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HVAC - Automatic




DTC P0AF8

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructionsprovides an overview of each diagnostic category.

DTC Descriptor
DTC P0AF8 03
- Hybrid System Voltage

Circuit/System Description

The coolant heater control module will determine when a fault condition is present. Diagnostics and system status are communicated from the coolant heater control module to hybrid powertrain control module 2 through serial data.

Conditions for Running the DTC

Propulsion system is active.

Conditions for Setting the DTC

The coolant heater control module has detected less than 100 V on the high voltage bus for more than 5 seconds.

Action Taken When the DTC Sets

* DTC P0AF8 is a type A DTC.
* No cabin heat after 15 seconds.

Conditions for Clearing the DTC

DTC P0AF8 is a type A DTC.

Diagnostic Aids

Do not replace the coolant heater control module based only on DTC P0AF8 being set in history. P0AF8 may be set by disconnecting the high voltage cables to the coolant heater control module and the ignition is turned ON.

Reference Information
Schematic Reference

HVAC Schematics
Connector End View Reference

Component Connector End Views Hybrid/EV Battery Pack X1 A4
Description and Operation

Automatic HVAC Description and Operation
Electrical Information Reference

* Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference

Control Module References Control Module Referencesfor scan tool information
Special Tools

EL-48900 - HEV Safety Kit

For equivalent regional tools, refer to Special Tools Tools and Equipment.

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.


Before working on any high voltage system, be sure to wear the following Personal Protection Equipment:


* Safety glasses with appropriate side shields when within 15.24 meters (50 feet) of the vehicle, either indoors or outdoors.

* Certified and up-to-date Class "0" Insulation gloves rated at 1000V with leather protectors.


- Visually and functionally inspect the gloves before use.

- Wear the Insulation gloves at all times when working with the high voltage battery assembly, whether the system is energized or not.


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


Danger: The Volt Battery Pack will utilize an exchange program. Please consult the most recent revision of bulletin/PI #PIP4841, available in Service Information (SI), for a list of approved Volt Battery Pack service procedures. Components that may be removed and serviced without exchanging the complete battery pack are identified in the bulletin/PI. Please contact the GM Technical Assistance Center (1-877-446-8227) if you have any questions.


1. Verify that P0AF8 is current and no other DTCs are set.

• If P0AF8 is history, Do not replace the coolant heater control module.
• If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .

2. P0AF8 is current, Vehicle OFF, disable the high voltage at the K10 coolant heater control module. Refer to High Voltage Disabling High Voltage Disabling.
3. Test for less than 10 ohm between the terminals listed below:

* High voltage DC (-360 V) negative terminal B X4 harness connector at the K114A hybrid powertrain control module 1 to vehicle chassis ground.
* High voltage DC (+360 V) positive terminal A X4 harness connector at the K114A hybrid powertrain control module 1 to vehicle chassis ground.
* High voltage DC (+360 V) positive terminal A X4 harness connector at the K114A hybrid powertrain control module 1 and the high voltage DC (-360 V) negative terminal B X4 harness connector at the K114A hybrid powertrain control module 1.
* High voltage DC (-360 V) negative terminal B X2 harness connector at the K10 coolant heater control module and the high voltage DC (-360 V) negative terminal B X4 harness connector at the K114A hybrid powertrain control module 1.
* High voltage DC (+360 V) positive terminal A X2 harness connector at the K10 coolant heater control module and the high voltage DC (+360 V) negative terminal A X4 harness connector at the K114A hybrid powertrain control module 1.

• If greater than the specified range, replace the replace the high voltage DC cables.

4. If all circuits test normal, and the high voltage DC-360 V circuit fuse is open, replace the K10 coolant heater control module.

Repair Instructions

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

* 300-Volt Battery Positive and Negative Cable Replacement 300-Volt Battery Positive and Negative Cable Replacement (Drive Motor Battery-to-Inverter )
* Control Module References Control Module Referencesfor coolant heater control module replacement, programming and setup

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