Diagnostic Instructions
DTC Descriptors
DTC P0AFA: Hybrid Battery System Voltage Low
Circuit/System Description
The starter generator control module (SGCM) monitors the hybrid battery voltage to verify that the output voltage (36 volts) Is within normal operating value (above 22 volts). If the output voltage is not within this value, this DTC will
set.
Conditions for Running the DTC
The engine is running.
Conditions for Setting the DTC
36 volt output voltage is less than 22 volts for 2 seconds.
Action Taken When the DTC Sets
• | Stop PWM (MGU shutdown) |
Conditions for Clearing the DTC
36 volt output voltage increases to greater than 22 volts.
Diagnostic Aids
• | Possible battery cable open |
• | Possible fuse/relay block electrical failure |
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
Scan Tool Reference
Scan Tool Data List
Circuit/System Verification
- Ignition ON, observe the scan tool Hybrid System Voltage parameter in the SGCM data list. The voltage should be greater than 22 volts. If the parameter displays less than the specified value, refer to SGCM 36 volt Output Terminal Circuit
Low.
- Ignition ON, observe the scan tool Hybrid System Voltage parameter in the BECM data list. The voltage should be greater than 22 volts. If the parameter displays less than the specified value, refer to Battery Pack Voltage Low.
Circuit/System Testing
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.
SGCM 36 volt Output Terminal Circuit Low
- If DTC is history, refer to
Testing for Intermittent Conditions and Poor Connections .
- Ignition ON, test for greater than 22 volts at the SGCM battery positive 36 volt output voltage stud.
⇒ | If less than the specified value, test the 36 volt cable for an open/high resistance or short to ground. |
⇒ | If greater than the specified value, replace the SGCM. |
Hybrid Battery Pack Voltage Low
- If DTC is history, refer to
Testing for Intermittent Conditions and Poor Connections .
- Gain access to the hybrid battery pack. Refer to
Hybrid Battery Service Disconnect/Connect.
- Ignition OFF, test battery pack voltage for greater than 22 volts.
⇒ | If less than the specified value, replace the battery pack. |
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.