P0AF8
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 Instructions provides an overview of each diagnostic category.
DTC Descriptor
DTC P0AF8
- Hybrid System Voltage
Circuit/System Description
The drive motor battery contains 288 cells. Groups of three cells are welded together in parallel. There are a total of 96 cell groups in the drive motor battery assembly. These cell groups are electrically connected in series. Each individual cell group is rated at 3.7 V, for a nominal system voltage of 355 V direct current. The battery cells are also grouped together into three sections. The first 90 cells / 30 cell groups make up battery section one. This section is adjacent to the cowl and contains batteries 67 through 96. Battery section two is located behind section one. It is made up of 72 cells / 24 cell groups and contains batteries 43 through 66. The transverse battery section is section number three, it is made up of the remaining 126 cells / 42 cell groups and contains batteries 1 through 42. The three battery sections are individually serviceable components.
The battery energy control module monitors the voltage of the 96 battery cell groups through the four drive motor battery high voltage interface controllers. Voltage sense lines are attached to each individual cell group, and these sense lines terminate at a connector located on the top surface of the battery section. A serviceable voltage sense harness joins this connector to a drive motor battery high voltage interface control module, also located on the top surface of the battery section. The drive motor battery high voltage interface control module encodes the voltage reading and transmits it to the battery energy control module through the battery control harness. There is one drive motor battery high voltage interface control module located on battery sections one and two, and two drive motor battery high voltage interface control modules associated with battery section three. The drive motor battery high voltage interface control module, voltage sense harnesses, battery control harness and battery energy control module are all considered serviceable components.
The battery energy control module will determine when a fault condition is present. Diagnostics and system status are communicated from the battery energy control module to hybrid powertrain control module 2 through serial data. The hybrid powertrain control module 2 is the host controller for diagnostic trouble code information.
Conditions for Running the DTC
* The hybrid/EV battery main contactors are closed.
* None of the following DTCs are set; P0ABB, P0ABC, P0ABD, P1A07, P1AE8, P1AE9, P1AEA, P1AEB, P1AEC, P1AED, P1AE20 P1AE27, or P1E28.
OR
* The hybrid/EV battery main contactors are open.
* The charger contactors are closed.
* The multifunction contactor is closed.
* None of the following DTCs are set; P0ABB, P0ABC, P0ABD, P0D4E, P0D4F, P0D5C, P16C5, P1A07, P1EEB, P1EEC, or P1ECE.
Conditions for Setting the DTC
* The difference between the Hybrid/EV Battery pack voltage and the hybrid powertrain control module bus voltage is greater than 12 V.
OR
* The difference between the Hybrid/EV Battery pack voltage and the charger module's bus voltage is greater than 12 V.
Action Taken When the DTC Sets
DTC P0AF8 is a type A DTC.
Conditions for Clearing the DTC
* DTC P0AF8 is a type A DTC.
* The Clear Secured High Voltage DTCs Reading and Clearing Diagnostic Trouble Codes reset function must be performed to prevent resetting the DTC.
Diagnostic Aids
An open charger fuse may cause P0AF8 to set.
Reference Information
Schematic Reference
Hybrid Energy Storage Schematics Hybrid Energy Storage Schematics
Connector End View Reference
Component Connector End Views Hybrid/EV Battery Pack X1
Description and Operation
Drive Motor Battery System Description Drive Motor Battery System Description
Electrical Information Reference
* Circuit Testing 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 Programming and Relearning for scan tool information
Special Tools
EL-48900 - HEV Safety Kit
For equivalent regional tools, refer to Special Tools Tools and Equipment.
Circuit/System Verification
1. Verify that no other DTCs are set.
• If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle.
2. Clear the P0AF8 and perform the Clear Secured High Voltage DTCs reset function. Refer toClear Secured High Voltage DTCs Reading and Clearing Diagnostic Trouble Codes.
3. Put the vehicle into Charge Mode by plugging in the wall charger.
4. Observe the hybrid powertrain control module 2 Battery Charger High Output parameter and the hybrid/EV battery energy control module Hybrid Battery Pack Terminal 1 Voltage parameter. Each reading should be within 12 V of each other and DTC P0AF8 did not reset.
• If readings are not within 12 V of each other or the DTC is set, refer Battery Charger Bus Diagnostics.
• If readings are within 12 V of each other and the DTC is not set, refer Battery Main Bus Diagnostics.
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 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 with leather protectors 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.
Battery Charger Bus Diagnostics
1. Vehicle OFF, disable the high voltage at the T18 Battery Charger. Refer to High Voltage Disabling High Voltage Disabling.
2. Disconnect the X7 harness connector at the A28 hybrid/EV battery contactor assembly.
3. Disconnect the X5 harness connector at the A28 hybrid/EV battery contactor assembly.
4. Test for infinite resistance between the terminals listed below:
* High voltage DC (-360 V) negative terminal B X5 harness connector at the A28 hybrid/EV battery contactor assembly to vehicle chassis ground.
* High voltage DC (+360 V) positive terminal A X5 harness connector at the A28 hybrid/EV battery contactor assembly to vehicle chassis ground.
* High voltage DC (+360 V) positive terminal A X5 harness connector at the A28 hybrid/EV battery contactor assembly and the high voltage DC (-360 V) negative terminal B X5 harness connector at the A28 hybrid/EV battery contactor assembly.
• If less than the specified value, replace the high voltage DC cables. After the repair is complete with a scan tool, the Clear Secured High Voltage DTCs Reading and Clearing Diagnostic Trouble Codes reset function must be performed.
5. Test for less than 10 ohm between the terminals listed below:
* High voltage DC (-360 V) negative terminal B X4 harness connector at the T18 Battery Charger and the high voltage DC (-360 V) negative terminal B X5 harness connector at the A28 hybrid/EV battery contactor assembly.
* High voltage DC (+360 V) positive terminal A X4 harness connector at the T18 Battery Charger and the high voltage DC (+360 V) negative terminal A X5 harness connector at the A28 hybrid/EV battery contactor assembly.
• If greater than the specified value, replace the high voltage DC cables. After the repair is complete with a scan tool, the Clear Secured High Voltage DTCs Reading and Clearing Diagnostic Trouble Codes reset function must be performed.
6. If all circuits test normal, replace the T18 Battery Charger. If the DTC resets, replace the A4 hybrid/EV battery pack assembly.
Battery Main Bus Diagnostics
1. Vehicle OFF, disable the high voltage at the T6 Power Inverter Module Assembly. Refer to High Voltage Disabling High Voltage Disabling.
2. Disconnect the F118 hybrid battery pack connector jumper connector at the A28 hybrid/EV battery contactor assembly.
3. Disconnect the X3 harness connector at the A28 hybrid/EV battery contactor assembly.
4. Test for infinite resistance between the terminals listed below:
* High voltage DC (-360 V) negative terminal B X3 harness connector at the A28 hybrid/EV battery contactor assembly to vehicle chassis ground.
* High voltage DC (+360 V) positive terminal A X3 harness connector at the A28 hybrid/EV battery contactor assembly to vehicle chassis ground.
* High voltage DC (+360 V) positive terminal A X3 harness connector at the A28 hybrid/EV battery contactor assembly and the high voltage DC (-360 V) negative terminal B X3 harness connector at the A28 hybrid/EV battery contactor assembly.
• If less than the specified value, replace the high voltage DC cables. After the repair is complete with a scan tool, the Clear Secured High Voltage DTCs Reading and Clearing Diagnostic Trouble Codes reset function must be performed.
5. Test for less than 10 ohm between the terminals listed below:
* High voltage DC (-360 V) negative terminal B X3 harness connector at the A28 hybrid/EV battery contactor assembly and the high voltage DC (-360 V) negative terminal B X3 harness connector at the T6 Power Inverter Module Assembly.
* High voltage DC (+360 V) positive terminal A X3 harness connector at the A28 hybrid/EV battery contactor assembly and the high voltage DC (+360 V) negative terminal A X3 harness connector at the T6 Power Inverter Module Assembly.
• If greater than the specified value, replace the high voltage DC cables. After the repair is complete with a scan tool, the Clear Secured High Voltage DTCs Reading and Clearing Diagnostic Trouble Codes reset function must be performed.
6. If all circuits test normal, replace the T6 Power Inverter Module Assembly. If the DTC resets, replace the A4 hybrid/EV battery pack assembly.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Drive Motor Battery Wire Junction Block Relay Replacement Drive Motor Battery Wire Junction Block Relay Replacement
* Drive Motor Battery Replacement and Shipping Preparation Procedures
* Control Module References Programming and Relearning for battery energy control module replacement, programming and setup