Tools - Idle Air Control (IAC) Driver Service

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Number: 90-105-6E

Section: 6E

Date: December 1989

Corporate Bulletin No.: 916531


Subject:
IAC DRIVER TOOL


Model and Year:
1987-90 A, J, L CARS 1990 W CAR


TO: ALL CHEVROLET DEALERS

This bulletin is to inform General Motors Dealer Technicians using the Idle Air Control (IAC) Driver Tool "Special Tool" Number (22M - Concept Technology) or (J 37027 - Kent Moore) on all 2.8L/3.1 L MPFI engines that the Diagnostic Test Terminal must be grounded or Field Service Mode entered if a "Scan Tool" is used.

The grounding procedure is fully explained in the diagnostic charts for Service Manual Sections "6E3-A" (Code 35) and "6E3-C2" (Idle Air Control (IAC) Circuit). However, the grounding procedure must also be followed when using the tool for other uses such as:
Idle (RPM) Control, Generator Diagnosis, A/C Recharging, etc.

The engine carlines involved are as follows:
1990 "W" Carline
1989-1990 "A. J. L." Carlines
1988 "J" Carline
1987-1988 "A. L" Mass Air Flow to Speed Density Updates
1987 "J" Mass Air Flow to Speed Density Updates

It should also be noted that whenever the IAC system is disconnected or a battery disconnect is made, the "Idle Learn Procedure" in Section "6E3-C2" of the Service Manual should be followed.