Contents: Examination ↓ Replacement ↓
Idle speed control valve (ISC valve, on cars 1988-92.) or idle air control valve (IAC valve, on cars since 1993.).
Attention! The engine idle speed is set by the manufacturer and does not require adjustment under normal operating conditions. However, if the throttle chamber has been replaced or there is a suspicion that the idle speed adjustment has been violated (for example, the idle speed screw was unscrewed from the throttle chamber), then the car should be taken to a car service center.
Examination
1. When the ignition is turned off, the idle speed control valve (ISC valve) should make a clicking sound.
2. Disconnect the ISC valve connector.
3. Apply voltage to terminals B1 and B2 using a jumper. Connect terminals S1 and S2 to ground, then S3 and S4. The valve plunger should extend, i.e. the valve should close.
4. Apply voltage to terminals B1 and B2 using a jumper. Connect terminals S3 and S4 to ground, then S1 and S2. The valve plunger should retract, i.e. the valve should open.
5. If the valve does not work, replace it.
6. Check the resistance between terminals B1 and S1, B1 and S3, then between terminals B2 and S2, B2 and S4. Compare the results with those specified in the technical data (see subsection 5.2.1).
7. If the resistance is normal, then the valve is working properly (in this case, you should look for a fault in the wiring from the ECM unit).
8. If the resistance differs from the standard, replace the valve.
9. Connect the connector.
Replacement
1. If access to the screws is difficult, remove the damper housing.
2. Loosen the mounting screws (indicated by arrows) ISC valves (or IAC valves) to the valve body and remove the valve.
3. When replacing the valve, install the thermal vacuum TVV valve removed from the ISC valve being replaced and replace the gasket.
4. Installation is carried out in reverse order.