P0AF8

The engine control module (ECM) monitors the correlation of the battery energy control module (BECM) battery voltage and the starter generator control module (SGCM) output voltage to detect a 36 volt cable open or fuse/relay failure.

P0AFB

The ECM also monitors to detect an over voltage condition and protect the MOSFET (load dump).

If either one of these conditions is detected, the appropriate DTC will set.

The engine is running.

P0AF8

The 36 volt BECM battery voltage - 36 volt SGCM output voltage is greater than 5 volts for 4 seconds.

P0AFB

P0AF8, P0AFB

P0AF8

36-volt voltage from BECM (42 VIN) is greater than 0 volt, main relay is closed, and 42 VIN invalid flag is ON.

P0AFB

P0AF8

P0AFB

Schematic Reference

Connector End View Reference

Component Connector End Views

Electrical Information Reference

Scan Tool Reference

Control Module References

Caution: To help avoid personal injury, additional precautions must be taken prior to working on the generator control module or the generator starter. After removing the 36V battery cables from the generator battery, remove both engine wiring harness connectors from the generator control module. Wait at least 5 minutes and then remove the generator control module cover. Verify voltage levels at all 36V, 12V, and 3-phase connections, are less than 3 volts using a DMM before proceeding.

Caution: To help avoid personal injury, be careful when working in the vicinity of the generator battery disconnect control module. Internal components will still be live, 36V potential, even when the cover has been opened or removed.

P0AF8

1. If DTC is history, refer to Testing for Intermittent Conditions and Poor Connections .
2. Ignition ON, observe the scan tool Hybrid Battery System Voltage parameter in the BECM data list and the Hybrid System Voltage parameter in the SGCM data list. The voltage should not differ by more than 5 volts.

⇒	If greater than the specified value, continue with Circuit/System Testing.

P0AFB

1. If DTC is history, refer to Testing for Intermittent Conditions and Poor Connections .
2. Ignition ON, observe the scan tool Hybrid Battery System Voltage parameter in the BECM data list. The voltage should be less than 50 volts.

⇒	If greater than the specified value , replace the SGCM.

P0AF8

1. Verify the DTC is set as current.
2. Ensure the hood is fully closed. Ignition ON, observe and record the scan tool Hybrid Battery System Voltage parameter in the SGCM data list.
3. Open the hood. Gain access to the 36 volt output cable connection at the SGCM refer to Generator Control Module Cover Replacement
4. Measure the voltage at the 36 volt output cable connection at the SGCM to ground, the voltage should not differ by more than 3 volts than the scan tool parameter recorded in step 2.

⇒	If greater than the specified value replace the SGCM.

5. Ignition ON, observe and record the scan tool Hybrid Battery System Voltage parameter in the BECM data list.
6. Ignition OFF, remove the Hybrid Battery Pack service cover refer to Hybrid Battery Service Disconnect/Connect Inspect the 36  volt and ground cable connections of the Hybrid Battery Pack.
7. Depress and hold the service disconnect for 20 seconds and measure the voltage at the Hybrid Battery Pack the 36  volt terminal to ground. The voltage should not differ by more than 3 volts from the voltage measured in step 4.

⇒	If greater than the specified value, test the 36  volt cable for short to ground or an open/high resistance.

8. Note some vehicles have a plastic cover over this area to be measured that must be removed. Measure the voltage at the Hybrid Battery Pack the 36  volt terminal pack side of contactor to ground. The voltage should not differ by more than 3 volts from the scan tool parameter display in step 5.

⇒	If greater than specified value inspect the Hybrid Battery Pack ground cable for an open/high resistance or the Hybrid Battery Pack fuse for an open.

9. If the ground circuit tests normal, the fuse was not open and voltage differs by more than 3 volts. Replace the BECM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.