Inspection Procedure

HINT:

Read freeze frame data using a hand-held tester or OBD II scan tool. 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. Connect hand-held tester or OBD II scan tool, and read value of mass air flow rate. 

   PREPARATION: 

   1. Connect the hand-held tester or the OBD II scan tool to the DLC3.
   2. Start the engine.
   3. Turn the hand-held tester or the OBD II scan tool ON.
   4. Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL / MAF.

   CHECK: 

   Read the value.

   RESULT: 

   MASS AIR FLOW RATE - SPECIFICATION TABLE
   
   

   Mass Air Flow Rate (gm/s)	Proceed To
   0.0	A
   271.0 or more	B
   Between 1.0 and 270.0 ((1))	C
   (1) The value must be changed when the throttle valve is open or closed.

   • B: Go to step   6 . 
   • C: Check for intermittent problems (See  PRE-CHECK   ). 
   • A: Go to next step. 
2. Check voltage of mass air flow meter power source. 

   PREPARATION: 

   1. Disconnect the mass air flow meter connector.
   2. Turn the ignition switch to ON.

   CHECK: 

   Measure voltage between terminal 1 of the mass air flow meter connector and body ground.

   OK: Voltage: 9 to 14 V 

   Fig 1: Checking Voltage Or Mass Air Flow Meter Power Source

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   • NG: Go to step 5. 
   • OK: Go to next step. 
3. Check voltage between terminal VG of ECM connector and body ground. 

   PREPARATION: 

   1. Start the engine.

   CHECK: 

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

   OK: Voltage: 1.1 to 1.5 V (A/C switch OFF) 

   Fig 2: Checking Voltage Between Terminal VG And Body Ground

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   • OK: Replace ECM (See  ENGINE CONTROL MODULE (ECM)  ). 
   • NG: Go to next step. 
4. Check for open and short in harness and connectors between mass air flow meter and ECM (See  HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE  ). 
   • NG: Repair or replace harness or connector. 
   • OK: Replace mass air flow meter. 
5. Check for open and short in harness and connectors between mass air flow meter and EFI relay (See  HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE  ). 
   • NG: Repair or replace harness or connector. 
   • OK: Check ECM power source circuit (See  ECM POWER SOURCE CIRCUIT   ). 
6. Check resistance between terminal EVG of ECM connector and body ground. 

   CHECK: 

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

   OK: Below 1 Ω 

   Fig 3: Checking Resistance Between Terminal EVG And Body Ground

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   • NG: Replace ECM (See  ENGINE CONTROL MODULE (ECM)  ). 
   • OK: Go to next step. 
7. Check for open in harness and connectors between mass air flow meter and ECM (See  HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE  ). 
   • NG: Repair or replace harness or connector. 
   • OK: Replace mass air flow meter.