For 1990-2009 cars

# BASE TIMING TEST TIMING PROCEDURE INFORMATION

BASE TIMING ON 1982 V8 GAS ENGINES (VIN 8, Y) IS CHECKED BY GROUNDING THE DIAGNOSTIC TEST TERMINAL. IT IS NOT CHECKED BY DISCONNECTING THE FOUR WIRE DISTRIBUTOR CONNECTOR. SETTING BASE TIMING WITH THE FOUR WIRE CONNECTOR DISCONNECTED WILL RESULT IN AN ERROR OF ABOUT +6F. THIS ADVANCED TIMING CONDITION MAY CAUSE SPARK KNOCK.

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.