For the 1990 model year, two variations of the right side electrical center exist. Early models have no letter/number identifications embossed on the electrical center. Later models have letter/number identifications embossed on the electrical center (See Figure).
The schematics and diagnostics were written assuming that no letter/number identifications were embossed on later model electrical center, therefore the letter/number identifications embossed on later model electrical centers will not match what is shown on the schematics or diagnostics. When diagnosing the applicable electrical systems, use the letter/number identifications shown in parenthesis (See Figure).
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.