DTC P26A6: Engine Coolant Bypass Valve ""A"" Position Sensor Circuit Low: Notes

1.-

DTC detecting condition:

Immediately at fault recognition

Trouble symptom:

Coolant temperature rises slowly
Poor acceleration

Wiring diagram:

Engine Electrical System Ref. to WIRING SYSTEM>ENGINE ELECTRICAL SYSTEM .

Courtesy of SUBARU OF AMERICA, INC.

CAUTION: Use the check board when measuring the ECM terminal voltage and resistance. Ref. to ENGINE (DIAGNOSTICS) (H4DO)>GENERAL DESCRIPTION>PREPARATION TOOL>HOW TO USE CHECK BOARD .

NOTE: After the faulty parts are repaired or replaced, perform the final check in Basic Diagnostic Procedure. Ref. to ENGINE (DIAGNOSTICS) (H4DO)>BASIC DIAGNOSTIC PROCEDURE>PROCEDURE .

CHECK DATA MONITOR .
1. Start the engine.
2. Using the Subaru Select Monitor, read the value in [Coolant Circulation Valve Actual Angle].
NOTE: For detailed operation procedures, refer to "Common (Diagnostics)". Ref. to COMMON (DIAG)>DATA MONITOR .

Is the value of [Coolant Circulation Valve Actual Angle] approx. -95 deg or less?

Yes: Go to 2 .

No: Even if DTC is detected, the circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again.

NOTE: In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.
CHECK HARNESS BETWEEN ECM AND THERMO-CONTROL VALVE ASSEMBLY CONNECTOR (OPEN) .
1. Turn the ignition switch to OFF.
2. Disconnect the connector from ECM.
3. Disconnect the connector from the thermo-control valve assembly.
4. Measure the resistance between ECM connector and thermo-control valve assembly connector.
Connector a terminal

(E158) No. 17 - (E164) No. 3:

(E158) No. 41 - (E164) No. 1:

Is the resistance less than 1Ω?

Yes: Go to 3.

No: Repair the open circuit of the harness between the ECM connector and thermo- control valve assembly connector.
CHECK HARNESS BETWEEN ECM AND THERMO-CONTROL VALVE ASSEMBLY CONNECTOR (SHORT CIRCUIT TO GROUND) .
Measure the resistance between the ECM connector and engine ground.

Connector a terminal

(E158) No. 17 - Engine ground:

(E158) No. 41 - Engine ground:

Is the resistance 1MΩ or more?

Yes: Go to 4 .

No: Repair the short circuit to ground in the harness between the ECM connector and thermo-control valve assembly connector.
CHECK HARNESS BETWEEN ECM AND THERMO-CONTROL VALVE ASSEMBLY CONNECTOR (SHORT TO POWER SUPPLY) .
1. Connect the connector to ECM.
2. Turn the ignition switch to ON.
3. Measure the voltage between thermo-control valve assembly connector and engine ground.
Connector and terminal

(E164) No. 1(+) - Engine ground (-):

Is the voltage 4.5 - 5.5 V?

Yes: Go to 5 .

No: Repair the short circuit to power supply in the harness between the ECM connector and thermo-control valve assembly connector.
CHECK FOR POOR CONTACT .
Check the connection status of ECM connector and thermo-control valve assembly connector.

Is there poor contact of ECM connector or thermo-control valve assembly connector?

Yes: Repair poor contact of ECM connector or thermo-control valve assembly connector.

No: Replace the thermo-control valve assembly. Ref. to COOLING (H4DO)>THERMO CONTROL VALVE ASSEMBLY .