P1EF8
DTC P1EF8
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 Descriptors
DTC P1EF8
- Battery Charger Control Module High Voltage Energy Communication Bus Enable Circuit Low Voltage
For symptom byte information, refer to Symptom Byte List Symptom Byte List.
Diagnostic Fault Information
Circuit/System Description
The Battery Charger compares the high voltage energy management communication enable hardwire signal with a Hybrid Powertrain Control Module 2 serial data message indicating that the high voltage energy management communication enable signal is active. If the high voltage energy management communication enable hardwire signal is low when the serial data message indicates it should be high, then DTC P1EF8 is set.
Conditions for Running the DTC
The device is awake and communicating.
Conditions for Setting the DTC
A short to ground or an open circuit may exist on the high voltage energy communication enable circuit.
Action Taken When the DTC Sets
DTC P1EF8 is a type A DTCs.
Conditions for Clearing the DTC
DTC P1EF8 is a type A DTCs.
Diagnostic Aids
Short to ground will also set multiple no communication codes for devices on high voltage energy serial data bus.
Reference Information
Schematic Reference
* Data Communication Schematics [1][2]Electrical Diagrams
* Control Module References Programming and Relearning
Connector End View Reference
Component Connector End Views Hybrid/EV Battery Pack X1
Description and Operation
Data Link Communications Description and Operation Description and Operation
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
Scan Tool Reference
Control Module References Programming and Relearning for scan tool information
Circuit/System Verification
1. Vehicle in Service Mode.
2. Verify that DTC P1EB9 is not set.
• If DTC P1EB9 is set
Refer to DTC P1EB9 P1EB9.
• If DTC P1EB9 is not set
3. Refer to Circuit/System Testing.
Circuit/System Testing
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 if you have any questions.
Note: Use the schematics and connector end views to identify the devices' high voltage energy management communication enable circuit terminals.
1. Vehicle OFF, disconnect the X1 harness connector at the T18 Battery Charger.
2. Vehicle in Service Mode.
3. Verify that a test lamp illuminates between the high voltage energy management communication enable circuit terminal G X1 and ground.
• If the test lamp does not illuminate, test the circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the K114B hybrid powertrain control module 2.
• If the test lamp does not illuminate
1. Vehicle OFF, disconnect the X1 harness connector at the A4 Hybrid/EV Battery Pack, Vehicle in Service Mode.
2. Verify a test lamp illuminates between the high voltage energy management communication enable circuit terminal G X1 at the T18 Battery Charger and ground.
• If the test lamp illuminates, replace the K16 Battery Energy Control Module.
• If the test lamp does not illuminate
3. Vehicle OFF, disconnect the X2 harness connector at the K114B Hybrid Powertrain Control Module 2.
4. Test for infinite resistance between the high voltage energy management communication enable circuit terminal G X1 at the T18 Battery Charger and ground.
• If less than infinite resistance, repair the short ground on the circuit.
• If infinite resistance
5. Test for less than 2 ohms in the high voltage energy management communication enable circuit end to end between the T18 Battery Charger terminal G X1 and the K114B Hybrid Powertrain Control Module 2 terminal 48 X2.
• If greater than 2 ohms, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K114B Hybrid Powertrain Control Module 2.
• If the test lamp illuminates
4. Replace the T18 Battery Charger.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
Control Module References Programming and Relearning for device replacement, programming and setup