Idle Speed Control (ISC) Adjustment

Fig. 27 Idle Speed Control (ISC) motor test connections. E2SE Carburetor:

Fig. 28 Idle Speed Control (ISC) motor adjustment specifications. E2SE Carburetor:

NOTE: Do not use ISC plunger to adjust curb idle speed, as idle speed is controlled by the Electronic Control Module (ECM). When a new ISC is installed, or when indicated by the "System Performance Check", a base (minimum authority) and a high (maximum authority) RPM check must be made, and adjustments performed as needed. When making low and high speed adjustments, low speed adjustment must be performed first.

1. Connect dwell meter to test lead in MC solenoid harness (usually a green wire) and set meter on 6 cylinder scale. Connect tachometer to engine following manufacture's instructions.
2. Start engine and run at fast idle until it reaches normal operating temperature and dwell reading begins to fluctuate.
3. Stop engine and disconnect wiring harness connector to ISC motor.

NOTE: Do not connect or disconnect wiring harness connector to ISC motor with ignition in on position, as ECM will be damaged.

4. Using a jumper wire, connect battery voltage to terminal "C" on ISC motor, FIG 27, then connect a jumper wire between terminal "D" and ground.

NOTE: Do not leave battery voltage connected to ISC motor longer than necessary to retract solenoid plunger. Do not connect battery voltage to terminals "A or B" on motor. ISC motor will be damaged if connections are improperly made.

5. Start engine and run until dwell reading begins to fluctuate. Place transmission in drive (manual transmission in neutral).
6. With ISC plunger fully retracted, adjust idle speed to specified minimum authority RPM, FIG 28, with throttle stop screw.
7. Place transmission on neutral and reverse jumper wire connections. Connect battery voltage to terminal "D", and connect terminal "C" to ground.

NOTE: Leave jumper wires connected only long enough to fully extend ISC plunger.

8. With plunger fully extended, adjust idle speed to specified maximum authority RPM, Fig 28, by turning ISC plunger with tool J-29607 or equivalent.

NOTE: Adjustments must be made as quickly as possible. If engine RPM increases, adjustment cannot be performed, engine will have to be stopped and the procedure will have to be restarted from step 2.

9. Stop engine. Reconnect wiring harness connector to ISC motor.

NOTE: Test connections to ISC motor will cause "Check Engine" light to remain on until wiring harness is reconnected to motor. An intermittent trouble code will then be stored in the ECM memory which must be cleared.