Idle Speed: Testing and Inspection

Fig. 3 Checking current supply:

Before performing tests, ensure that engine is in good operating condition and that ignition timing is within specifications. Perform tests only when engine is at normal operating temperature. Turn engine off before disconnecting connectors.
1. Check connectors as follows:
a. Remove right front kick panel in passenger compartment and ensure that connectors are connected at continuous idle speed system electronic control unit, blue connector at top and black connector at bottom.
b. Ensure that two connectors at firewall are connected.
c. Ensure that air control valve electrical connector is connected.
2. If engine idle speed is considerably below specifications, proceed as follows:
a. Check air hoses for obstructions.
b. Check air control valve for sticking or obstruction.
c. If air control valve is stuck or obstructed, clean PCV system.
3. Disconnect electrical connectors at constant idle speed system electronic control unit, then turn ignition switch to ``On'' position.
4. Connect suitable voltmeter across terminals 1 (+) and 2 (-), Fig. 3. If voltmeter does not read battery voltage, check alternate ground, then fuse No. 13.

Fig. 4 Checking throttle switch:

5. Connect ohmmeter across blue connector terminal 8 and ground, Fig. 4. If ohmmeter does not read infinite ohms, adjust throttle switch.

Fig. 5 Checking coolant temperature sensor:

Fig. 6 Coolant temperature sensor resistance/temperature specification chart:

6. Connect ohmmeter across terminals 9 and 11 of blue connector, Fig. 5. If resistance reading is not within specifications, Fig. 6, replace coolant temperature sensor.

Fig. 7 Checking ignition system signal:

Fig. 8 Checking air control valve:

7. Connect tachometer across terminal 12 and ground, Fig. 7, then start engine. If tachometer does not read engine speed, recheck connectors on firewall.
8. Connect a jumper wire across terminals 1 and 4 and a second jumper wire across terminals 2 and 5, Fig. 8, then start engine. If idle speed does not increase to 1600-2400 RPM, replace air control valve.
9. If, after replacing air control valve, idle speed is not 1600-2400 RPM, electronic control unit is probably defective.
10. Connect connectors at control unit, check connectors as described in step 1, and check operation of Constant Idle Speed system.