Inspection Procedure 10: Noise is detected with engine running.: Diagnosis

CAUTION: Never connect a noise filter to the high tension cable (spark plug wire). Spark plug wires incorporate resistors which have the effect of suppressing noise. If a spark plug wire is found to be causing noise, it must be replaced.

CAUTION: Confirm that the noise is not from an external source.

CAUTION: Noise prevention should be performed by suppressing strong sources of noise first.

DIAGNOSIS CHART

Description of noise	Condition	Cause	Solution
AM, FM: ignition noise (popping, snapping, cracking, buzzing)	Increasing the engine speed causes the generator whine to speed up and the volume to decrease. Disappears when the ignition switch turned to "ACC", and engine is off.	Electrical interference from the spark plugs. Engine noise.	Check or replace the ground cable. Check or replace spark plug wires.
Other electrical components	-	Noise may intensify due to aging electrical components.	Repair or replace the electrical components.
Static electricity (cracking, crinkling)	Noise disappears when the vehicle is completely stopped.	Noise occurs when parts or wiring move and contact vehicle body.	Return parts or wiring to their proper position.
Static electricity (cracking, crinkling)	Various noises are produced depending on the body part of the vehicle.	This may be due to the recent removal of the front hood, bumpers, exhaust pipe and muffler, suspension, etc.	Properly ground parts. Properly ground all body parts.

Fig 1: Locating Ground Cable (3.0L Engine)

Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.

Fig 2: Locating Ground Cable (2.4L Engine)

Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.