Idle Control System Tests

Idle Control System Test (A/T only)

1. Start the engine and warm up to normal operating temperature, the cooling fans will come on.
2. Check the idle speed with the headlights, heater blower, rear window defogger, cooling fan and air conditioner OFF, and the shift lever in "P" or "N" position.

Idle speed should be: 730 ± 50 rpm

- If the specified idle speed is available, go on to step 4.
- If the specified idle speed is not available, go on to step 2.





3. Check that the frequency solenoid valve C is operating.

NOTE: It may be easier to determine if the valve is working by placing your hand on it.

The solenoid valve should be clicking on and off continuously.
- If the solenoid valve doesn't operate properly, go to output troubleshooting.





- If the solenoid valve operates properly, connect the throttle controller hose to a 3-way joint, with a vacuum gauge in-line, as shown.
- If there is vacuum, go on to step 3.
- If there is no vacuum, check the vacuum hose for proper connection and condition.





4. Disconnect the two vacuum hoses at idle boost throttle controller and check each for vacuum.

There should be no vacuum in both hoses.

- If there is no vacuum, go on to step 5.
- If there is vacuum at either hose, go to Output Troubleshooting for idle boost or A/C idle boost solenoid valve.

5. Check the idle speed in "D3" or "D4".

Idle speed should be: 730 ± 50 rpm

- If the specified idle speed is not available, disconnect the inner vacuum hose on the idle boost throttle controller and check for vacuum.





- If there is vacuum, first check the throttle valve for smooth operation, then replace the idle boost throttle controller and recheck.
- If there is no vacuum, go to Output Troubleshooting.
6. Check the idle speed with the A/C ON.

Idle speed should be: 750 ± 50 rpm





- If the specified idle speed is not available, disconnect the two vacuum hoses at idle boost throttle controller and check each for vacuum.

There should be vacuum in both hoses.

- If there is vacuum in both hoses, check idle speed/mixture.
- If there is no vacuum at the #21 vacuum hose, go to idle boost solenoid valve troubleshooting.
- If there is no vacuum at the outside hose, go to A/C idle boost solenoid valve troubleshooting.