P0AFA

DTC P0AFA

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (with HP2) (Initial Inspection and Diagnostic Overview)Diagnostic System Check - Vehicle (without HP2) (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 Descriptor
DTC P0AFA
- Hybrid Battery System Voltage Low -ACCM 300V

Diagnostic Fault Information





Typical Scan Tool Data









Circuit/System Description

The air conditioner control module (ACCM) monitors the high voltage direct current (HVDC) voltage to ensure that the voltage stays within the proper range. Damage to components, and incorrect data may occur when the voltage is out of range. If the ACCM detects low HVDC voltage, then DTC P0AFA will set.

Conditions for Running the DTC

* The engine is running or is in autostop mode.
* The 12V system voltage is between 9.5-18 volts.

Conditions for Setting the DTC

The ACCM detects that the hybrid battery voltage is less than 215 volts for 0.5 seconds.

Action Taken When the DTC Sets

The air conditioning is disabled.

Conditions for Clearing the DTC

* The DTC will pass when the ACCM detects a hybrid battery voltage greater than 225 volts.
* A history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.

Reference Information
Schematic Reference

* HVAC Schematics (HVAC - Automatic)
* Hybrid Controls Schematics (Electrical Diagrams)

Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

* Heating and Air Conditioning System Description and Operation (HP2) (Heating and Air Conditioning System Description and Operation)
* High Voltage Monitoring Systems Description (High Voltage Monitoring Systems Description)

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
Special Tools

EL-48900 HEV Safety Kit

Circuit/System Verification

1. Verify that no hybrid powertrain control module (HPCM) or engine control module (ECM) DTCs are set that indicate generator, HPCM, or battery failure, or that disable the high voltage.

• If the specified DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code Descriptions).

2. Engine cranking, observe the scan tool accessory DC power control module (APM) HPCM 300V Circuit parameter. The reading should be between 225 Volts and 380 Volts.

• If not within the specified range, refer to Jump Assist (Hybrid Energy Storage).

3. Ignition ON, observe the scan tool ACCM High Battery Voltage parameter. The reading should be between 225 Volts and 380 Volts.

Circuit/System Testing

Danger: Always perform the High Voltage Disabling procedure prior to servicing any High Voltage component or connection. Personal Protection Equipment (PPE) and proper procedures must be followed.


The High Voltage Disabling procedure will perform the following tasks:


* Identify how to disable high voltage.

* Identify how to test for the presence of high voltage.

* Identify condition under which high voltage is always present and personal protection equipment (PPE) and proper procedures must be followed.


Failure to follow the procedures exactly as written may result in serious injury or death.


1. Disable the high voltage, and remove the 3 phase cable cover. Refer to High Voltage Disabling (High Voltage Disabling).
2. Ignition OFF, verify that the air conditioner compressor HVDC terminal bolts are present and are torqued to specification.

• If the bolts are missing or are not tight, replace any damaged components, install and tighten the bolts.

3. If all circuits test normal, replace the ACCM.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

Control Module References (Programming and Relearning) for ACCM replacement, setup, and programming