W/Harness Inspection

Air Conditioner
B1281 Humidity Sensor Short (Low) - AUTO Defog - Inspection/Repair:_:W/Harness Inspection

Terminal and Connector Inspection

1. Many malfunctions in the electrical system are caused by poor connection. 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?






Power Circuit Inspection

Check power in harness
1. Ignition "OFF"
2. Disconnect Auto Defog sensor and Connect A/C control unit main harness connector.
3. Ignition "ON"
4. Measure voltage between Power terminal of Auto Defog sensor harness connector and chassis ground.

Specification :Approx. 5V




5. Is the measured voltage within specification?






Ground Circuit Inspection

Check for open in harness
1. Ignition "OFF"
2. Disconnect Auto Defog sensor and A/C control unit main harness connector.
3. Measure resistance between Sensor ground terminal of Auto Defog sensor harness connector and Sensor ground terminal of A/C-ECU harness connector.

Specification :below 1Ohms




4. Is the measured resistance within specification?






Signal Circuit Inspection

Check for Signal Waveform
1. Ignition "ON"
2. Connect Auto Defog sensor and A/C control unit main harness connector.
3. Measure signal waveform between Defog Sck terminal of Auto Defog sensor harness connector and chassis ground.(M)1
4. Measure signal waveform between Defog Sck terminal of Auto Defog sensor harness connector and chassis ground.(M)2
5. Measure signal waveform between Defog Sck terminal of Auto Defog sensor harness connector and chassis ground.(M)3





Specification :












Fig.1) M)1
Fig.2) M)2
Fig.3) M)3
6. Is the measured value within specifications?





Check short to ground in harness
1. Ignition "OFF"
2. Disconnect Auto Defog sensor and A/C control unit main harness connector.
3. Measure resistance between Defog Temp terminal of Auto Defog sensor harness connector and chassis ground.
4. Measure resistance between Defog Sck terminal of Auto Defog sensor harness connector and chassis ground.
5. Measure resistance between Defog Data terminal of Auto Defog sensor harness connector and chassis ground.

Specification :Infinity




6. Is the measured resistance within specification?





Check short to battrey in harness
1. Ignition "OFF"
2. Disconnect Auto Defog sensor and Connect A/C control unit main harness connector.
3. Ignition "ON"
4. Measure voltage between Defog Temp terminal of Auto Defog sensor harness connector and chassis ground.
5. Measure voltage between Defog Sck terminal of Auto Defog sensor harness connector and chassis ground.
6. Measure voltage between Defog Data terminal of Auto Defog sensor harness connector and chassis ground.

Specification :Approx. 0V




7. Is the measured voltage within specification?





Check for open in harness
1. Ignition "OFF"
2. Disconnect Auto Defog sensor and A/C control unit main harness connector.
3. Measure resistance between Defog Temp terminal of Auto Defog sensor harness connector and Defog Temp terminal of A/C-ECU harness connector.
4. Measure resistance between Defog Sck terminal of Auto Defog sensor harness connector and Defog Sck terminal of A/C-ECU harness connector.
5. Measure resistance between Defog Data terminal of Auto Defog sensor harness connector and Defog Data terminal of A/C-ECU harness connector.

Specification :Below 1Ohms




6. Is the measured resistance within specification?