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DTC P2681, P26A3, P26A6, P26A7, or P26A9

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

12 V battery system voltage is greater than or equal to 10.25 V.

P26A3 and P26A9

    • 12 V battery system voltage is greater than or equal to 10.25 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.

Reference Information

Schematic Reference

HVAC Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Automatic HVAC Description and Operation

Electrical Information Reference

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

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification
  1. Verify that DTC P2518 is not set.
    2. ⇒If DTC P0606, P0CE7, P2518 and P26A7 are set, refer to DTC P151C or P2516-P2518
    ⇒If DTC P0606, P0CE7 and P26A7 are set, refer to DTC P0601-P0604, P0606, or P062F
  2. With a scan tool, verify that the Passenger Compartment Heater Coolant Control Solenoid Valve Feedback is between 37%-62%.

Circuit/System Testing
  1. Vehicle OFF and all vehicle systems OFF. Disconnect the harness connector at the Q66 Passenger Compartment Heater Coolant Control Valve. It may take up to 2 minutes for all vehicle systems to power down.
  2. Test for less than 10 Ω between the ground circuit terminal 6 and ground.
    3. ⇒If 10 Ω or greater
    2.1. Vehicle OFF.
    2.2. Test for less than 2 Ω in the ground circuit end to end.
    ⇒If 2 Ω or greater, repair the open/high resistance in the circuit.
    ⇒If less than 2 Ω, repair the open/high resistance in the ground connection.
    ⇓   If less than 10 Ω
  3. Test for less than 10 Ω between the low reference circuit terminal 5 and ground.
    4. ⇒If 10 Ω or greater
    3.1. Disconnect the harness connector at the K114B HPCM2.
    3.2. Test for less than 2 Ω in the low reference circuit end to end.
    ⇒     If 2 Ω or greater, repair the open/high resistance in the circuit.
    ⇒     If less than 2 Ω, replace the K114B HPCM2.
    ⇓   If less than 10 Ω
  4. Verify a test lamp illuminates between the B+ circuit terminal 1 and ground.
    5. ⇒If the test lamp does not illuminate and the circuit fuse is good
    4.1. Vehicle OFF.
    4.2. Test for less than 2 Ω in the B+ circuit end to end.
    ⇒     If 2 Ω or greater, repair the open/high resistance in the circuit.
    ⇒     If less than 2 Ω, verify the fuse is not open and there is voltage at the fuse.
    ⇒If the test lamp does not illuminate and the circuit fuse is open
    4.1. Vehicle OFF.
    4.2. Test for infinite resistance between the B+ circuit and ground.
    ⇒     If less than infinite resistance, repair the short to ground on the circuit.
    ⇒     If infinite resistance, replace the X50A Underhood Fuse Block.
    ⇓   If the test lamp illuminates
  5. Vehicle ON.
  6. Test for 4.8-5.2 V between the 5 V reference circuit terminal 3 and ground.
    7. ⇒If less than 4.8 V
    6.1. Vehicle OFF, disconnect the harness connector at the K114B HPCM2.
    6.2. Test for infinite resistance between the 5 V reference circuit and ground.
    ⇒     If less than infinite resistance, repair the short to ground on the circuit.
    ⇓     If infinite resistance
    6.3. Test for less than 2 Ω in the 5 V reference circuit end to end.
    ⇒     If 2 Ω or greater, repair the open/high resistance in the circuit.
    ⇒     If less than 2 Ω, replace the K114B HPCM2.
    ⇒If greater than 5.2 V
    6.1. Vehicle OFF, disconnect the harness connector at the K114B HPCM2, vehicle ON.
    6.2. Test for less than 1 V between the 5 V reference circuit and ground.
    ⇒     If 1 V or greater, repair the short to voltage on the circuit.
    ⇒     If less than 1 V, replace the K114B HPCM2.
    ⇓   If between 4.8-5.2 V
  7. Verify the scan tool Passenger Compartment Heater Coolant Control Valve Feedback parameter is less than 10%.
    8. ⇒If 10% or greater
    7.1. Vehicle OFF, disconnect the harness connector at the K114B HPCM2, vehicle ON.
    7.2. Test for less than 1 V between the signal circuit terminal 4 and ground.
    ⇒     If 1 V or greater, repair the short to voltage on the circuit.
    ⇒     If less than 1 V, replace the K114B HPCM2.
    ⇓   If less than 10%
  8. Install a 3 A fused jumper wire between the signal circuit terminal 4 and the 5 V reference circuit terminal 3.
  9. Verify the scan tool Passenger Compartment Heater Coolant Control Valve Feedback parameter is greater than 10%.
    10. ⇒If 10% or less
    9.1. Vehicle OFF, disconnect the harness connector at the K114B HPCM2.
    9.2. Test for infinite resistance between the signal circuit terminal 4 and ground.
    ⇒     If less than infinite resistance, repair the short to ground on the circuit.
    ⇓     If infinite resistance
    9.3. Test for less than 2 Ω in the signal circuit end to end.
    ⇒     If 2 Ω or greater, repair the open/high resistance in the circuit.
    ⇒     If less than 2 Ω, replace the K114B HPCM2.
    ⇓   If greater than 95%
  10. Connect a test lamp between the control circuit terminal 2 and the B+ circuit terminal 1.
  11. Verify the test lamp turns ON and OFF when Commanding the Passenger Compartment Heater Coolant Control Valve ON and OFF with a scan tool.
    12. ⇒If the test lamp is always OFF
    11.1. Vehicle OFF, disconnect the harness connector at the K114B HPCM2.
    11.2. Test for less than 1 V between the control circuit and ground.
    ⇒     If 1 V or greater, repair the short to voltage on the circuit.
    ⇓     If less than 1 V
    11.3. Vehicle OFF.
    11.4. Test for less than 2 Ω in the control circuit end to end.
    ⇒     If 2 Ω or greater, repair the open/high resistance in the circuit.
    ⇒     If less than 2 Ω, replace the K114B HPCM2.
    ⇒If the test lamp is always ON
    11.1. Vehicle OFF, disconnect the harness connector at the K114B HPCM2.
    11.2. Test for infinite resistance between the control circuit terminal 2 and ground.
    ⇒     If less than infinite resistance, repair the short to ground on the circuit.
    ⇒     If infinite resistance, replace the K114B HPCM2.
    ⇓   If the test lamp turns ON and OFF
  12. Test or replace the Q66 passenger compartment heater coolant control valve.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Heater Water Shutoff Valve Replacement
    • Control Module References for the hybrid powertrain control module 2 replacement, programming and setup
   


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