Inspection Procedure

HINT:

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. Connect hand-held tester or OBD II scan tool and read value of air flow rate. 

   PREPARATION: 

   1. Connect the hand-held tester or OBD II scan tool to the DLC3.
   2. Start the engine.
   3. Push the hand-held tester or the OBD II scan tool main switch ON.
   4. On the hand-held tester or the OBD II scan tool, enter the following menus: DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL / MAF.

   CHECK: 

   Read the mass air flow rate on the OBD II scan tool or the hand-held tester.

   RESULT: 

   MASS AIR FLOW RATE CHECK RESULT
   
   

   Air Flow Rate (gm/s)	Proceed to
   0.0	Type I
   271.0 or more	Type II
   Between 1 and 270.0 (1)	Type III
   (1) The value must be changed when the throttle valve is opened or closed.

   1. Type II : Go to step   5 . 
   2. Type III : Check for intermittent problems (see  PRE-CHECK   ). 
   3. Type I: Go to next step. 
2. Check voltage of MAF meter power source. 

   PREPARATION: 

   1. Disconnect the MAF meter connector.
   2. Turn the ignition switch ON.

   CHECK: 

   Measure the voltage between terminal 1 of the MAF meter connector and body ground.

   OK: 

   Voltage: 9 to 14 V 

   Fig 1: Locating MAF Meter Power Source Connector +B (+) Terminal

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   1. NG : Check for open in harness and connector between EFI main relay and MAF meter (see  HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE  in INTRODUCTION article).  
   2. OK : Go to next step. 
3. Check voltage between terminal VG and EVG of ECM connector. 

   PREPARATION: 

   1. Remove the glove compartment (see COMPONENTS ).
   2. Start the engine.

   CHECK: 

   Measure the voltage between terminal VG and EVG of the ECM connector while the engine is idling.

   OK: 

   Voltage: 

   0.5 to 3.0 V (Neutral position and A/C switch OFF) 

   Fig 2: Locating VG (+) And EVG (-) Connector Terminals Of ECM

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   1. OK : Replace ECM (see  COMPONENTS  ).  
   2. NG : Go to next step. 
4. Check for open and short in wire harness between MAF meter and ECM, and between the MAF meter and EFI main relay (see  HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE  in INTRODUCTION article).  
   1. NG : Repair or replace harness and connector. 
   2. OK : Replace MAF meter. 
5. Check resistance between terminal EVG of ECM connector and body ground. 

   PREPARATION: 

   Remove the glove compartment (see COMPONENTS ).

   CHECK: 

   Check the resistance between terminal EVG of the ECM connector and body ground.

   OK: 

   Resistance: Below 1 Ω 

   Fig 3: Locating EVG (-) Connector Terminal Of ECM

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   1. NG : Replace ECM (see  COMPONENTS  ).  
   2. OK : Go to next step. 
6. Check for open in wire harness between MAF meter and ECM (see  HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE  in INTRODUCTION article).  
   1. NG : Repair or replace harness and connector. 
   2. OK : Replace MAF meter.