GM Service Manual Online
For 1990-2009 cars only

NO START/NO SPARK CONDITION FAILURE DIAGNOSIS

WHEN DIAGNOSING A NO START/NO SPARK CONDITION ON C3I IGNITION SYSTEMS, MAKE SURE THE C3I IGNITION MODULE IS BOLTED TO ITS MOUNTING BRACKET. FAILURE TO BOLT THE MODULE TO ITS BRACKET ELIMINATES THE MODULE'S PATH TO GROUND. THE MODULE MUST BE PROPERLY GROUNDED IN ORDER TO CONTINUE DIAGNOSTICS AND KEEP FROM REPLACING GOOD MODULES.

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.