior to working on high-voltage. Failure to follow these instructions may result in severe personal injury or death.
The rubber-insulated gloves that must be worn while working on the high-voltage system are class 0 with leather protectors. The rubber gloves should be tested before EVERY use following the rubber insulation gloves testing procedure found in “Diagnostic Tools/Service Publications” on page 6. Failure to follow these instructions may result in severe personal injury or death.
Before inspecting or working on any high-voltage cables or components the “High-Voltage Service Shutdown and Power-Up Procedure” on page 4 should be followed. Failure to follow these instructions may result in severe personal injury or death.
The Lockout and Tagout devices should only be removed by the technician that placed the Lockout and Tagout devices on the vehicle. Failure to follow these instructions may result in severe personal injury or death.
High-voltage rubber insulated gloves (class 0 with leather protectors) must be worn when working on any
high-voltage cables. The “High-Voltage Service Shutdown and Power-Up Procedure” on page 4 must be followed prior to removing any high-voltage cables. Failure to follow these instructions may result in severe personal injury or death.
High-voltage cables and wiring are orange and contain a warning label at the connectors. High-voltage components are marked with a label. High-voltage rubber insulated gloves (class 0 with leather protectors) must be used when working on any of these components. Failure to follow these instructions may result in severe personal injury or death.
High-Voltage Service Shutdown Procedures
1. Follow “High-Voltage Work Area” procedure.
2. Locate the red PEC Service Switch on the front of the PEC and push switch off.
3. Remove the Service Switch Cover and install the Lockout Bracket (J48506).
4. Fasten tag to the Lockout Bracket.
5. Ensure the PEC Service Switch can not move from the off position.
6. Allow the system to set for a minimum of 5 minutes to discharge high voltage.
7. Connect ServiceRanger and view the Data Monitor PID 116 called “High-Voltage Battery Potential.” Use SPN 520323 for J1939 connection “Battery Voltage RB” (Relay Box).
8. The voltage should be 30 volts or less. If the voltage is above 30 volts, do not work on the vehicle and contact Eaton® at 1-800-826-HELP (4357).
9. Turn ignition key off and proceed to repair or troubleshooting step.
Note: The voltage drops to zero when the key is off.
High-Voltage Service Power-Up Procedure
1. Install all high-voltage connectors into their locked positions.
2. If you are the person working on the vehicle, remove the Lockout Bracket and tag.
3. Reinstall the Lockout Bracket over the Service Switch.
4. Pull the Service Switch out and let vehicle set for 2 minutes.
5. Start vehicle when appropriate.
Eaton Hybrid Component and Connector Location

Eaton Hybrid Component and Connector Location MY09 Systems

STEP 1. Check for Active or Inactive fault code status.
- Review and follow the Warnings & Cautions.
- Retrieve Active fault codes and FMIs with ServiceRanger using the 9-Way Diagnostic Connector.
- Key off.
Warning: See High-Voltage Service Shutdown and Power-Up Procedures. Follow the procedures to avoid shock, burn or death from improperly handled high-voltage. - Which faults are present?
- If Fault Code 5 FMI 21 is Active, go to Step 5
- If Fault Code 5 FMI 22, 23, or 24 are Active, go to Step 2.
- If Fault Code 5 FMI 25, 26, 27, 28, or 29 are Active, go to Step 3.
STEP 2. Verify continuity of high-voltage cable.
- Key off.
- Remove the AC high-voltage cable at the Motor/Generator and Inverter
- Measure the resistance between the following AC cable pins:
-
- (MY08 Only)
-
- Pin A to Pin B
- Pin B to Pin C
- Pin C to Pin A
(MY09 Only)
-
- Pin C to Pin B
- Pin B to Pin A
- Pin A to Pin C
-
- If resistance between each phase is 5M ohms or greater, replace the Inverter, then go to Step 5 (MY08) Step 7 (MY09).
- If resistance is outside of range, replace the AC high-voltage cable, then go to Step 5 (MY08) Step 7 (MY09).
- (MY08 Only)
-
STEP 3. Verify continuity of high-voltage cable.
- Disconnect the AC high-voltage cable from the Inverter and Motor/Generator.
- Measure the resistance of the AC High-Voltage Cable from the Inverter Connector to the Motor/Generator Connector on each of the following pins:
-
-
- Pin A to Pin A
- Pin B to Pin B
- Pin C to Pin C
Note: An auto-ranging digital Volt/Ohm Meter must be used.
-
- If the resistance of each circuit is 1 ohm or less, go to Step 4
- If resistance is outside of range, replace the AC High-Voltage Cable, then go to Step 5 (MY08) Step 7 (MY09).
-
STEP 4. Verify continuity of high-voltage cable.
-
- Measure the resistance of each Motor/Generator phase at the following pins:
-
- (MY08 Only)
-
- Pin A to Pin B
- Pin B to Pin C
- Pin C to Pin A
(MY09 Only)
-
- Pin C to Pin B
- Pin B to Pin A
- Pin A to Pin C
Note: An auto-ranging digital Volt/Ohm Meter must be used.
-
- If the resistance of each phase is 10 ohms or less, replace the Inverter, then go to Step 5 (MY08) Step 7 (MY09).
- If resistance is outside of range, replace the Motor/Generator, then go to Step 5(MY08) Step 7 (MY09).
- (MY08 Only)
-
- Measure the resistance of each Motor/Generator phase at the following pins:
STEP 5. (MY08 Only) Verify repair.
- Key off
- Reconnect all connectors and the negative battery cable.
- Key on
- Clear codes
- Drive the vehicle and attempt to reset the code.
- Check for codes. If no codes, test is complete.
- If Fault Code 1 appears, find error in testing, go to Step 1.
- If a new code appears, see Fault Code Index List.
STEP 5. (MY09 Only) Verify continuity of high-voltage cable.
- Check the AC Cable Connectors at the motor/generator and Inverter to ensure they are properly connected:
- If connections are loose or not properly connected, reconnect AC Cables to component and go to Step 7.
- If connections are not loose and are properly connected, go to Step 6.
STEP 6. (MY09 Only) Verify continuity of high-voltage cable.
-
- Disconnect the AC cable from the motor/generator and Inverter.
- Measure the interlock circuit resistance from the Inverter Connector and the Motor/Generator Connector at the following pins:
- Pin D and Pin D
- Pin E and Pin E
Note: An auto-ranging digital volt/ohm meter must be used
- If the resistance is 0–0.3 ohms, replace the Inverter. See the MY09 Inverter Removal and Installation procedure in TRSM2000, go to Step 7.
- f resistance is outside of range, replace the AC cable between the Inverter and Motor/Generator, then go to Step 7.
STEP 7. (MY09 Only) Verify repair.
- Key off
- Reconnect all connectors and the negative battery cable.
- Key on
- Clear codes
- Drive the vehicle and attempt to reset the code.
- Check for codes. If no codes, test is complete.
- If Fault Code 1 appears, find error in testing, go to Step 1.
- If a new code appears, see Fault Code Index List.
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