Alpine 3402 Manuel D'installation Et D'utilisation page 23

PROBLEM POSSIBLE CAUSE & REMEDY
Adjustments have no effect on
the sound.
Verify that both front & rear sections of the
3402 are active & their EO IN/OUT switches are
in the IN position. EQ OUT indicator LEDs
should also be OFF.
Alternator whine through the
audio system with the engine
running.
Ground loops; connect grounds of all audio
components to the same point on the vehicle
chassis, verify that this point is a true ground by
checking for continuity with an ohmmeter
between the ground point & the battery's (—)
terminal, & follow the grounding
recommendations on pages 15 and 16.
The other audio components may need noise
suppressors on their battery or ignition
connections.
Check the vehicle's battery & voltage regulator.
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