alpine head unit howl/whine? NOT alternator or engine speed related - suggestions?

[jfc68]

I have an alpine CDA-9886 head unit in my 2003 silverado

have strange warble/howl/whine on AM reception only even when engine off....

tried new antenna connections etc and some ground investigations - no solution found yet

it is worse when battery is very cold - but tried complete separate battery power - same noise

sound changes slightly when brakes are applied or if power windows are used or if rear defrost is turned off and on - (when loads are applied the pitch of the howl / whine changes) the sound sort

of goes from low to high to low again - almost like some sort of feedback...

any ideas?

1) keep checking grounds etc incl. main engine/battery frame etc.

2) replace antenna or shield cables better?

3) have amp under rear seat but sound is there even when this is disabled by fuse removal

4) new ground for head unit / amp / antenna?

thanks in advance

john

Click to read more...

 

[ItsAJeepThing 10+ year member]

Find all new grounds. Sand down the location and try and find a good frame ground. Try some nice RCA's. Dont go spending a massive amount but the knukonceptzs ones are pretty nice for the money. You can try grounding your RCA's on your deck there is write up on how to do that on here somewhere.