DTC B1412: Ambient Temperature Sensor Circuit: Procedure

1. Use the Techstream to check if the CAN communication system is functioning normally.

   Result

   Result	Proceed to
   CAN DTC is not output	A
   CAN DTC is output	B

B → See step   6 

A: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Enter the following menus: Body / Air Conditioner / Data List.
5. Check the value(s) by referring to the table below.
   AIR CONDITIONER
   
   

   Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
   Ambient Temp Sensor (Ambi Temp Sens)	Ambient temperature sensor / Min: -23.3°C (-9.94°F), Max: 65.95°C (150.71°F)	Actual ambient temperature displayed	Open in circuit: -23.3°C (-9.94°F) Short in circuit: 65.95°C (150.71°F)

   OK

   The display is as specified in the "Normal Condition" column.

   Result

   Result	Proceed to
   NG	A
   OK (When troubleshooting according to Problem Symptoms Table)	B
   OK (When troubleshooting according to the DTC output)	C

C → See step   9 

B → See step   7 

A: Go to next step 

1. Disconnect the connector from the combination meter.
   Fig 1: Identifying E46 Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   E46-9 (TX1+) - E46-23 (TEMP)	25°C (77°F)	1.60 to 1.80 kΩ
   E46-9 (TX1+) - E46-23 (TEMP)	40°C (104°F)	0.80 to 1.00 kΩ

   TEXT IN ILLUSTRATION
   
   

   *a	Front view of wire harness connector (to Combination Meter)

NG → See step   5 

OK: Go to next step 

1. Temporarily replace the combination meter with a known good one. Refer to REMOVAL .

   HINT: 

   Since the combination meter cannot be inspected while it is removed from the vehicle, replace the combination meter with a known good one and check that the condition returns to normal.

2. Check for DTCs.

   Result

   Result	Proceed to
   DTC B1412 is not output	A
   DTC B1412 is output	B

B → See step   9 

A → See step   10 

1. Remove the ambient temperature sensor.
2. Disconnect the connector from the ambient temperature sensor.
   Fig 2: Identifying A23 Connector Terminals & Graph

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A23-1 - A23-2	10°C (50°F)	3.00 to 3.73 kΩ
   A23-1 - A23-2	15°C (59°F)	2.45 to 2.88 kΩ
   A23-1 - A23-2	20°C (68°F)	1.95 to 2.30 kΩ
   A23-1 - A23-2	25°C (77°F)	1.60 to 1.80 kΩ
   A23-1 - A23-2	30°C (86°F)	1.28 to 1.47 kΩ
   A23-1 - A23-2	35°C (95°F)	1.00 to 1.22 kΩ
   A23-1 - A23-2	40°C (104°F)	0.80 to 1.00 kΩ
   A23-1 - A23-2	45°C (113°F)	0.65 to 0.85 kΩ
   A23-1 - A23-2	50°C (122°F)	0.50 to 0.70 kΩ
   A23-1 - A23-2	55°C (131°F)	0.44 to 0.60 kΩ
   A23-1 - A23-2	60°C (140°F)	0.36 to 0.50 kΩ

   NOTE:

   • 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. See Fig 2.).

   TEXT IN ILLUSTRATION
   
   

   *a	Component without harness connected (Ambient Temperature Sensor)
   *b	Sensing Portion
   *c	Resistance (kΩ)
   *d	Allowable Range
   *e	Temperature (°C (°F))

NG → See step   8 

OK → REPAIR OR REPLACE HARNESS OR CONNECTOR (AMBIENT TEMPERATURE SENSOR - COMBINATION METER)