Inspection Procedure

HINT:

Hand-held tester only:

It is possible the malfunctioning area can be found using the ACTIVE TEST A/F CONTROL operation. The A/F CONTROL operation can determine if the A/F sensor, heated oxygen sensor or other potential trouble areas are malfunctioning or not.

1. Perform the ACTIVE TEST A/F CONTROL operation.

   HINT:

   The A/F CONTROL operation lowers the injection volume 12.5 % or increases the injection volume 25 %.

   1. Connect the hand-held tester to the DLC3 on the vehicle.
   2. Turn the ignition switch ON.
   3. Warm up the engine by running the engine at 2,500 rpm for approximately 90 seconds.
   4. Enter the following menus: DIAGNOSIS/ENHANCED OBD II/ACTIVE TEST/A/F CONTROL.
   5. Perform the A/F CONTROL operation with the engine idle (press the right or left button).

   Result: 

   A/F sensor reacts in accordance with increase and decrease of injection volume: 

   +25 % --> RICH output: Less than 3.0 V 

   -12.5 % --> LEAN output: More than 3.35 V 

   Heated oxygen sensor reacts in accordance with increase and decrease of injection volume: 

   +25 % --> RICH output: More than 0.55 V 

   -12.5 % --> LEAN output: Less than 0.4 V 

   NOTE: The A/F sensor output has a few seconds of delay and the heated oxygen sensor output has about 20 seconds of delay at maximum.
   Fig 1: Active Test Result Chart

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   The following A/F CONTROL procedure enables a technician to check and graph the voltage outputs of both the A/F sensor and the heated oxygen sensor.

   For displaying the graph, enter "ACTIVE TEST/A/F CONTROL/USER DATA", select "AFS B1S1 and O2S B1S2" by pressing "YES" and push "ENTER". Then press "F4".

   HINT:

   • If DTC P2237, P2238, P2239, P2251, P2252 or P2253 is displayed, check the bank 1 sensor 1 circuit.
   • Read freeze frame data using the hand-held tester or the OBD II scan tool. Freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, 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 A6 A/F sensor connector.
   2. Measure the resistance of the A/F sensor terminals.
      Fig 2: Identifying Air Fuel Ratio Sensor Connector Terminals

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard: 

      TESTER CONNECTION AND CONDITION SPECIFICATIONS
      
      

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

   1. NG: REPLACE AIR FUEL RATIO SENSOR 
   2. OK: GO TO NEXT STEP. 
2. INSPECT RELAY (EFI) 
   1. Remove the EFI relay from the engine room J/B.
   2. Measure the resistance of the EFI relay.
      Fig 3: Identifying EFI Relay Terminals

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard: 

      TESTER CONNECTION AND CONDITION SPECIFICATIONS
      
      

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

   1. NG: REPLACE RELAY 
   2. OK: GO TO NEXT STEP. 
3. CHECK WIRE HARNESS (A/F SENSOR - ECM) 
   1. Check the wire harness between the ECM and A/F sensor.
      1. Disconnect the A6 A/F sensor connector.
      2. Disconnect the E8 ECM connector.
      3. Measure the resistance of the wire harness side connectors.
      Fig 4: Identifying A/F Sensor & ECM Connector Terminals
      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard: 

      Fig 5: Harness Resistance Values

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      Fig 6: A/F Sensor And EFI Relay Circuit Diagram

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   1. NG: REPAIR OR REPLACE HARNESS AND CONNECTOR 
   2. OK: REPLACE ECM (See  REPLACEMENT  )