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 ECM. 
   2. NG: Go to next step. 
2. Check voltage between terminals TAM and E2 of ECM. 

   PREPARATION: 

   Remove ECM with connectors still connected.

   CHECK: 

   1. Turn ignition switch to ON.
   2. Measure voltage between terminals TAM and E2 of ECM 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: Measuring Voltage Between Terminals TAM And E2 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 is displayed, check and replace ECM and A/C amplifier. 
3. Check ambient temperature sensor. 

   PREPARATION: 

   Disconnect ambient temperature sensor (See AMBIENT TEMPERATURE SENSOR ).

   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 - 1.8kΩ 

   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: Measuring Resistance Between Terminals 1 And 2 Of Ambient Temperature Sensor Connector

   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 (INSPECTION, Connectors, Terminal pins, Wiring Harness (Open or Short Circuits)). 
   1. NG: Repair or replace harness or connector. 
   2. OK: Go to next step. 
5. Check harness and connector between ECM and A/C amplifier (INSPECTION, Connectors, Terminal pins, Wiring Harness (Open or Short Circuits)). 
   1. NG: Repair or replace harness or connector. 
   2. OK: Check and replace ECM or A/C amplifier.