Some 1986 Eldorados and Sevilles may experience erratic relay operation and/or flashing interior and exterior lighting with the ignition in the "RUN" position possibly accompanied by codes B334, B335, B336, B337, B446, B447, B448, B660 or B663. This condition may be caused by an inoperative BCM PROM. BCM PROM's that may cause this condition can be identified by a white stripe or the manufacturer's code, 014, on the PROM (see Figure 1).
To correct this condition, replace the BCM PROM with P/N 16068128. Check replacement PROM's to be sure that they do not have a white strip or a manufacturer's code 014,
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.