Initial Inspection and Diagnostic Overview

Checking Complaints About Car Radio System

Malfunctions in radio system
1. Check error and customer complaint.
2. Switch ignition off and remove ignition key.
3. Remove radio fuses (ignition and memory).
4. Wait approx. 3 minutes until all components are free of tension.
5. Insert fuses again.
6. Check error and customer complaint again.







Reduced sound quality in one or more loudspeakers

INFORMATION: Reduced sound quality may be accompanied by a humming noise.

1. Switch on the system and change the fader and balance setting on the radio.
2. Check the fault status.
3. Find out on which channels the problem occurs.







Remedying problems with the amplifier







Interference noises

INFORMATION:
- This procedure is designed to help you find out how the interference noise has entered the system.
- In the following subchapters, the various interference noises are differentiated.

The battery must be fully charged.
No charging unit may be connected.







Interference noises, checking cable connections

INFORMATION: Procedure for interference noises which enter the system via the audio connections.







Interference noises due to alternator







Interference noises due to engine

The following points should be checked first:

INFORMATION:
- Make sure that the battery connections are seated properly and that the ground connection is guaranteed.
- Check whether the ignition coils are loose or defective.
- Check the plug connections and supply lines for the ignition coils for damage.
- Check the ground connections on the engine.
- Check whether the correct spark plugs have been installed and that the electrode gap is OK.







Interference noise due to antenna

INFORMATION:
- Follow this test routine if the interference noises come from the antenna.
- As an experiment, it is worth making a comparison by inserting a rod antenna.







Interference noises due to power supply

INFORMATION: Use this test routine for interference noises which originate from the vehicle electrics.







Interference noises due to all loudspeakers

INFORMATION: The loudspeaker leads are twisted together as standard.







Electromagnetic compatibility (EMC) - Troubleshooting

INFORMATION: Check the complaint to make sure that the symptoms really exist.