Toyota 4Runner manuals

Toyota 4Runner: Evaporator Temperature Sensor Circuit (B1413/13)

DESCRIPTION

The No. 1 cooler thermistor is installed on the evaporator in the air conditioning unit to detect the temperature of the cooled air that has passed through the evaporator and control the air conditioning. It sends appropriate signals to the No. 1 air conditioning amplifier assembly. The resistance of the No. 1 cooler thermistor changes in accordance with the temperature of the cooled air that has passed through the evaporator. As the temperature decreases, the resistance increases. As the temperature increases, the resistance decreases.

The No. 1 air conditioning amplifier assembly voltage (5 V) to the No. 1 cooler thermistor and reads voltage changes as the resistance of the No. 1 cooler thermistor changes. This sensor is used for frost prevention.

DTC Code

DTC Detection Condition

Trouble Area

B1413/13

An open or short in the No. 1 cooler thermistor circuit.

  • No. 1 cooler thermistor
  • Air conditioning harness assembly
  • No. 1 air conditioning amplifier assembly

WIRING DIAGRAM


PROCEDURE

1.

READ VALUE USING TECHSTREAM (NO. 1 COOLER THERMISTOR)

(a) Use the Data List to check if the No. 1 cooler thermistor is functioning properly (See page ).


Air Conditioner

Tester Display

Measurement Item/Range

Normal Condition

Diagnostic Note

Evaporator Fin Thermistor

No. 1 cooler thermistor /

Min.: -29.7°C (-21.46°F)

Max.: 59.55°C (139.19°F)

Actual evaporator temperature displayed

Open in the circuit: -29.7°C (-21.46°F).

Short in the circuit: 59.55°C (139.19°F).

OK:

The display is as specified in the normal condition column.

Result

Result

Proceed to

OK (When troubleshooting according to problem symptoms table)

A

OK (When troubleshooting according to the DTC)

B

NG

C


A

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE


B

REPLACE NO. 1 AIR CONDITIONING AMPLIFIER ASSEMBLY

C

2.

INSPECT NO. 1 COOLER THERMISTOR

(a) Remove the No. 1 cooler thermistor (See page ).



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

Standard Resistance:

Tester Connection

Condition

Specified Condition

1 - 2

-10°C (14°F)

7.30 to 9.10 kΩ

-5°C (23°F)

5.65 to 6.95 kΩ

0°C (32°F)

4.40 to 5.35 kΩ

5°C (41°F)

3.40 to 4.15 kΩ

10°C (50°F)

2.70 to 3.25 kΩ

15°C (59°F)

2.14 to 2.58 kΩ

20°C (68°F)

1.71 to 2.05 kΩ

25°C (77°F)

1.38 to 1.64 kΩ

30°C (86°F)

1.11 to 1.32 kΩ

Text in Illustration

*a

Sensing Portion

*b

Resistance

*c

Allowable Range

*d

Temperature

NOTICE:

  • Even slightly touching the sensor may change the resistance value. Be sure to hold the connector of the sensor.
  • When measuring, the sensor temperature must be the same as the ambient temperature.

HINT:

As the temperature increases, the resistance decreases (refer to the graph).


NG

REPLACE NO. 1 COOLER THERMISTOR

OK

3.

INSPECT NO. 1 AIR CONDITIONING AMPLIFIER ASSEMBLY

(a) Remove the No. 1 air conditioning amplifier assembly (See page ).



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

Standard Resistance:

Tester Connection

Condition

Specified Condition

z15-6 (TE) - 2

Always

Below 1 Ω

z15-5 (SG-3) - 1

Always

Below 1 Ω

z15-6 (TE) - Body ground

Always

10 kΩ or higher

z15-5 (SG-3) - Body ground

Always

10 kΩ or higher

Text in Illustration

*a

Front view of wire harness connector

(to No. 1 Cooler Thermistor)

*b

Front view of wire harness connector

(to No. 1 Air Conditioning Amplifier Assembly)


OK

REPLACE NO. 1 AIR CONDITIONING AMPLIFIER ASSEMBLY


NG

REPLACE AIR CONDITIONING HARNESS ASSEMBLY

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