Computers and Control Systems: Adjustments

NOTE: Adjustment of idle speed is usually not required. If idle speed is out of specification check and verify the operation of the idle speed control system. Refer to COMPUTERS AND CONTROL SYSTEMS.

1. Precondition the vehicle as follows:
a. Engine coolant temperature greater than 185° F.
b. Lights, electric cooling fan, and all electrical accessories off.
c. Transmission in neutral or park.
d. Steering wheel in the neutral position.
e. Ignition timing verified correct.

Engine Idle Speed Inspection:

2. Insert a paper clip in the idle speed connector.
3. Connect a tachometer to the inserted paper clip.

Self Diagnostic Connector:

4. Use a jumper wire to ground the self diagnosis/data transfer switching terminal of the diagnostic connector located inside the passenger compartment under the dash.

Ignition Timing Diagnostic Connector:

5. Use a jumper wire to ground the ignition timing adjustment terminal.
6. Verify Idle Speed.

Curb Idle Speed
700 ± 50 rpm.

Fig. 93 Idle Speed Adjustment Screw (SAS):

7. If the idle speed is NOT as specified, adjust the speed adjusting screw.
8. Stop the engine, disconnect jumper wires, remove tachometer and reinstall waterproof plug in the connector for ignition timing adjustment.
9. Start the engine and confirm that idling condition is normal.