INOPERATIVE QUARTZ ELECTRIC SPEEDOMETER (DIAGNOSIS)

VEHICLES AFFECTED: 1985-1986 Oldsmobile Calais Equipped with Standard Quartz Speedometer and U21

An inoperative speedometer may be due to a non-functioning diode and/or integrated circuit. If this condition is suspected the following checks should be made prior to installing a replacement.

The trip odometer stepper motor wires should be inspected for proper positioning where they enter the motor. The wires should be positioned to prevent them from being pinched between the motor and I.P. carier. Refer to Fig. 1. The instrument panel carrier may also be modified if necessary to provide clearance. Refer to Fig. 2.

Vehicles Equipped With Standard Quartz Speedometer and V-6 Engine.

If printed circuit foils number 6 and/or 10 (from cluster connector 2) are 'burnt' the printed circuit must be replaced. If this condition exists, a possible cause may be the yellow or purple VSS wire shorting to the pink/brown battery voltage wire (circuit 39) at the power steering return hose clamp at the power steering pump. Wires should be repaired and repositioned as necessary.

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.