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Electronic Spark Timing (Est) Advance System

WARNING: This page does not describe the selected car, but rather 35 other vehicles, including the 1990 Pontiac Sunbird, 1990 Pontiac Grand Prix, 1990 Pontiac Grand Am, 1990 Pontiac Firebird, and 1990 Pontiac Bonneville. However, it is still accessible from the selected car via links, so may be relevant.
  1. A malfunction in the EST circuit should set a related trouble code. Start engine and warm to operating temperature. On vehicles equipped with a manual transmission, increase engine speed to about 2000 RPM. On vehicle equipped with an automatic transmission, slightly increase idle speed.
  2. On all vehicles, ground "test" terminal "B" of ALDL. A noticeable change in engine speed should occur. If no change occurs, see DIAGNOSTIC CIRCUIT CHECK in BASIC TESTING article.