3.
Monitor the "DR. DIRECTION POTENTIO." parameter on the scantool while operating mode switch.
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.
The A/C controller sets DTC B1250 if there is a short to power in the Direction potentiometer.
Item | Detecting Condition | Possible cause |
DTC Strategy | ● Voltage check | ● Short circuit in harness ● Faulty driver direction potentiometer ● Open circuit in harness |
Threshold value | ● ＞ 4.9V | |
Detecting time | ● 0.3 sec | |
FAIL SAFE | ● Fix vent position |
Connect scantool to Data Link Connector(DLC).
Engine "ON"
Monitor the "DR. DIRECTION POTENTIO." parameter on the scantool while operating mode switch.
Are the DTC B1250 present and is parameter of "DR. DIRECTION POTENTIO." fixed?
※ Parameter of "DR. DIRECTION POTENTIO." will be fixed at 100%(or any value above 90%), or 0% (or any value below 10%), if there is any fault in Driver Direction potentiometer.
Go to "Inspection" procedure.
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.
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.
Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
Has a problem been found?
Repair as necessary and go to "Verification of Vehicle Repair" procedure.
Go to "Signal circuit inspection" procedure.
Check for short in harness.
Ignition "OFF"
Disconnect Driver mode Actuator.
Measure resistance between terminal "6" and "7"of Driver Direction potentiometer.
Specification : Approx. ∞ Ω
Is the measured resistance within specifications?
Go to "Ground circuit inspection" procedure.
Check for open in signal harness. Repair as necessary and go to "Verification of Vehicle Repair" procedure.
Check for open in ground harnesS.
Ignition "OFF"
Disconnect Driver mode Actuator.
Measure resistance between terminal "5" of evaporator sensor and chassis ground.
Specification :Approx. 0 Ω
Is the measured resistance within specifications?
Go to "Component Inspection " procedure.
Check for open in ground harness. Repair as necessary and go to "Verification of Vehicle Repair" procedure.
Check actuator.
Ignition "OFF"
Disconnect Driver Direction potentiometer.
Verify that the mode actuator operates to the vent mode when connecting 12V to the terminal "3" and grounding terminal "4".
Verify that the mode actuator operates to the def mode when the connections are reversed.
Does the actuator work properly?
Go to "Check potentiometer" procedure.
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.
Check potentiometer
Ignition "ON"
Connect Driver Direction potentiometer.
Measure voltage between terminal "5" and "6" of Driver Direction potentiometer as the mode switch is operated.
Specification : Refer the specifications in fig 3
Door position | Voltage (3-4) | Error detecting |
VENT | 0.3 ± 0.15V | Under voltage : 0.08V or less Over voltage : 4.92V or more |
BI-LEVEL(1) | 1.35 ± 0.4V | |
BI-LEVEL(2) | 2.25 ± 0.4V | |
FLOOR | 3.0 ± 0.4V | |
MIX | 3.6 ± 0.4V | |
DEF | 4.7 ± 0.15V |
Is the measured voltage within specifications in fig3?
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.
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.
After a repair, it is essential to verify that the fault has been corrected.
Connect scantool and select "Diagnostic Trouble Codes(DTCs)" mode and then clear DTC.
Operate the vehicle and monitor the DTC on the scantool.
Are any DTCs present?
Go to the applicable troubleshooting procedure.
System is performing to specification at this time.
