B1233

DTC B1233 IN-CAR TEMPERATURE SENSOR SHORT (LOW)

Component Location:

GENERAL DESCRIPTION
The in car temperature sensor located at crush pad, control unit 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 and according to this signal, the control unit regulates in-car temperature to intended value.

DTC DESCRIPTION
The A/C controller sets DTC B1233 it there is a short circuit in in-car temp. sensor signal harness or the measured resistance value of sensor is less than threshold value (about 7.46 Kohm)

DTC Detecting Condition:

Specification:

MONITOR SCANTOOL DATA
1. Connect scantool to data link connector (DLC).
2. Engine "ON"
3. Monitor the "IN CAR TEMP SENSOR" Parameter on the Scantool.






4. Are the DTC B1233 present and is parameter of "IN CAR TEMP SENSOR" fixed?
- Parameter of "IN CAR TEMP SENSOR" will be fixed at 25 °C (77 °F), if there is any fault in IN-CAR TEMP 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 in-car sensor.
3. Measure resistance between terminal "4" of in-car sensor and chassis ground.

Specification : Approx. infinite ohms






4. Is the measured resistance within specifications?

YES - Go to "Component Inspection" procedure.

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

COMPONENT INSPECTION
1. Check in-car temp. sensor.
1. Ignition "OFF"
2. Disconnect in-car sensor.
3. Measure resistance between terminal "4" and "2" of in-car sensor.

Specification : Refer the specifications in fig 3.









4. Is the measured resistance within specifications in fig3? (tolerance limits ± 3%)

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

NO - Substitute with a known-good in-car sensor and check for proper operation.
If the problem is corrected, replace in-car sensor and then go to "Verification of Vehicle Repair" procedure.

2. Check A/C Control Unit
1. Engine "ON"
2. Disconnect in-car sensor.
3. Measure Voltage between terminal "5" of A/C Control Unit and chassis ground.

Specification : Approx. 5 V






4. Is the measured voltage within specifications?

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 verity 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.