buick Workshop Repair Guides

Buick Workshop Service and Repair Manuals

Relays and Modules - Emission Control Systems > < Chart C-2A Idle Speed Control (ISC) Check|Page 1327
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relay which has two sets of contacts. Control of the relay is by the ECM which completes a ground to energize the solenoid. When energized, idle is
increased only if A/C is "ON". When de-energized throttle opening is increased regardless of A/C position.

1.

Checks for normal operation of solenoid. With key "ON" engine not running solenoid plunger should extend.

2.

Checks for normal solenoid plunger retraction if "test" terminal is grounded.

Relays and Modules - Emission Control Systems > < Chart C-2A Idle Speed Control (ISC) Check|Page 1327