Noise Diagnosis

Note: The following describes the ways that noise may enter a sound system and general solutions. Refer to Symptom Table for specific symptoms and diagnosis. A Symptom Table

Noise Types
Frontway
Frontway noise is any noise which can by eliminated by unplugging the antenna from the back of the radio. This noise enters the radio through antenna coaxilal cable.

Causes:
Poor grounding of: the antenna, the radio, some electrical compnent or body parts.
Defective or marginal components: relays, solenoids, switches, electric motors.
Something near the antenna lead-in or corrosion at lead-in connections.

Solutions:
Always verify grounding first: if more than one component interferes, a poor ground probably exists.
Pinpoint the source: suppress, shield or replace.
Reroute noisy wires if necessary.

Sideways
Sideways noise is any noise which gets quieter when slowly removing the radio from the instrument panel. This noise enters the radio throught the radio case.

Causes:
Noisy wiring or hoses behind or on top of the radio or antenna lead-in
Radio or antenna lead-in

Solutions:
Suppress or shield the noisy wire or hose, or re-route it. Shield the radio.

Backway
Backway noise is any noise that enters through the radio wiring harness. This noise can be heard at minimum volume.

Causes:
Poor grounding of: the radio, an unsuppressed electrical component, poorly routed wires or defective suppression of an electrical component.

Solutions:
Suppression can be installed at the source (preferable), the radio or both.
Pops are best suppressed using capacitors. Squeals and buzzes are best suppressed using filters.

Harness Related Noises
Causes:
Pinched wires, broken or shorted audio wires, defective connectors or speakers or a screw through a wire harness.

Solutions:
Localize problem to one side, front or back or speaker location.
Verify speaker/amplifier operation using spare speaker/amplifier.
Use channel swap harness (1226788) to check wiring.
Track wiring for defects, brakes or shorts.

Note: Harness related noises have a tendency to be intermittent.