Inspection Procedure

1. If the hose is damaged, replace the vacuum hose assembly.
2. Check the air and vacuum hoses for looseness, disconnection and blockage.

Fig 1: Intake Air Control Valve Actuator Flow Diagram

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NG: REPAIR OR REPLACE VACUUM HOSES 

OK: Go to Next Step 

1. Start the engine.
2. Disconnect the vacuum hose from the air cleaner cap.
3. Check that an unconnected port located on the vacuum tank applies suction to your finger.

   OK: 

   Vacuum pressure exists 

4. Reconnect the vacuum hose.

Fig 2: Disconnecting Vacuum Hose From Air Cleaner Cap

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NG: CHECK AND REPLACE VACUUM SOURCE AND HOSES 

OK: Go to Next Step 

1. Connect the oscilloscope between terminals ACM and E1 of the ECM connectors.
2. Warm up the engine to normal operating temperature.
3. Turn the A/C switch on.
4. Measure the voltage between terminals ACM and E1 of the ECM connectors.

   Standard voltage 

   ECM TERMINALS VOLTAGE SPECIFICATION
   
   

   Condition	Voltage
   Shift position is D, and engine speed is 850 rpm or less	Pulse generation
   Shift position is D, and engine speed is 950 rpm or more	9 to 14 V
   Shift position Is P	9 to 14 V

Fig 3: ECM Oscilloscope Voltage Waveform Graph

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OK:  Go to step  6

NG: Go to Next Step 

1. Disconnect the VSV for ACM connector.
2. Measure the resistance between terminals 1 and 2.

   Standard resistance: 

   19 to 21 Ω at 20°C (68°F) 

3. Reconnect the VSV for ACM connector.

Fig 4: Identifying Duty Vacuum Switching Valve Connector Terminals

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NG: REPLACE DUTY VACUUM SWITCHING VALVE 

OK: Go to Next Step 

1. Check the wire harness between the VSV for ACM connector and the ECM connector.
   1. Disconnect the VSV for ACM connector.
   2. Disconnect the ECM connector.
   3. Measure the resistance according to the value(s) in the table below.

      Standard resistance (Check for open) 

      TESTER CONNECTION SPECIFIED CONDITION
      
      

      Tester Connections	Specified Conditions
      VSV for ACM (B15-2) - ACM (B45-3)	Below 1 Ω

      Standard resistance (Check for open) 

      TESTER CONNECTION SPECIFIED CONDITION
      
      

      Tester Connections	Specified Conditions
      VSV for ACM (B15-2) or ACM (B45-3) - Body ground	10 kΩ or higher

   4. Reconnect the ECM connector.
2. Check the wire harness between the VSV for ACM and the EFI relay.
   1. Remove the engine room junction block.
   2. Measure the resistance between the wire harness side connectors.

      Standard resistance (Check for open) 

      TESTER CONNECTION SPECIFIED CONDITION
      
      

      Tester Connections	Specified Conditions
      VSV for ACM (B15-1) - Engine room junction block (EFI relay) (1D-5)	Below 1 Ω

   3. Reconnect the VSV for ACM connector.
   4. Reinstall the engine room junction block.

Fig 5: Identifying Engine Room Junction Block And VSV For ACM Connector Terminals

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NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: REPLACE ECM 

1. Remove the VSV for ACM.
2. Check operation of the VSV for ACM when positive battery voltage is applied to the terminals of the VSV for ACM connector.

   Positive battery voltage is not applied: 

   The air from pipe G is flowing out through pipes E and H. 

   Positive battery voltage is applied: 

   The air from pipe F is flowing out through pipes E and H. 

3. Reinstall the VSV for ACM.

NG: REPLACE DUTY VACUUM SWITCHING VALVE 

OK: Go to Next Step 

Fig 6: Inspecting Duty Vacuum Switching Valve Operation

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1. Disconnect the vacuum hose from the front engine mount insulator.
2. Using a vacuum pump, apply vacuum of 80 kPa (600 mmHg, 25 in.Hg) and wait for 1 minute.
3. Check that there is no change in the needle movement of the vacuum pump gauge.
4. Check that there is no fluid leakage caused by a break in the diaphragm.

   OK: 

   Vacuum pressure exists 

5. Reconnect the vacuum hose.

Fig 7: Inspecting Engine Mounting Insulator Assembly Front

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NG: REPLACE ENGINE MOUNTING INSULATOR ASSEMBLY FRONT 

OK: SYSTEM OK