4.5L (maximum Isc Extension) Cadillac Brougham I

1. Check TPS adjustment. See «THROTTLE POSITION SENSOR (TPS) ADJUSTMENT»(ref-92294-S15689257712001033000000). With ignition on and engine off, fully extend the ISC motor. Using 2 jumper wires, apply positive battery voltage to terminal "D" and ground terminal "C". (Scheme 5)
2. Apply battery voltage to ISC motor until plunger reaches maximum travel and ratchets a few times. Observe ISC nose positions to determine maximum travel. Remove jumper wires.
3. With ISC at maximum extension, TPS parameter displayed should be 10.5-11.5 (1.05-1.15 volts). If parameter displayed is incorrect, adjust ILC plunger adjusting screw.
4. Disconnect all test equipment and plug in all harness connectors. Turn off ignition for at least 10 seconds. Start engine and check ISC motor for proper operation. After all connections have been made and system is restored to normal operation, codes must be cleared.

Scheme 5

Note. On 5.0L and 5.7L engines, idle speed is controlled by ECM and will normally vary. Idle speed adjustment is not normally required. The following adjustment is for minimum idle speed only.

Scheme 6

1. Pierce idle stop screw plug with an awl and remove it. (Scheme 6) With Idle Air Control (IAC) motor connected, ground diagnostic lead. Ground lead by installing jumper wire between terminals "A" and "B" in diagnostic connector. Disconnect distributor "Set Timing" connector.
2. Turn ignition on, but do not start engine. Wait 45 seconds. With ignition on, disconnect IAC connector.
3. Remove ground from diagnostic lead and start engine. Allow engine to go into "closed loop" mode. Adjust idle screw to specifications. See IDLE SPEED RPM table.
4. Turn ignition off and connect IAC motor. Check TPS adjustment. See THROTTLE POSITION SENSOR (TPS) ADJUSTMENT. Start engine and check for proper idle operation.

IDLE SPEED RPM