Toyota Yaris: Air Conditioning System / Room Temperature Sensor Circuit Short to Battery or Open (B141A15)

Toyota Yaris XP210 (2020-2024) Reapir and Service Manual / Vehicle Interior / Heating / Air Conditioning / Air Conditioning System / Room Temperature Sensor Circuit Short to Battery or Open (B141A15)

DESCRIPTION

The cooler thermistor (room temperature sensor) is installed in the instrument panel to detect the cabin temperature, which is used to control the air conditioning system. The resistance of the cooler thermistor (room temperature sensor) changes in accordance with the cabin temperature. As the temperature decreases, the resistance increases. As the temperature increases, the resistance decreases.

The air conditioning amplifier assembly applies voltage (5 V) to the cooler thermistor (room temperature sensor) and reads voltage changes due to changes in the resistance of the cooler thermistor (room temperature sensor).

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	Memory
B141A15	Room Temperature Sensor Circuit Short to Battery or Open	Diagnosis Condition: Ignition switch ON Malfunction Status: Open or short in room temperature sensor circuit Detection Time: Continuously for 4 seconds or more	Cooler thermistor (room temperature sensor) Harness or connector Air conditioning amplifier assembly	Memorized

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

Memory

B141A15

Room Temperature Sensor Circuit Short to Battery or Open

Diagnosis Condition:

Ignition switch ON

Malfunction Status:

Open or short in room temperature sensor circuit

Detection Time:

Continuously for 4 seconds or more

Cooler thermistor (room temperature sensor)
Harness or connector
Air conditioning amplifier assembly

Memorized

DTC Detection Condition Combination Table

		Vehicle Condition
		Pattern 1	Pattern 2
Diagnosis Condition	Ignition switch ON	○	○
Malfunction	Open in room temperature sensor circuit	○	-
Malfunction	Short in room temperature sensor circuit	-	○
Detection Time		Continuously for 4 seconds or more	Continuously for 4 seconds or more
Trip Count		1 trip	1 trip

HINT:

If the conditions of either of these patterns are detected, a DTC will be stored

WIRING DIAGRAM

PROCEDURE

1.	READ VALUE USING GTS (ROOM TEMPERATURE SENSOR)

(a) Read the Data List according to the display on the GTS.

Body Electrical > Air Conditioner > Data List

Tester Display	Measurement Item	Range	Normal Condition	Diagnostic Note
Room Temperature Sensor	Cooler thermistor (room temperature sensor)	Min.: -327.68°C (-557.82°F) Max.: 327.67°C (621.81°F)	Actual cabin temperature displayed	Cooler (room temp. sensor) thermistor circuit malfunction

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Room Temperature Sensor

Cooler thermistor (room temperature sensor)

Min.: -327.68°C (-557.82°F)

Max.: 327.67°C (621.81°F)

Actual cabin temperature displayed

Cooler (room temp. sensor) thermistor circuit malfunction

Body Electrical > Air Conditioner > Data List

Tester Display
Room Temperature Sensor

OK:

The display is as specified in the normal condition column.

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

2.	INSPECT COOLER (ROOM TEMP. SENSOR) THERMISTOR

Click here

REPLACE COOLER (ROOM TEMP. SENSOR) THERMISTOR

3.	CHECK HARNESS AND CONNECTOR (COOLER (ROOM TEMP. SENSOR) THERMISTOR - AIR CONDITIONING AMPLIFIER ASSEMBLY)

(a) Disconnect the H25 air conditioning amplifier assembly connector.

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection	Condition	Specified Condition
H58-1 (+) - H25-5 (TR)	Always	Below 1 Ω
H58-2 (-) - H25-3 (SG-1)	Always	Below 1 Ω
H58-1 (+) or H25-5 (TR) - Other terminals and body ground	Always	10 kΩ or higher
H58-2 (-) or H25-3 (SG-1) - Other terminals and body ground	Always	10 kΩ or higher

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

REPAIR OR REPLACE HARNESS OR CONNECTOR

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