RESETTING LEARNED IDLE THROTTLE ANGLE OFFSET

SUBJECT: PROCEDURE FOR RESETTING THE LEARNED IDLE THROTTLE ANGLE OFFSET

Idle learn is used on 1990-1991 DeVilles, Fleetwoods, Eldorados, Sevilles, and Allantes during coast down to compensate for loss of air flow due to throttle body deposits. If the battery is disconnected for a service procedure or any other reason, the learned value for the idle throttle angle offset is lost. The reset procedure allows the idle learn routine to seek and retain the proper throttle angle for each particular throttle body condition. This decreases the potential for stalling during coast down.

Before performing the reset procedure all service procedures must be complete, and the engine must be running continuously for a minimum of 18 minutes on 1990 vehicles and 13 minutes on 1991 vehicles.

Vehicle Reset Procedure:

1. Place the vehicle transmission in drive with the brakes applied.

2. Place vehicle climate control in the OFF position and allow the engine to remain at IDLE for at least one minute.

3. Make sure the outside air temperature reading is at least 50 F. Place the vehicle climate control in the AUTO position, verify A/C clutch engagement, and allow the engine to remain at IDLE for at least one minute.

4. Place the transmission in PARK and turn off the ignition.

IMPORTANT: Because of the load differences on the engine with A/C on versus A/C off, it is very important that learning be allowed under both conditions.

A time of six minutes is added to each procedure that requires the battery to be disconnected. The August revision of the Labor Time Guide reflects this change.

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.