Inspection Procedure

HINT:

Read freeze frame data using the hand-test 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, etc at the time of the malfunction occurred.

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

   PREPARATION: 

   1. Connect the OBD II scan tool or hand-held tester to the DLC3.
   2. Turn the ignition switch ON and push the OBD II scan tool or hand-held tester main switch ON.
   3. Start the engine.
   4. When using hand-held tester, 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: 

   Fig 1: Mass Air Flow Rate Chart

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   1. B: Go to step   6 . 
   2. C: Check for intermittent problems (See  PRE-CHECK   ). 
   3. A: Go to next step. 
2. Check voltage of mass air flow meter power source. 

   PREPARATION: 

   1. Check voltage of mass air flow meter power source.
   2. Turn the ignition switch ON.

   CHECK: 

   Measure the voltage between terminal 3 of the mass air flow meter connector and body ground.

   Fig 2: Measuring Voltage Between Terminal 3 Of Mass Air Flow Meter Connector & Body Ground

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   OK: 

   voltage: 9 to 14 

   1. NG: Go to step   5 . 
   2. OK: Go to next step. 
3. Check voltage between terminal VG of ECM connector and body ground. 

   PREPARATION: 

   1. Remove the ECM hood (See ENGINE CONTROL MODULE (ECM) .)
   2. Start the engine.

   CHECK: 

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

   Fig 3: Measuring Voltage Between Terminal VG Of ECM Connector & Body Ground

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   OK: 

   voltage: 

   1.1 to 1.5 V (P or N position and A/C switch OFF) 

   1. OK: Replace ECM (See  HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE  ). 
   2. NG: Go to next step. 
4. Check for open and short in harness and connector between mass air flow meter and ECM (See  HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE  ). 
   1. NG: Repair or replace harness or connector. 
   2. OK: Replace mass air flow meter. 
5. Check for open and short in harness and connector between mass air flow meter and ECM (See  HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE  ). 
   1. NG: Repair or replace harness or connector. 
   2. OK: Check ECM power source circuit (See  ECM Power Source Circuit   ). 
6. Check continuity between terminal EVG of ECM connector and body ground. 

   PREPARATION: 

   Remove the ECM hood (See ENGINE CONTROL MODULE (ECM) )

   CHECK: 

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

   Fig 4: Checking Continuity Between Terminal EVG Of ECM Connector & Body Ground

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   OK: 

   Continuity (1 Ω or less) 

   1. NG: Replace ECM (See  HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE  ). 
   2. OK: Go to next step. 
7. Check for open and in harness and connector between mass air flow meter and ECM (See  HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE  ). 
   1. NG: Repair or replace harness or connector. 
   2. OK: Replace mass air flow meter.