This bulletin applies to 1984-1988 5.OL (VIN H/G) and 5.7L (VIN 6) "B," "F," and "G" Carline Service Manuals. In DRIVEABILITY AND EMISSIONS (SECTION 6E1) the ECM Wiring Diagrams may illustrate that the 439 (ignition feed) circuit is spliced to circuit 437 (vehicle speed sensor). Ignition voltage is not supplied to, nor is circuit 439 spliced to the vehicle speed sensor circuit (437).
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.