B1234 In-Car Temperature Sensor Open (High) - Automotive Repair Guides & Equipment

COMPONET LOCATION

GENERAL DESCRIPTION

The In Car Tenperature Sensor contains a thermistor which measures the temperature of the inside the vehicle. The signal, based on the resistance value, is delivered to the HVAC control unit. This information is used to control the vent output temperature.

DTC DESCRIPTION

DTC B1234 sets if In-Car temperature sensor signal is at or over 4.9V for 0.3 seconds.

DTC DETECTING CONDITION

Item

Detecting Condition

Possible Cause

DTC Strategy

Voltage check

1.	Open in signal circuit

2.	Short to battery in signal circuit

3.	Faulty In-Car temperature sensor

4.	Faulty A/C Control Unit

Enable Conditions

Ignition ON

Threshold value

Sensor signal is at or over 4.9V for 0.3 seconds

Failsafe

Substituded In-Car Temp. = 25°C (77°F)

SPECIFICATION

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

Temperature(°C/°F)	Resistance(kΩ)	Temperature(°C/°F)	Resistance(kΩ)
-20/-4	285.6	20/68	37.4
-10/14	169	30/86	24.1
0/32	97.7	40/104	15.9
10/50	59.67	50/122	10.8

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.SENSOR1” will be fixed at 25°C(77°F), if there is any fault in INCAR SENSOR.

Is the Incar temperature sensor normal ?

	▶ This is a intermittent problem caused by poor contact of component or Control Unit. ▶ Thoroughly check the looseness, poor connection, bent, corrison, contamination, deformation or damage of connector. ▶ Repair or replace as necessary and then, go to “Verification of Vehicle Repair” procedure.
	▶ Substitute with a known-good Incar temp.sensor and check for proper operation. If the problem is corrected, replace Incar temp.sensor

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