For 1990-2009 cars

# AUDIBLE BACKGROUND TONE IN A.M.RADIO BAND

#### VEHICLES AFFECTED: All 1984 And Some Early 1985 Models With Radio And Electronic Cruise Control (K34)

An audible background tone usually in the area of 1000 to 1300 on the AM radio band may be noted on some cars. If the tone only occurs with the cruise slide switch in the 'on' position, the cause could be in the cruise module.

This condition may be easily diagnosed by turning the ignition to the 'on' position (car not running), move the cruise slide switch to the 'on' position and tune the radio to obtain the interference tone. Once the tone is obtained, if it can be eliminated by moving the cruise slide switch to the 'off' position, the problem is in the cruise module. Replace the cruise module with a new one with a date code later than 3/1/84. The date code can be found stamped on the label of the cruise module (See Figure 1).

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.