For 1990-2009 cars

# ALTERNATOR WHINE-LEFT CHANNEL MODIFY GROUND TO RADIO

#### MODELS AFFECTED: 1985, 1986 DE VILLE, FLEETWOOD, AND CIMARRON (EXCEPT VEHICLES EQUIPPED WITH DELCO-BOSE)

Some late 1985 and early 1986 De Villes, Fleetwoods and Cimarrons built between April, 1985 and shortly after the start of the 1986 production may exhibit a radio noise, primarily in the left channel speakers, which is induced by the alternator. Cars built with the optional Delco-Bose premium sound system are not affected. The condition is evident even with low alternator electrical loads, and the level of noise does not change when the radio volume is changed. The audio circuits in these radios may be susceptible to picking up the noise if a marginal radio ground circuit exists. After the start of production 1986 the radio circuitry was changed to eliminate this susceptibility.

Cars exhibiting this type of radio noise can be repaired by revising the radio ground circuit as follows:

1. Cut or remove the black ground lead from the black connector at the rear of the radio.

2. Install a ring terminal on to the previously removed ground wire and reconnect ground wire to the radio case using an existing radio case screw.

#### IMPORTANT: A parallel ground to the radio case will not correct the condition. The ground wire in the black connector must be disconnected from the radio ground terminal.

For warranty purposes use labor operation T-6136 for .3 hours to complete the above repair.

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.