Fault Code 88 - InverterCAN Message Fault (HCM)

The Inverter communicates with the Battery Control Unit (BCU) located in the Power Electronics Carrier (PEC) and the Hybrid Control Module (HCM) on the Controller Area Network (CAN) high-speed proprietary data link. The data link is a two wire twisted pair with two 120 ohm resistors located in the link. Fault Code 88 will only be set with Hybrid Control Module (HCM) software level 663 and lower. HCM software 671 and greater will set a fault code 111 for the inverter CAN message fault.

Fault is detected when:

• HCM ignition voltage is greater than 7 volts and less than 16 volts.

• HCM CAN Data Link fault is not Active.

The following conditions may set the fault Active:

• FMI 9 is set when the HCM has not received a Inverter message for 30 consecutive message cycles.

• FMI 2 is only Active in Product Diagnostic Mode (PDM) and sets if 3 consecutive Inverter messages are not received by the HCM.

When Fault Code 88 is set the following conditions occur:

• Amber “Check Hybrid” light illuminates.

• Fault is stored in HCM memory.

• Electric Motor/Generator Assist and Regeneration are disabled; however, the high-voltage relays will remain powered.

• HCM continues to control the hybrid vehicle in a diesel-only mode.

• Transmission defaults start gear to 1st.

This fault code can be caused by any of the following:

• FMI 9, 2:

- CAN Data Link

- No power or ground to Inverter

- HCM

- Inverter

Only inactive faults can be cleared from the TECU or HCM history using ServiceRanger. The TECU will automatically clear the faults from history after 200 hours and the HCM will automatically clear the faults from history after 200 hours of the fault staying inactive.

• Basic Hand Tools

• Eaton Test Adapter Kit

• Digital Volt/Ohm Meter

• Service Ranger

1. Retrieve Active fault codes and FMIs with ServiceRanger using the 9-Way Diagnostic Connector.

2. Perform the Electrical Pretest on page 24 and the Hybrid Electrical Pretest on page 28.

• If no issues are found during the Hybrid Electrical Pretest, go to Step B.

• If issue was repaired during the Hybrid Electrical Pretest, go to Step V.

1. Key off.

2. Disconnect Inverter 40-Way Connector.

3. Measure resistance between Inverter 40-Way connector Pin 5 and Pin 4.

• If resistance is OL or outside 50–70 ohms, repair OEM CAN link harness. go to Step V.

• If resistance is between 50–70 ohms, go to Step C.

Measure CAN to ground resistance on Inverter OEM connector:

- Pin 1 to Inverter case

- Pin 2 to Inverter case

• If either resistance is 0–100 ohms, repair shorted CAN link circuit. go to Step V.

• If both resistances are 7k ohms, go to Step D.

1. Measure resistance between Inverter 40-Way Pin 4 and Dash 9-Way Diagnosis Connector Pin H. (If Pin H is not populated, find 3-Way Connector near

9- Way or terminating resistor Pin 1 near 9-Way.)

• If resistance is 0–0.3 ohms, go to Step E.

• If resistance is 60 ohms, repair CAN wiring (hi and low are wired wrong). go to Step V.

1. Key on, with Inverter 40-Way still disconnected.

2. Measure voltage on 40-Way connector:

- Pin 1 to Pin 6

3. Measure voltage on 40-Way connector:

- Pin 2 to Pin 7

• If battery voltage (12 V +/- 1.2 V) is present, replace Inverter. go to Step V.

• If battery voltage is not present or less than 1.2 V of battery voltage, go to Step F.

Measure resistance between Inverter 40-Way Connector Pin 6 and ground or Inverter 40-Way Connector Pin 7 and ground

• If resistance is 0–0.3 ohms, go to Step G.

• If resistance is greater than 0.3 ohms, repair OEM ground circuit to Inverter. go to Step V.

1. Key off.

2. Remove 38-Way Hybrid Vehicle Interface Connector.

3. Measure resistance on 38-Way Hybrid Vehicle Interface Connector (S2) Pin 2 to Inverter 40-Way Pin 1.

• If resistance is 0–0.3 ohms, replace HCM. go to Step V.

• If resistance is OL or greater than 0.3 ohms, repair OEM harness between HCM and Inverter. go to Step V.

1. Key off.

2. Reconnect all connectors.

3. Key on.

4. Clear codes. See “Fault Code Retrieval and Clearing” on page 13.

5. Drive the vehicle and attempt to recreate the code.

6. Check for codes. See “Fault Code Retrieval and Clearing” on page 13.

• If no codes, test is complete.

• If Fault Code 88 appears, find error in testing, go to Step A.

• If a code other than 88 appears, go to “Fault Code Isolation Procedure Index” on page 14/