Identifying Concerns - Audio System

^ Check for technical service bulletins. Check the dealer communication system for any applicable preliminary information for customer concerns.
^ Check for stored diagnostic trouble codes.
^ For reception concerns, determine if the station is obtainable in the customer's listening area.
^ In order to test for audio reception/noise, position the vehicle outside the building with the hood down.
^ Duplicate the customer's complaint before trying to diagnose the system. Test drive the vehicle with the customer. Afterward, test drive another similar model vehicle with a similar audio system. Compare the two test drives in order to determine whether the condition is abnormal.
^ Before diagnosing, identify the components, their features and the customer's complaint.
^ Determine whether any aftermarket equipment is installed in the vehicle. Disconnect any such aftermarket equipment and determine whether the customer's complaint still exists. Follow GM guidelines for installation of aftermarket components.
^ Perform the following steps in order to identify a noisy component:
1. Identify the ignition key switch position in which the noise appears. Examples of key switch positions include the following:
^ Accessory
^ Key ON with the engine not running
^ Key ON with the engine running

2. Remove the fuses one at a time until the complaint condition has been eliminated.
3. Mark the complaint fuses. Reinstall all of the fuses and circuit breakers.
4. Refer to Power Distribution and Fuse Block Details in Electrical Diagnosis in order to identify all systems and components powered by the complaint fuses. Power and Ground Distribution
5. Disconnect the components powered by the complaint fuses one at a time until the complaint condition has been eliminated and the noisy component has been identified.
6. Check the ground integrity of the component which caused the complaint.
^ An interference condition is NOT necessarily an audible noise.
^ Most noises can be found on weak stations near the low end of the band. These noises are considered a normal condition.
^ Ignition noise on the FM band could indicate a possible defective ignition system.
^ Noise or poor reception could be caused by any of the following:
- Malfunctioning or marginal components
- Malfunctioning or marginal relays
- Malfunctioning or marginal solenoids.