Toyota Tundra. Manual — part 2398

DATA LIST

OK:

The display is as specified in the normal condition.

Result

RESULT REFERENCE

B: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS
TABLE (See PROBLEM SYMPTOMS TABLE )

C: REPLACE AIR CONDITIONING AMPLIFIER (See REMOVAL )

A: Go to Next Step

2. INSPECT NO. 1 COOLER THERMISTOR (EVAPORATOR FIN THERMISTOR)

Fig. 36: Temperature And Resistance Graph
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

a. Remove the No. 1 cooler thermistor (evaporator temperature sensor) connector (see

DISASSEMBLY ).

Tester Display

Measurement Item/Range

Normal Condition

Diagnostic Note

Evaporator Fin

Thermistor

Evaporator fin
thermistor/Min.:-29.7°C (-
21.46°F)
Max.: 59.55°C (139.19°F)

Actual evaporator
temperature is displayed

Open in circuit: -
29.7°C (-21.46°F)
Short in circuit:
59.55°C (139.19°F)

Result

Proceed to

NG

A

OK (Checking from the PROBLEM SYMPTOMS TABLE)

B

OK (Checking from the DTC)

C

2009 Toyota Tundra

2009 HVAC Air Conditioning - Tundra

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

Standard Resistance

TESTER CONNECTION SPECIFIED CONDITION CHART

HINT:

As the temperature increases, the resistance decreases (see the graph ).

NG: REPLACE NO. 1 COOLER THERMISTOR (EVAPORATOR FIN THERMISTOR)
(See DISASSEMBLY )

OK: Go to Next Step

3. REPAIR OR REPLACE AIR CONDITIONING HARNESS

a. Repair or replace the air conditioning harness.

4. CHECK FOR DTC

a. Clear the DTC (see DTC CHECK/CLEAR ).

b. Check for DTC (see DTC CHECK/CLEAR ).

OK:

DTC is not output.

NG: REPLACE AIR CONDITIONING AMPLIFIER (See REMOVAL )

OK: END

Tester Connection Condition Specified Condition

1 - 2

-10°C (14°F) 7.30 to 9.10 kohms

-5°C (23°F) 5.65 to 6.95 kohms

0°C (32°F)

4.40 to 5.35 kohms

5°C (41°F)

3.40 to 4.15 kohms

10°C (50°F) 2.70 to 3.25 kohms
15°C (59°F) 2.14 to 2.58 kohms
20°C (68°F) 1.71 to 2.05 kohms
25°C (77°F) 1.38 to 1.64 kohms
30°C (86°F) 1.11 to 1.32 kohms

NOTE:



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.

2009 Toyota Tundra

2009 HVAC Air Conditioning - Tundra

DTC B1421/21 SOLAR SENSOR CIRCUIT (PASSENGER SIDE)

DESCRIPTION

The solar sensor, which is installed on the upper side of the instrument panel, detects sunlight and controls the
air conditioning in AUTO mode. The output current from the solar sensor varies according to the amount of
sunlight. When the sunlight increases, the output current increases. As the sunlight decreases, the output current
decreases. The air conditioning amplifier detects output current from the solar sensor.

Fig. 37: Solar Sensor Output Voltage Graph
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

DTC DETECTION CONDITION CHART

WIRING DIAGRAM

DTC

DTC Detection Condition

Trouble Area

B1421/21

Open or short in passenger side
solar sensor circuit



Automatic light control
sensor (solar sensor)



Harness and connector
between solar sensor and air
conditioning amplifier



Harness and connector
between solar sensor and
main body ECU



Main body ECU



Air conditioning amplifier

2009 Toyota Tundra

2009 HVAC Air Conditioning - Tundra

Fig. 38: Solar Sensor - Wiring Diagram
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

INSPECTION PROCEDURE

HINT:

If DTC B1244 is output at the same time, troubleshoot DTC B1244 first (see DTC B1244 LIGHT SENSOR
CIRCUIT MALFUNCTION ).

1. READ VALUE USING TECHSTREAM (SOLAR SENSOR (for Passenger Side))

a. Use the Data List to check if the passenger side solar sensor is functioning properly.

Air Conditioner

DATA LIST

OK:

The display is as specified in the normal condition.

Result

RESULT REFERENCE

Tester

Display

Measurement

Item/Range

Normal Condition

Diagnostic

Note

Solar Sensor

(P Side)

Passenger side solar
sensor/Min.: 0
Max.: 255

Passenger side solar sensor voltage
increases as brightness increases

Open in circuit:
0
Short in circuit:
255

2009 Toyota Tundra

2009 HVAC Air Conditioning - Tundra