P26A7
DTC P2681, P26A3, P26A6, P26A7, or P26A9
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 P2681
- Engine Coolant Bypass Valve Control Circuit
DTC P26A3
- Engine Coolant Bypass Valve Performance
DTC P26A6
- Engine Coolant Bypass Valve Position Sensor Circuit Low Voltage
DTC P26A7
- Engine Coolant Bypass Valve Position Sensor Circuit High Voltage
DTC P26A9
- Engine Coolant Bypass Valve Position Sensor Stop Performance
Circuit/System Description
The Engine Coolant Bypass Valve is also known as the Passenger Compartment Heater Coolant Control Valve. The Passenger Compartment Heater Coolant Control Valve regulates the engine coolant flow into the Cabin Heater Loop depending on engine coolant temperature and ambient temperature conditions. The Passenger Compartment Heater Coolant Control Valve has two positions: ByPass or Link. In the ByPass position, the coolant in the Engine Loop and Heater Loop are separated and in the Link Position the coolant circulates through both loops. The valve movement is controlled by a PWM signal. A 50% duty cycle is a normal duty cycle. A 75% duty cycle represents a valve commanded to the Link position. A 25% duty cycle represents a valve commanded to the ByPass position. The Passenger Compartment Heater Coolant Control Valve uses an internal position sensor that sends a signal to the hybrid powertrain control module to determine the valve position.
When the engine coolant temperature heats up, a valve learn procedure takes place. The hybrid powertrain control module 2 commands the valve to the link position and records the voltage coming back from the position sensor. Then the hybrid powertrain control module 2 commands the valve back to the bypass position and records the voltage coming back from the position sensor. The voltage values in both the link and bypass positions must fall within calibrated ranges.
Conditions for Running the DTC
P2681, P26A6 and P26A7
The system voltage is greater than or equal to 9 V.
P26A3 and P26A9
* The system voltage is greater than or equal to 9 V.
* The propulsion system is active.
* None of the following DTCs are set; P2681, P26A6, P26A7.
Conditions for Setting the DTC
P2681
The hybrid powertrain control module 2 has detected a short to voltage or an open on valve drive circuit.
P26A6
The hybrid powertrain control module 2 has detected a short to ground on feedback circuit. The feedback signal is less than 5% (0.25 V).
P26A7
The hybrid powertrain control module 2 has detected a short to voltage on feedback circuit. The feedback signal is greater than 95% (4.25 V).
P26A3
* The hybrid powertrain control module 2 has detected a stuck valve.
* The valve did not reach the commanded position within 15 seconds after 3 attempts to move the valve.
* The coolant temperature is above 50° C.
OR
* The hybrid powertrain control module 2 has detected a stuck valve.
* The valve did not reach the commanded position within 15 seconds
* The coolant temperature is above 65° C.
P26A9
* The feedback signal is between 70% - 95% (3.5 V - 4.75 V) or between 5% - 30% (0.25 V - 1.5 V)
OR
* The hybrid powertrain control module 2 has detected the valve feedback has drifted beyond acceptable range.
OR
* The hybrid powertrain control module 2 has detected the valve feedback to be erratic beyond acceptable range.
Action Taken When the DTC Sets
DTCs P2681, P26A3, P26A6, P26A7 and P26A9 are type B DTCs.
Conditions for Clearing the DTC
* DTCs P2681, P26A3, P26A6, P26A7 and P26A9 are type B DTCs.
* DTC P26A3 requires the ignition to cycle from ON to OFF.
Diagnostic Aids
* If DTC P0606, P0CE7, P2518 and P26A7 are set, DTC P2518 should be diagnosed first.
* If DTC P0606, P0CE7, and P26A7 are set, DTC P0606 should be diagnosed first.
Reference Information
Schematic Reference
HVAC Schematics HVAC - Automatic
Connector End View Reference
Component Connector End Views Hybrid/EV Battery Pack X1 A4
Description and Operation
Hybrid Cooling System Description and Operation Hybrid Cooling System 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
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 References 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 DTC P2518 is not set.
• If DTC P0606, P0CE7, P2518 and P26A7 are set, refer to DTC P151C or P2516-P2518 P151C
• If DTC P0606, P0CE7 and P26A7 are set, refer to DTC P0601-P0604, P0606, or P062F Data Communications
2. With a scan tool, verify that the Passenger Compartment Heater Coolant Control Solenoid Valve Feedback is between 37%-62%.
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 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.
Danger: This diagnostic has NOT been validated on-vehicle. Follow all safety protocol and utilize all appropriate personal protective equipment to ensure your safety. Failure to follow the procedures exactly as written may result in serious injury or death.
1. Ignition OFF, disable the high voltage. Refer to High Voltage Disabling High Voltage Disabling.
2. Ignition OFF, disconnect the X1 harness connector at the Passenger Compartment Heater Coolant Control Solenoid Valve.
3. Ignition OFF and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down. Test for less than 10 ohm between the low reference circuit terminal 5 and ground.
• If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the hybrid powertrain control module 2.
4. Test for less than 10 ohm between the control circuit terminal 2 and ground.
• If greater than the specified range, test the control circuit for an open/high resistance. If the circuit tests normal, replace the hybrid powertrain control module 2.
5. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal 3 and ground.
• If less than the specified range, test the 5 V reference circuit for a short to ground or an open/high resistance. If the circuit is grounded, disconnect the X1 harness connector at the hybrid powertrain control module 2. If the ground is eliminated, disconnect the X1 harness connector at the hybrid battery pack coolant control valve, test the 5 V reference circuit for a short to ground at terminal 6 X1 at the hybrid battery pack coolant control valve. If the circuits tests normal, replace the hybrid powertrain control module 2.
• If greater than the specified range, test the 5 V reference circuit for a short to voltage. Disconnect the X1 harness connector at the hybrid powertrain control module 2. If the short to voltage is eliminated, disconnect the X1 harness connector at the hybrid battery pack coolant control valve, test the 5 V reference circuit for a short to voltage at terminal 6 X1 at the at the hybrid battery pack coolant control valve. If the circuits tests normal, replace the hybrid powertrain control module 2.
6. Verify the scan tool Passenger Compartment Heater Coolant Control Solenoid Valve Feedback parameter is greater than 95%.
• If less than the specified range, test the signal circuit terminal 4 for a short to ground. If the circuit tests normal, replace the hybrid powertrain control module 2.
7. Install a 3 A fused jumper wire between the signal circuit terminal 4 and the low reference circuit terminal 5. Verify the scan tool Passenger Compartment Heater Coolant Control Solenoid Valve Feedback parameter is less than 10%.
• If greater than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the hybrid powertrain control module 2.
8. If all circuits test normal, test or replace the passenger compartment heater coolant control solenoid valve.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Heater Water Shutoff Valve Replacement Service and Repair
* Control Module References Control Module References for the hybrid powertrain control module 2 replacement, programming and setup