Dtc 12 Ambient Temperature Sensor Circuit


DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

CHECK ACCESSORY METER ASSEMBLY

CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER - ACCESSORY METER)

INSPECT THERMISTOR ASSEMBLY

CHECK HARNESS AND CONNECTOR (THERMISTOR - ACCESSORY METER)

DTC 12 Ambient Temperature Sensor Circuit


DESCRIPTION

The thermistor assembly connected to the accessory meter detects fluctuations in the ambient temperature. This information is used for controlling the interior temperature. The accessory meter assembly detects the resistance of the thermistor assembly and sends this information to the air conditioning amplifier assembly.

DTC Code
DTC Detection Condition
Trouble Area
12
An open or short in ambient temperature sensor circuit
  1. Thermistor assembly
  2. Accessory meter assembly
  3. Air conditioning amplifier assembly
  4. Harness or connector

WIRING DIAGRAM


Toyota Fortuner. Ggn50, 60 Kun51, 61 Tgn51 Lan50.Air Conditioning.Air Conditioning System (For Automatic Air Conditioning System). Dtc 12 Ambient Temperature Sensor Circuit


INSPECTION PROCEDURE

NOTICE:
Check that the accessory meter assembly illuminates normally before performing the following inspection procedure.
1.CHECK ACCESSORY METER ASSEMBLY

  1. Check the difference between the ambient temperature value displayed on the accessory meter assembly and the actual ambient temperature.

    OK:
    The ambient temperature displayed on the accessory meter assembly and the actual ambient temperature are almost the same.
    HINT:
    The temperature displayed on the accessory meter assembly and the actual temperature detected by the thermistor assembly may differ when the ambient temperature changes significantly (for example, when the vehicle is entering/exiting tunnels, or the vehicle speed or wind direction changes).


NG
Go to step 3
OK


2.CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER - ACCESSORY METER)

  1. Disconnect the A43 accessory meter assembly connector.

  1. Disconnect the A38 air conditioning amplifier assembly connector.

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    A43-9 (DATA) - A38-18 (TAMO)
    		Always
    		Below 1 Ω
    A43-9 (DATA) - Body ground
    		Always
    		10 kΩ or higher
    Result
    Result
    		Proceed to
    OK (When troubleshooting according to problem symptoms table.)
    		A
    OK (When troubleshooting according to DTC.)
    		B
    NG
    		C


B
REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY (Toyota Fortuner RM000001K3A018X.html)

C
REPAIR OR REPLACE HARNESS OR CONNECTOR
A

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE (Toyota Fortuner RM0000045E300YX.html)

3.INSPECT THERMISTOR ASSEMBLY


    Toyota Fortuner. Ggn50, 60 Kun51, 61 Tgn51 Lan50.Air Conditioning.Air Conditioning System (For Automatic Air Conditioning System). Dtc 12 Ambient Temperature Sensor Circuit

  1. Remove the thermistor assembly (Toyota Fortuner RM000002VYK01QX.html).

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    1 - 2
    		10°C (50°F)
    		3.00 to 3.73 kΩ
    15°C (59°F)
    		2.45 to 2.88 kΩ
    20°C (68°F)
    		1.95 to 2.30 kΩ
    25°C (77°F)
    		1.60 to 1.80 kΩ
    30°C (86°F)
    		1.28 to 1.47 kΩ
    35°C (95°F)
    		1.00 to 1.22 kΩ
    40°C (104°F)
    		0.80 to 1.00 kΩ
    45°C (113°F)
    		0.65 to 0.85 kΩ
    50°C (122°F)
    		0.50 to 0.70 kΩ
    55°C (131°F)
    		0.44 to 0.60 kΩ
    60°C (140°F)
    		0.36 to 0.50 kΩ
    Text in Illustration
    *a
    		Resistance (kΩ)
    *b
    		Temperature
    NOTICE:
    1. Even slightly touching the thermistor assembly may change the resistance value. Be sure to hold the connector of the thermistor assembly.
    2. When measuring the resistance, the thermistor assembly temperature must be the same as the ambient temperature.
    HINT:
    As the temperature increases, the resistance decreases (Refer to the graph).


NG
REPLACE THERMISTOR ASSEMBLY (Toyota Fortuner RM000002VYK01QX.html)
OK


4.CHECK HARNESS AND CONNECTOR (THERMISTOR - ACCESSORY METER)

  1. Disconnect the A43 accessory meter assembly connector.

  1. Disconnect the A1 thermistor assembly connector.

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    A43-3 (TH+) - A1-2
    		Always
    		Below 1 Ω
    A43-2 (SG) - A1-1
    A43-3 (TH+) - Body ground
    		Always
    		10 kΩ or higher
    A43-2 (SG) - Body ground


NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE ACCESSORY METER ASSEMBLY (Toyota Fortuner RM000004R7J004X.html)