Inspection Procedure

HINT:

Read freeze frame data using the intelligent tester. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air-fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.

1. INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE) 
   1. Disconnect the A3 Air-Fuel Ratio (A/F) sensor connector.
   2. Measure the resistance according to the value (s) in the table below.

      Standard resistance 

      AIR FUEL RATIO SENSOR TESTER CONNECTION AND SPECIFIED CONDITION
      
      

      Tester Connection	Specified Condition
      HT (1) - +B (2)	1.8 to 3.4 Ω at 20°C (68°F)
      HT (1) - AF - (4)	10 kΩ or higher

   NG: REPLACE AIR FUEL RATIO SENSOR 

   Fig 1: Identifying Air Fuel Ratio Sensor Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   OK: GO TO NEXT STEP 

2. INSPECT EFI RELAY (Marking: EFI) 
   1. Remove the EFI relay from the engine room relay block.
   2. Measure the EFI relay resistance according to the value (s) in the table below.

      Standard resistance 

      EFI RELAY TESTER CONNECTION AND SPECIFIED CONDITION
      
      

      Tester Connection	Specified Condition
      3-5	10 kΩ or higher
      3-5	Below 1 Ω (when battery voltage is applied to terminals 1 and 2)

   NG: REPLACE EFI RELAY 

   Fig 2: Identifying EFI Relay Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   OK: GO TO NEXT STEP 

3. INSPECT ECM (HT1A VOLTAGE) 
   1. Turn the ignition switch to the ON position.
   2. Measure the voltage according to the value (s) in the table below.

      Standard voltage 

      ECM TESTER CONNECTION AND SPECIFIED CONDITION
      
      

      Tester Connection	Specified Condition
      HA1A (E8-1) - Body ground	9 to 14 V

   NG: Go to step 4 

   Fig 3: Inspecting ECM (HT1A Voltage)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   OK: REPLACE ECM 

4. CHECK WIRE HARNESS (AIR FUEL RATIO SENSOR - ECM, AIR FUEL RATIO SENSOR EFI RELAY) 
   1. Check the wire harness between the ECM and A/F sensor.
      1. Disconnect the A3 A/F sensor connector.
      2. Disconnect the E8 ECM connector.
      3. Measure the resistance according to the value (s) in the table below.

         Standard resistance 

         WIRE HARNESS TESTER CONNECTION AND SPECIFIED CONDITION
         
         

         Tester Connection	Specified Condition
         HT (A3-1) - HA1A (E8-1)	Below 1 Ω
         HT (A3-1) or HA1A (E8-1) - Body ground	10 kΩ or higher

   2. Check the wire harness between the A/F sensor and EFI relay.
      1. Disconnect the A3 A/F sensor connector.
      2. Remove the EFI relay from the engine room relay block.
      3. Measure the resistance according to the value (s) in the table below.

         Standard resistance 

         WIRE HARNESS TESTER CONNECTION AND SPECIFIED CONDITION
         
         

         Tester Connection	Specified Condition
         +B (A3-2) - EFI relay (3)	Below 1 Ω
         +B (A3-2) or EFI relay (3) - Body ground	10 kΩ or higher

   NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

   Fig 4: Checking Wire Harness (Air Fuel Ratio Sensor - ECM, Air Fuel Ratio Sensor EFI Relay)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   OK: REPLACE ECM