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, as well as other data from the time when a 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. Turn ignition switch ON and push the hand-held tester or the OBD II scan tool main switch ON.
   3. Start the engine.
   4. When using the hand-held tester, enter the following menus: DIAGNOSIS/ENHANCED OBD I I/DATA LIST/ALL/MAF.

   CHECK: 

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

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

   CHECK: 

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

   OK: 

   1. Voltage: 9 to 14 V 
   Fig 2: Measuring Voltage Between Mass Air Flow Meter Connector & Body Ground

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   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 cover.
   2. Start the engine.

   CHECK: 

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

   OK: 

   1. Voltage: 
   2. 1.1 to 1.5 V (P or N position and A/C switch OFF) 
   1. OK : Replace ECM (See  ENGINE CONTROL MODULE (ECM)  ). 
   2. NG : Go To Next Step. 
   Fig 3: Locating ECM VG Terminal

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
4. Check for open and short in harness and connector between mass air flow meter and ECM (See  PROCEDURE  ). 
   1. NG : Repair or replace harness and connector. 
   2. OK : Replace mass air flow meter. 
5. Check for open and short in harness and connector between mass air flow meter and EFI relay (See  PROCEDURE  ). 
   1. NG : Repair or replace harness and 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 cover.

   CHECK: 

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

   OK: 

   1. Below 1 Ω 
   Fig 4: Locating ECM EVG Terminal

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   1. NG : Replace ECM (See  ENGINE CONTROL MODULE (ECM)  ). 
   2. OK : Go To Next Step 
7. Check for open in harness and connector between mass air flow meter and ECM (See  PROCEDURE  ). 
   1. NG : Repair or replace harness and connector. 
   2. OK : Replace mass air flow meter.