These revisions are presented to clarify the diagnostic procedure for the C31 ignition system. These charts supercede the A-3 charts and C-4 charts in Section 6E3 of the 1986 and 1987 Chassis Service Manuals (Vol. 1). Also these charts replace any previous charts published in Service Guilds or Bulletins for the engines listed above.
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.