B1201

DTC B1201 HUMIDITY SENSOR SHORT (LOW)

Component Location:

COMPONENT LOCATION

GENERAL DESCRIPTION
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.

DTC DESCRIPTION
The A/C controller sets DTC B1201 if there is a short circuit in humidity sensor signal harness or the measured frequency value of sensor is less than threshold value (about 6,186 Hz)

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 "Humidity Sensor" Parameter on the Scantool while drying the humidity sensor with a hair drier or heat gun adjusted to a low heat setting.
4. Are the DTC B1201 present and is parameter of "Humidity Sensor" fixed?
* Parameter of "Humidity Sensor" will be fixed at 1074, if there is any fault in Humidity Sensor.

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 to ground in harness.
1. Ignition "OFF"
2. Disconnect Humidity Sensor.




3. Measure resistance between terminal "3" of Humidity Sensor and chassis ground.
4. Is the measured resistance within specifications?

YES - Go to "Power circuit Inspection " procedure.

NO - Check for short to ground in harness. Repair as necessary and go to "Verification of Vehicle Repair" procedure.

POWER SUPPLY CIRCUIT INSPECTION
1. Check for open in power harness.
1. Ignition "ON"
2. Disconnect Humidity Sensor.




3. Measure voltage value between terminal "5" of Humidity Sensor and chassis ground.

Specification : 5 V

4. Is the measured voltage within specifications?

YES - Go to "Component Inspection " procedure.

NO - Check for open in power harness. Repair as necessary and go to "Verification of Vehicle Repair" procedure.

COMPONENT INSPECTION
1. Check Humidity Sensor.
1. Engine "ON"
2. Connect Humidity Sensor.







3. Measure Frequency between terminal "3" and "2" of Humidity sensor while increasing humidity.

Specification : Refer the specifications in fig 5.

4. Is the measured frequency within specifications in fig 5? (tolerance limits ± 5%)

YES - Go to "Check A/C Control Unit" procedure.

NO
- 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.

2. Check A/C Control Unit
1. Engine "ON"
2. Disconnect Humidity Sensor.




3. Measure voltage value between terminal "4" of A/C control unit and chassis ground.

Specification : 5 V

4. Is the measured voltage within specification?

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 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.

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.