For 1990-2009 cars

# POOR IDLE/(CODE 30 CAD. ONLY) ISC ASSEMBLY REPAIR KIT

1981-1982 IDLE SPEED CONTROL ASSEMBLY

Idle Speed Control (ISC) assemblies with plungers that do not extend or retract properly may cause erratic idle speed fluctuations and/or set a code 30 on DFI-equipped vehicles. A revised ISC assembly which uses a new gear and shaft was released to correct this condition during 1982 production. It may be identified by a yellow dot on the housing. Before replacing an ISC assembly without a yellow dot, diagnose the condition as follows:

1. Use self-diagnostics and the appropriate diagnostic trouble tree to test the system to determine that the ISC assembly is the cause.

- 1981 DFI - Follow chart for code 30 on page A-51 of the 1981 Cadillac Digital Fuel Injection and Computer Command Control Diagnosis Manual Supplement.

- 1982 HT4100 DFI - Follow chart for code 30 on page 8D1-51 of the 1982 Electrical Information and Diagnosis Manual - Final Update (replaces 1982 looseleaf Service Manual and contains all revisions).

- 1982 4.1L V-6 - Follow ISC check chart on page 8D2-37 of the 1982 Electrical Information and Diagnosis Manual - Final Update.

- 1982 Cimarron 1.8L - Follow ISC check chart on page 6E-38 of the 1982 Cimarron Service Information Manual.

2. If the systematic diagnosis using the trouble trees indicates the ISC is the cause and should be replaced, determine whether to repair or replace the ISC assembly as follows.

3. Enter ISC cycling diagnostics (96 or .9.6 series on DFI vehicles or ground diagnostic terminal with engine not running on CCC-equipped vehicles).

4. Determine if ISC motor is running during ISC cycling diagnostics by observing any of the following:

- ISC motor can be heard to be running. - ISC plunger moves, but does not move in and out smoothly. - Vibrations from the ISC motor running and reversing can be felt.

5. If the ISC motor does not run, the ISC assembly must be replaced. If the ISC motor does run but the plunger does not move properly, repair the ISC assembly as described below.

Two separate service repair packages have been released to repair 1981-1982 ISC assemblies prior to the production change. Applications are as follows:

GMWDD SERVICE KIT PART NUMBER APPLICATION ----------- ------------ 17079749 1.8L L4 J

17079750 6.0L V8 C,D,E,K HT4100 V8 C,E,K 4.1L V6 Q,E,K

The repair kits contain a gear, shaft assembly, boot, grease and an instruction sheet for rebuilding.

For warranty purposes, use labor Operation No. J6346, "ISC Motor - R&R or Replace," at .5 hour. ADD: To recondition .3 hour.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.