B1246

COMPONENT LOCATION





GENERAL DESCRIPTION

Temperature control actuator located at heater unit, regulates the temperature by the procedure as follows. Signal from control unit adjusts position of temp. door by operating temp. motor and then temperature will be regulated by the hot/cold air ratio decided by position of temp. door.

DTC DESCRIPTION

The A/C controller sets DTC B1246 if there is a short to power in the air mix potentiometer.

DTC DETECTING CONDITION





SPECIFICATION





MONITOR SCANTOOL DATA

1. Connect scantool to Data Link Connector(DLC).
2. Engine "ON"
3. Monitor the "Driver Air Mix Potentiometer" Parameter on the Scantool while operating temp. switch.




4. Are the DTC B1246 present and is parameter of "Driver Air Mix potentiometer" fixed?
** Parameter of "Driver Air Mix potentiometer" will be fixed at 100%(or any value above 90%), or 0% (or any value below 10%), if there is any fault in Driver Air Mix potentiometer.
YES
Go to "Inspection" procedure.
NO
Fault is intermittent caused by poor contact in the sensor's and/or A/C controller's connector or was repaired and A/C controller memory was not cleared. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and then go to "Verification of Vehicle Repair" procedure.

TERMINAL AND CONNECTOR INSPECTION

1. Many malfunctions in the electrical system are caused by poor harness and terminals.
Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
2. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
3. Has a problem been found?
YES
Repair as necessary and go to "Verification of Vehicle Repair" procedure.
NO
Go to "Signal circuit inspection" procedure.

SIGNAL CIRCUIT INSPECTION

1. Check for short in harness.
(1) Ignition "OFF"
(2) Disconnect Driver Air Mix potentiometer.
(3) Measure resistance between terminal "6" and "5" of Driver Air Mix potentiometer.

Specification : Approx. Infinity Ohms





(4) Is the measured resistance within specifications?
YES
Go to "Ground circuit Inspection" procedure.
NO
Check for short to power harness in signal harness. Repair as necessary and go to "Verification of Vehicle Repair" procedure.

GROUND CIRCUIT INSPECTION

1. Check for open in harness.
(1) Ignition "OFF"
(2) Disconnect Driver Air Mix Potentiometer.
(3) Measure resistance between terminal "7" of Driver Air Mix Potentiometer and chassis ground.

Specification : Approx. 0 Ohms





(4) Is the measured resistance within specifications?
YES
Go to "Component Inspection" procedure.
NO
Check for open in ground harness. Repair as necessary and go to "Verification of Vehicle Repair" procedure.

COMPONENT INSPECTION

1. Check actuator motor.
(1) Ignition "OFF"
(2) Disconnect Driver Air Mix Potentiometer.
(3) Verify that the temperature actuator operates to the hot position when connecting 12V to the terminal "3" and grounding terminal "4".
(4) Verify that the temperature actuator operates to the cool position when the connections are reversed.




(5) Does the actuator work properly?
YES
Go to "Check potentiometer" procedure.
NO
Substitute with a known-good actuator and check for proper operation. If the problem is corrected, replace actuator and then go to "Verification of Vehicle Repair" procedure.
2. Check potentiometer
(1) Ignition "ON"
(2) Connect Driver Air Mix potentiometer.
(3) Measure voltage between terminal "6" and "7" of Driver Air Mix potentiometer while operating the temp. switch.

Specification : Refer the specifications in fig 3)














(4) Is the measured voltage within specifications in fig3?
YES
Check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and then go to "Verification of Vehicle Repair" procedure.
NO
Substitute with a known-good actuator and check for proper operation. If the problem is corrected, replace actuator and then go to "Verification of Vehicle Repair" procedure.

VERIFICATION OF VEHICLE REPAIR

After a repair, it is essential to verify that the fault has been corrected.
1. Connect scantool and select "Diagnostic Trouble Codes(DTCs)" mode and then clear DTC.
2. Operate the vehicle and monitor the DTC on the scantool.
3. Are any DTCs present?
YES
Go to the applicable troubleshooting procedure.
NO
System is performing to specification at this time.