THIS BULLETIN CANCELS AND SUPERSEDES DEALER SERVICE BULLETIN NO. 90-143-7A. THE ARTWORK HAS BEEN REVISED. ALL COPIES OF 90-143-7A SHOULD BE DISCARDED.
This bulletin covers revised Wiring Diagram Information and eight 1990 HYDRA-MATIC 3T40 models added after the printing of the 1990 Service Manuals. (See Figures 1 thru 6.)
Currently some of the 1990 Service Manual wiring diagrams reference terminal path D "TO EGR SOL." This has been changed to "TO ECM" whenever referenced in the wiring diagrams. EGR SOL means "Energize Solenoid," not "Exhaust Gas Recirculation Solenoid."
Refer to this bulletin whenever service to any 1990 wiring assembly is necessary. All other instructions and procedures are the same as published in the 1990 7A Section of your service manual.
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.