For 1990-2009 cars

# INOP RADIO/CLOCK DISPLAY DIAGNOSTIC PROCEDURE

#### VEHICLES AFFECTED: 1984 'E' and Pontiac 6000 STE Models 1985 'C' Models

Some models equipped with cassette tape decks may experience a condition of an inoperative radio and/or erratic clock display along with normal unaffected tape deck performance. This condition may be caused by an electrostatic discharge inside the receiver. Vehicles operated in areas of low humidity increase the possibility of this condition occurring. For this condition to occur, the tape unit must be in use and the tape search feature activated. If a sufficient static electricity charge is generated, it can discharge through the receiver microprocessor causing the radio and/or clock display to be inoperative. The tape deck operation does not depend on the microprocessor and will remain operational after this condition occurs. This temporary disablement of the receiver microprocessor can be reversed by removing all voltage from the radio receiver, however, the unit should be removed and sent to an authorized Delco Repair shop for correction to prevent this condition from recurring.

To diagnose if an electrostatic discharge is the cause of the inoperative radio and/or erratic clock display, the following test should be used.

1. Verify that the AM and FM bands of the receiver do not operate and that the cassette tape deck does operate correctly.

2. Remove power to the radio for a minimum of 10 seconds by either disconnecting and reconnecting the negative battery cable with key off or removing and reinstalling the clock fuse.

3. Retest for AM and FM operation. If the radio now operates, the electrostatic discharge condition has occurred. To prevent this condition from recurring, the receiver must be removed and sent to a Delco Repair Shop along with a claim tag indicating that it was disabled by an electrostatic discharge.

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.