3.
Monitor the "Humidity Sensor" Parameter on the Scantool while drying the humidity sensor with a hair drier or heat gun adjusted to a low heat setting.
Humidity sensor located at crush pad, detects in-car humidity for in-car humidity control. If ambient air temperature or in-car humidity is outside certain range, it will turn on A/C to control in-car humidity for preventing in-car fogging. Air conditioner operation depends on ambient temperature and humidity.
The A/C controller sets DTC B1200 if there is an open circuit in humidity sensor signal harness or the measured frequency value of sensor is more than threshold value(about 7,100㎐)
Item | Detecting Condition | Possible cause |
DTC Strategy | ● Frequency check | ● Open Circuit in signal harness ● Faulty Humidity Sensor ● Faulty A/C control unit |
Threshold value | ● ＞ 7,100 Hz | |
Detecting time | ● 10msec | |
FAIL SAFE | ● Control with the value of 10% |
Relative humidity(%) | Frequency(Hz) | Relative humidity(%) | Frequency(Hz) |
20 | 7,100 | 60 | 6,600 |
30 | 6,976 | 70 | 6,468 |
40 | 6,853 | 80 | 6,330 |
50 | 6,728 | 90 | 6,186 |
Connect scantool to data link connector(DLC).
Engine "ON"
Monitor the "Humidity Sensor" Parameter on the Scantool while drying the humidity sensor with a hair drier or heat gun adjusted to a low heat setting.
Are the DTC B1200 present and is parameter of "Humidity Sensor" fixed?
※ Parameter of "Humidity Sensor" will be fixed at 10%, if there is any fault in Humidity Sensor.
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 open in harness.
Ignition "OFF"
Disconnect Humidity Sensor.
Measure resistance between terminal "3" of Humidity Sensor and terminal "4" of A/C Control Unit.
Specification : Approx. 0 Ω
Is the measured resistance within specifications?
Go to "Ground circuit Inspection " procedure.
Check for open in harness. Repair as necessary and go to "Verification of Vehicle Repair" procedure.
Check for open in ground harness.
Ignition "OFF"
Disconnect Humidity Sensor.
Measure resistance between terminal "2" of Humidity Sensor and terminal "12" of A/C Control Unit.
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 Humidity Sensor.
Engine "ON"
Connect Humidity Sensor.
Measure Frequency between terminal "3" and "2" of Humidity sensor while increasing humidity.
Specification : Refer the specifications in fig 5.
Is the measured frequency within specifications in fig 5? (tolerance limits ± 5%)
Go to "Check A/C Control Unit" procedure.
Substitute with a known-good Humidity sensor and check for proper operation.
If the problem is corrected, replace Humidity sensor and then go to "Verification of Vehicle Repair" procedure.
Check A/C Control Unit
Engine "ON"
Disconnect Humidity Sensor.
Measure voltage value between terminal "4" of A/C control unit and chassis ground.
Specification : 5V
Is the measured voltage within specification?
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 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.
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.
