Noise Diagnosis

STARTING DIAGNOSTICS
When diagnosing noise in the audio system, the vehicle should be outside with the hood down and away from power lines, transmission towers, tall buildings and any other distortion/noise producing area, such as near an arc welder. The first step in diagnosing noise in the audio system is to follow the radio noise diagnostic charts. However, if the charts do not yield a solution or if the chart referred you here, the problem is an obscure one.

SOURCES OF NOISE
In many cases, the noise is due to poor connections, an interference created by multiple causes, a poor ground to a module or motorized accessory or noise in a wiring harness.

Battery Connections
Make sure Battery terminals are clean and tight and that the Battery is fully charged.

Ignition Wires
Check for ignition secondary wires routed near any wiring harness that goes to the instrument panel. The high voltage in these wires will induce a noise into harness wires if routed too closely.

Spark Plugs
Also make sure that resistor type spark plugs are being used.

NOISE SNIFFER
One useful tool in locating this type of noise is a noise sniffer. Refer to Use and Construction Of A Handheld Noise Sniffer for proper construction of a noise sniffer and its use.