Inspection Procedure

WARNING: This page is about a different car, the 2003 Lexus LS 430. However, it is still accessible from the selected car via links, so may be relevant.

HINT:

In case of using the LEXUS hand- held tester, start the inspection step 1 and in case of not using the LEXUS hand-held tester, start from step 2.

Check air duct sensor using LEXUS hand- held tester.
PREPARATION:

Connect the LEXUS hand-held tester to the DLC3.

CHECK:

Check the air duct sensor using DATA LIST.
1. OK : Check and replace A/C ECU.
2. NG : Go to next step.
Check voltage between terminals TFACEPa and SG-4 of A/C ECU connector.
PREPARATION:

Remove A/C ECU with connectors still connected.

CHECK:
1. Turn ignition switch to ON.
2. Check voltage between terminals TFACEPa and SG-4 of A/C ECU connector at each temperature.
OK:

Voltage:

at 25°C (77°F): 1.8 - 2.2 V

at 50°C (122°F): 0.8 - 1.2 V

Fig 1: Identifying Terminals TFACEPa And SG-4 Of A/C ECU Connector
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

HINT:

As the temperature increases, the voltage decreases.
1. NG : Go to step 3.
2. OK : Proceed to next circuit inspection shown on problem symptoms table (See HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE ). However, if DTC B1416/16 is displayed, check and replace A/C ECU.
Check duct sensor.
PREPARATION:

Remove duct sensor (See DUCT SENSOR ).

CHECK:

Check resistance between terminals 1 and 2 of duct sensor connector at each temperature.

OK:

Resistance:

at 0°C (32°F): 14.5 - 19.0 kΩ

at 25°C (77°F): 4.8 - 5.2 kΩ

at 50°C (122°F): 1.6 - 2.0 kΩ.

Fig 2: Identifying Duct Sensor
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

HINT:

As the temperature increases, the resistance decreases.
1. NG : Replace duct sensor.
2. OK : Go to next step.
Check harness and connector between A/C ECU and duct sensor (See HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE ).
1. NG : Repair or replace harness or connector.
2. OK : Check and replace A/C ECU.