Inspection Procedure

HINT:

Read freeze frame data using a Techstream. Freeze frame data record the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data, from the time the malfunction occurred.

1. INSPECT AIR-FUEL RATIO SENSOR (HEATER RESISTANCE) 
   1. Disconnect the C23 A/F sensor connector.
   Fig 1: Identifying A/F Sensor Connector Terminals
   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   2. Measure the resistance of the A/F sensor connector.

      Standard resistance 

      TESTER CONNECTIONS SPECIFIED CONDITIONS CHART
      
      

      Tester Connections	Specified Conditions
      HA1A (1) - +B (2)	1.8 Ω to 3.4 Ω at 20°C (68°F)
      HA1A(1) - A1A- (4)	10 kΩ or higher

   3. Reconnect the A/F sensor connector.

   NG: REPLACE AIR-FUEL RATIO SENSOR  (See REMOVAL )

   OK: Go to next step 

2. CHECK TERMINAL VOLTAGE (+B OF A/F SENSOR) 
   1. Disconnect the C23 A/F sensor connector.
   Fig 2: Identifying C23 A/F Sensor Connector Terminals
   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   2. Turn the ignition switch to ON.
   3. Measure the voltage between the terminals of the C23 A/F sensor connector and body ground.

      Standard voltage 

      TESTER CONNECTIONS SPECIFIED CONDITIONS CHART
      
      

      Tester Connections	Specified Conditions
      +B (C23-2) - Body ground	11 to 14 V

   4. Reconnect the A/F sensor connector.

   OK:  Go to step  5

   NG: Go to next step 

3. INSPECT INTEGRATION RELAY (EFI RELAY) 
   1. Remove the integration relay from the engine room relay block.
   2. Inspect the EFI fuse.
      1. Remove the EFI fuse from the integration relay.
      2. Measure the EFI fuse resistance.

         Standard resistance: 

         Below 1 Ω 

      3. Reinstall the EFI fuse.
   3. Inspect the EFI relay.
      1. Measure the EFI relay resistance.

         Standard resistance 

         TESTER CONNECTIONS SPECIFIED CONDITIONS CHART
         
         

         Tester Connections	Specified Conditions
         1C-1 - 1A-4	10 kΩ or higher
         	Below 1 Ω (Apply battery voltage between terminals 1A-2 and 1A-3)

         Fig 3: Identifying Integration Relay (EFI Relay)

         Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   4. Reinstall the integration relay.

   NG: REPLACE INTEGRATION RELAY 

   OK: Go to next step 

4. CHECK HARNESS AND CONNECTOR (A/F SENSOR - EFI RELAY) 
   1. Disconnect the C23 A/F sensor connector.
   Fig 4: Identifying Harness And Connector (A/F Sensor - EFI Relay)
   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   2. Remove the integration relay from the engine room Relay Block (R/B).
   3. Check the resistance.

      Standard resistance (Check for open) 

      TESTER CONNECTIONS SPECIFIED CONDITIONS CHART
      
      

      Tester Connections	Specified Conditions
      +B (C23-2) - Engine room R/B (1A-4)	Below 1 Ω

      Standard resistance (Check for short) 

      TESTER CONNECTIONS SPECIFIED CONDITIONS CHART
      
      

      Tester Connections	Specified Conditions
      +B (C23-2) or Engine room R/B (1A-4) - Body ground	10 kΩ or higher

   4. Reconnect the A/F sensor connector.
   5. Reinstall the integration relay.

   NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

   OK: CHECK ECM POWER SOURCE CIRCUIT (See  ECM POWER SOURCE CIRCUIT   ) 

5. CHECK HARNESS AND CONNECTOR (A/F SENSOR - ECM) 
   1. Disconnect the C23 A/F sensor connector.
   Fig 5: Identifying C23 A/F Sensor And C20 ECM Connectors Terminals
   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   2. Disconnect the C20 ECM connector.
   3. Check the resistance.

      Standard resistance (Check for open) 

      TESTER CONNECTIONS SPECIFIED CONDITIONS CHART
      
      

      Tester Connections	Specified Conditions
      HA1A (C23-1) - HA1A (C20-109)	Below 1 Ω

      Standard resistance (Check for short) 

      TESTER CONNECTIONS SPECIFIED CONDITIONS CHART
      
      

      Tester Connections	Specified Conditions
      HA1A (C23-1) or HA1A (C20-109) - Body ground	10 kΩ or higher

   4. Reconnect the A/F sensor connector.
   5. Reconnect the ECM connector.

   NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

   OK: Go to next step 

6. CHECK WHETHER DTC OUTPUT RECURS (DTC P0031 OR P0032) 
   1. Connect the Techstream to the DLC3.
   2. Turn the ignition switch to ON.
   3. Turn the tester ON.
   4. Clear DTCs (See DTC CHECK/CLEAR  ).
   5. Start the engine.
   6. Allow the engine to idle for 1 minute or more.
   7. Select the following menu items: Powertrain / Engine and ECT / Trouble Codes.
   8. Read DTCs.

      Result 

      RESULT CHART
      
      

      Display (DTC Output)	Proceed To
      No output	A
      P0031 or P0032	B

   B: REPLACE ECM (See  REMOVAL   ) 

   A: CHECK FOR INTERMITTENT PROBLEMS (See  CHECK FOR INTERMITTENT PROBLEMS   )