B1249
DTC B1249 DIRECTION POTENTIOMETER OPEN (LOW) - DRIVERComponent Location:
COMPONENT LOCATION
GENERAL DESCRIPTION
The mode control actuator mounted on heater unit, adjusts position of mode door by operating Direction Motor based on signal of A/C control unit. Pressing mode select switch makes the mode control actuator shift in order of vent -> B/L -> floor -> mix.
DTC DESCRIPTION
The A/C controller sets DTC B1249 if there is an open circuit or poor connection in the Direction potentiometer.
DTC Detecting Condition:
DTC DETECTING CONDITION
Specification:
SPECIFICATION
MONITOR SCANTOOL DATA
1. Connect scantool to Data Link Connector (DLC).
2. Engine "ON"
3. Monitor the "DR. DIRECTION POTENTIO." parameter on the scantool while operating mode switch.
4. Are the DTC B1249 present and is parameter of "DR. DIRECTION POTENTIO." fixed?
* Parameter of "DR. DIRECTION POTENTIO." will be fixed at 1OO% (or any value above 90%), or 0% (or any value below 10%), if there is any fault in Driver Direction 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 open in harness.
1. Ignition "OFF"
2. Disconnect Driver mode Actuator.
3. Measure resistance between terminal "6" of Driver Direction potentiometer and terminal "21" of A/C control unit.
Specification : Approx. 0 ohms
4. Is the measured resistance within specifications?
YES - Go to "Check for short to ground in harness" procedure.
NO - Check for open in signal harness. Repair as necessary and go to "Verification of Vehicle Repair" procedure.
2. Check for short to ground in harness.
1. Ignition "OFF"
2. Disconnect Driver mode Actuator.
3. Measure resistance between terminal "6" of Driver Direction potentiometer and chassis ground.
Specification : Approx. Infinity ohms
4. Is the measured resistance within specifications?
YES - Go to "Power circuit Inspection" procedure.
NO - Check for short to ground in signal harness. Repair as necessary and go to "Verification of Vehicle Repair" procedure.
POWER SUPPLY CIRCUIT INSPECTION
1. Check for short or open in harness.
1. Ignition "ON"
2. Connect Driver Direction potentiometer.
3. Measure voltage between terminal "5" of Driver Direction potentiometer and chassis ground.
Specification : Approx. 5 V
4. Is the measured voltage within specifications?
YES - Go to "Component Inspection" procedure.
NO - Check for short or open in power harness. Repair as necessary and go to "Verification of Vehicle Repair" procedure.
COMPONENT INSPECTION
1. Check actuator.
1. Ignition "OFF"
2. Disconnect Driver Direction potentiometer.
3. Verify that the mode actuator operates to the vent mode when connecting 12 V to the terminal "3" and grounding terminal "4".
4. Verify that the mode actuator operates to the def mode 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 Direction potentiometer.
3. Measure voltage between terminal "7" and "6" of Driver Direction potentiometer as the mode switch is operated.
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.