P0AFA

DTC P0AFA

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.

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)
* APM PWM off

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

* Hybrid Controls Schematics (Electrical Diagrams)
* Hybrid Energy Storage Schematics (Electrical Diagrams)

Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Starter/Generator Description and Operation (Description and Operation)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Verification

1. 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.
2. 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 Hybrid Battery Pack Voltage Low.

Circuit/System Testing

SGCM 36 volt Output Terminal Circuit Low
1. If DTC is history, refer to Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics).
2. 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
1. If DTC is history, refer to Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics).
2. Gain access to the hybrid battery pack. Refer to Hybrid Battery Service Disconnect/Connect (Procedures).
3. 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 (Verification Tests) after completing the diagnostic procedure.

* Generator Battery Replacement (Generator Battery Replacement)
* Control Module References (Programming and Relearning) for SGCM replacement, setup, and programming