B1234

Component Location






General Description

It contains a thermistor which measures the temperature of the inside. The signal,decided by the resistance value which changes in accordance with perceived inside temperature, is delivered to heater control unit. According to this signal, the control unit regulates incar temperature to intended value.

DTC Description

Air conditioner Control Module sets DTC B1234 if Incar temperature sensor has been detected over 4.9V for 4sec.

DTC Detecting Condition






Specification

** Resistance value of incar temp sensor as a function of temperature.






Diagnostic Circuit Diagram






Monitor Scantool Data

1. Connect scantool with diagnostic connector.
2. Warm up the engine to normal engine temperature after engine starts.
3. Select and monitor "In-car temperature sensor" parameter.






Fig 1) Parameter of "INCAR TEMP.SENSOR" will be fixed at 25°C(77°F), if there is any fault in INCAR SENSOR.
4. Is the Incar temperature sensor normal ?






Terminal & 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?






Signal Circuit Inspection

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

Specification :0V

5. Is the measured voltage within specification?






Check for open in harness
1. Ignition "OFF".
2. Disconnect Incar temp.sensor and A/C control unit main harness connector.
3. Measure resistance between Signal(+) terminal of Incar temp.sensor harness connector and Signal(+) terminal of A/C-ECU harness connector.

Specification :1Ohms below

4. Is the measured resistance within specification?






Ground Circuit Inspection

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

Specification :1Ohms below

4. Is the measured resistance within specification?






Component Inspection

Check Incar temp.sensor
1. Ignition "OFF".
2. Disconnect Incar temp.sensor and Connect A/C control unit main harness connector.
3. Measure resistance between Signal(+) terminal of Incar temp.sensor harness connector and Sensor ground harness connector.(Component side)

Specification :Refer the specifications in fig.1

FIG.1) ** Specifications : Resistance value of incar sensor as a function of temperature.






4. Is "resistance" display near the specified value?






Check A/C-ECU
1. Ignition "OFF".
2. Disconnect Incar temp.sensor and Connect A/C control unit main harness connector.
3. Ignition "ON"(ENGINE "OFF").
4. Measure voltage between Signal(+) terminal of Incar temp.sensor harness connector and chassis ground.(Component side)

Specification :Approx. 5V

5. Is "voltage" display near the specified value?






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?