- Warm engine to normal operating temperature. Turn A/C and all accessories off. Enter diagnostics and select Powertrain Control Module (PCM) override ES03, Idle Speed Control (ISC) motor. See ENTERING SELF-DIAGNOSTICS in G - TESTS W/ CODES article in this section.
- This action disengages the A/C compressor, command EGR off and turn off alternator. The Electronic Climate Control (ECC) panel will display 50 to 00. The ISC motor will slowly move to a fully retracted position (20 seconds).
- Ensure throttle lever is resting on the minimum idle speed screw. With ISC plunger fully retracted, disconnect ISC harness. The plunger should not be touching the throttle lever. If contact is noted, adjust ISC plunger.
- If engine stalls, check throttle blades for deposits that might restrict airflow. Clean throttle bores and area behind and around throttle plates. Check minimum idle speed displayed on Driver Information Center (DIC). Use average RPM reading to set minimum idle speed. See MINIMUM IDLE SPEED (V8 - 4.9L) table. Check for vacuum leaks.
| Application | Idle Speed (RPM) |
|---|---|
| DeVille, Eldorado, Fleetwood & Seville | 500-550 |
MINIMUM IDLE SPEED
Note. On 5.0L (VIN E & F) and 5.7L (VIN 7 & 8) engines, idle speed is controlled by ECM and will normally vary; adjustment is normally not required. The following adjustment is for minimum idle speed only.