Inspection Procedure

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 form step  2.

1. Check ambient temp, sensor using LEXUS hand-held tester. 

   PREPARATION: 

   Connect the LEXUS hand-held tester to the DLC3.

   CHECK: 

   Check the ambient temp, sensor using DATA LIST.

   1. OK : Check and replace A/C ECU. 
   2. NG : Go to next step. 
2. Check voltage between terminals TAM and ETAM of ECM connector. 

   PREPARATION: 

   Remove ECM with connectors still connected.

   CHECK: 

   1. Turn ignition switch to ON.
   2. Measure voltage between terminals TAM and ETAM of engine and ECU ECU connector at each temperature.

   OK: 

   Voltage : 

   at 25°C (77°F) : 1.35 - 1.75 V 

   at 40°C (104°F) : 0.85 - 1.25 V 

   Fig 1: Identifying Voltage Between Terminals Tam And ETAM Of ECM 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  PROBLEM SYMPTOMS TABLE  ). However, if DTC B1412/12 is displayed, check and replace ECM and A/C ECU. 
3. Check ambient temperature sensor. 

   PREPARATION: 

   Disconnect ambient temperature sensor connector.

   CHECK: 

   Measure resistance between terminals 1 and 2 of ambient temperature sensor connector at each temperature.

   OK: 

   Resistance : 

   at 25°C (77°F) : 1.6 - 1.8 kΩ 

   at 50°C (122°F) : 0.5 - 0.7 kΩ 

   HINT:

   As the temperature increases, the resistance decreases.

   NOTE: When installing the ambient temperature sensor, be sure to connect the sensor connector before connecting the battery.
   Fig 2: Identifying Ambient Temperature Sensor

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   1. NG : Replace ambient temperature sensor. 
   2. OK : Go to next step. 
4. Check harness and connector between ECM and ambient temperature sensor (See  HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE  ). 
   1. NG : Repair or replace harness or connector. 
   2. OK : Check multiplex communication system.