Toyota Venza: Ambient Temperature Sensor Circuit (B1412/12)
DESCRIPTION
The ambient temperature sensor is installed in front of the condenser. It detects the ambient temperature to control air conditioning AUTO mode. This sensor is connected to the A/C amplifier and detects fluctuations in the ambient temperature. This data is used for controlling the cabin temperature. The sensor sends a signal to the A/C amplifier. The resistance of the ambient temperature sensor changes in accordance with the ambient temperature. As the temperature decreases, the resistance increases. As the temperature increases, the resistance decreases.
The A/C amplifier applies voltage (5 V) to the ambient temperature sensor and reads voltage changes as the resistance of the ambient temperature sensor changes.
|
DTC No. |
DTC Detection Condition |
Trouble Area |
|---|---|---|
|
B1412/12 |
Open or short in ambient temperature sensor circuit |
|
WIRING DIAGRAM
PROCEDURE
|
1. |
READ VALUE USING TECHSTREAM |
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream on.
(d) Enter the following menus: Body / Air Conditioner / Data List.
(e) Check the value(s) by referring to the table below.
Air Conditioner|
Tester Display |
Measurement Item/Range |
Normal Condition |
Diagnostic Note |
|---|---|---|---|
|
Ambient Temp Sensor |
Ambient temperature sensor / Min: -23.3°C (-9.94°F) Max: 65.95°C (150.71°F) |
Actual ambient temperature displayed |
- |
OK:
The display is as specified in the Normal Condition column.
|
Result |
Proceed to |
|---|---|
|
NG |
A |
|
OK (When troubleshooting according to Problem Symptoms Table) |
B |
|
OK (When troubleshooting according to the DTC) |
C |
| B | .gif) |
PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE |
| C | |
REPLACE A/C AMPLIFIER |
|
.gif)
|
2. |
INSPECT AMBIENT TEMPERATURE SENSOR |
(a) Remove the ambient temperature sensor.
(b) Disconnect the ambient temperature sensor connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
A4-1 - A4-2 |
10°C (50°F) |
3.00 to 3.73 kΩ |
|
A4-1 - A4-2 |
15°C (59°F) |
2.45 to 2.88 kΩ |
|
A4-1 - A4-2 |
20°C (68°F) |
1.95 to 2.30 kΩ |
|
A4-1 - A4-2 |
25°C (77°F) |
1.60 to 1.80 kΩ |
|
A4-1 - A4-2 |
30°C (86°F) |
1.28 to 1.47 kΩ |
|
A4-1 - A4-2 |
35°C (95°F) |
1.00 to 1.22 kΩ |
|
A4-1 - A4-2 |
40°C (104°F) |
0.80 to 1.00 kΩ |
|
A4-1 - A4-2 |
45°C (113°F) |
0.65 to 0.85 kΩ |
|
A4-1 - A4-2 |
50°C (122°F) |
0.50 to 0.70 kΩ |
|
A4-1 - A4-2 |
55°C (131°F) |
0.44 to 0.60 kΩ |
|
A4-1 - A4-2 |
60°C (140°F) |
0.36 to 0.50 kΩ |
NOTICE:
- Hold the sensor only by its connector. Touching the sensor may change the resistance value.
- When measuring, the sensor temperature must be the same as the ambient temperature.
HINT:
As the temperature increases, the resistance decreases (see the graph).
Text in Illustration|
*1 |
Component without harness connected (Ambient Temperature Sensor) |
|
*2 |
Sensing Portion |
| NG | |
REPLACE AMBIENT TEMPERATURE SENSOR |
|
|
3. |
CHECK HARNESS AND CONNECTOR (AMBIENT TEMPERATURE SENSOR - A/C AMPLIFIER) |
|
(a) Disconnect the A/C amplifier connector. |
|
|
(b) Measure the resistance according to the value(s) in the table below. Standard Resistance:
|
|
| OK | |
REPLACE A/C AMPLIFIER |
| NG | |
REPAIR OR REPLACE HARNESS OR CONNECTOR |
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