Initial Inspection and Diagnostic Overview

START DIAGNOSTICS HERE
Perform the checks listed below before beginning System Diagnosis.

1. Test Radio outside of building with hood down.

2. Most noise can be found on weak AM stations near the low frequency end of the band.

3. Ignition noise on FM indicates a possible defective HEI system.

4. If a test antenna is used, ground the base of the test antenna to the vehicle body. DO NOT hold the mast of the antenna.

5. Coated screws or bolts can act as a poor ground.

6. Most hoses are conductive unless they have a white stripe.

7. When shielding components, use aluminum foil tape and ground BOTH ends of the shield.

8. Any noise is best corrected by suppression at the source of the noise.

9. Power lines, bridges, buildings, etc., can block AM reception.

10. FM reception can be affected by atmospheric conditions, terrain, large buildings and the strength of the transmitter.

^ Check for a broken (or partially broken) wire inside of the insulation which could cause system malfunction but prove "GOOD" in a continuity or voltage check with a system disconnected. These circuits may be intermittent or resistive when loaded, and if possible, should be checked by monitoring for a voltage drop with the system operational (under load).

^ Check for proper installation of aftermarket electronic equipment which may affect the integrity of other systems.

SYSTEM DIAGNOSIS
^ Refer to the Symptom Table for the appropriate diagnostic procedure(s).

^ A noise "sniffer" may be used to aid in troubleshooting Radio noise. Refer to Using a Noise Sniffer.