B1245
B1245Component Location:
General Description
Temperature control actuator located at heater unit. It contains temp motor that changes temp door position and potentiometer that monitors position of temp door. Temperature control actuator 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. In operation, potentiometer delivers temp door position transformed into voltage value to A/C ECU.
DTC Description
The ECM sets DTC B1245 if there is an open circuit or poor connection in the driver air mix actuator signal harness.
DTC Detecting Condition:
Schematic Diagram:
Signal Waveform:
Monitor Scantool Data
1. Connect scantool to Data Link Connector (DLC).
2. Engine "ON".
3. Monitor the "DR AIR MIX potentiometer" Parameter on the Scantool. While operating temp switch.
4. Are the DTC B1245 present and is parameter of "DR AIR MIX potentiometer" fixed?
- Parameter of "DR AIR MIX potentiometer" will be fixed at d at 100% (or any value above 90%), or 0% (or any value below 10%), if there is any fault in DR AIR MIX actuator.
YES
a. Go to "Inspection & Repair" procedure.
NO
a. Fault is intermittent caused by poor contact in the sensor's and/or A/C control unit's connector or was repaired and A/C control unit 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
a. Repair as necessary and go to "Verification Vehicle Repair" procedure.
NO
a. Go to "W/Harness Inspection" procedure.
Signal Circuit Inspection
1. Check for open in harness
1. Ignition "OFF".
2. Disconnect DR Air Mix actuator.
3. Measure resistance between terminal "4" of DR Air Mix actuator and terminal "10" of A/C control unit.
Specification : Approx. 0 ohm
4. Is the measured resistance within specifications?
YES
a. Go to "Check for short to ground in harness" procedure.
NO
a. Check for open in signal harness. Repair as necessary and go to "Verification of Vehicle Repair" procedure.
Check for short to ground in harness
5. Ignition "OFF".
6. Disconnect DR Air Mix actuator.
7. Measure resistance between terminal "4" of DR Air Mix actuator and chassis ground.
Specification : Approx. Infinite ohms
8. Is the measured resistance within specifications?
YES
a. Go to "Power circuit Inspection" procedure.
NO
a. 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 open in harness
1. Ignition "ON".
2. Connect DR Air Mix actuator.
3. Measure resistance between terminal "3" of DR Air Mix actuator and terminal "1" of A/C Control Unit.
Specification : Approx. 0 ohm
4. Is the measured resistance within specifications?
YES
a. Go to "Check for short to ground in harness" procedure.
NO
a. 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
5. Ignition "OFF".
6. Disconnect DR Air Mix actuator.
7. Measure resistance between terminal "4" of DR Air Mix actuator and chassis ground.
Specification : Approx. Infinite ohms
8. Is the measured resistance within specifications?
YES
a. Go to "Power circuit Inspection" procedure.
NO
a. Check for short to ground in signal harness. Repair as necessary and go to "Verification of Vehicle Repair" procedure.
Component Inspection
1. Check A/C Control Unit
1. Engine "ON".
2. Disconnect DR Air Mix actuator.
3. Measure voltage value between terminal "1" of A/C control unit and chassis ground.
Specification : 5 V
4. Is the measured voltage within specifications?
YES
a. Go to "Check DR Air Mix actuator" procedure.
NO
a. Substitute with a known-good A/C Control Unit and check for proper operation. If the problem is corrected, replace A/C Control Unit and then go to "Verification of Vehicle Repair" procedure.
2. Check DR Air Mix actuator.
5. Check actuator motor
1. Ignition "OFF".
2. Disconnect DR Air Mix actuator.
3. Connect (+) terminal of battery to terminal 1 of Air Mix actuator and (-) terminal to terminal 2.
4. Verify that the temperature actuator operates to the cool or warm position.
5. Dose the actuator work properly?
YES
a. Go to "Check potentiometer" procedure.
NO
a. 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.
6. Check actuator potentiometer
1. Ignition "ON".
2. Connect DR Air Mix actuator.
3. Measure voltage between terminal "4" and "5" of DR Air Mix actuator while operating the temp switch.
Specification : Refer the specifications in fig 3)
4. Is the measured voltage within specifications in fig 3)?
YES
a. 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
a. 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
a. Go to the applicable troubleshooting procedure.
NO
a. System is performing to specification at this time.