electrical "hum"

[iammiowngod 10+ year member]

My dad has a 99 BMW Z3 with an Eclipse deck. Theres also other audio components but I have isolated them out of the equation. After 30 seconds-20 minuets of driving you start to get a kind of alt. wine/distorting/electric hum that isn't volume dependent. I have ran my own set of wires from the HU to the front kick panel speakers. I have also ran my own ground(to the chassis), power(direct to the batt.) and 12 volt switch from the ignition. I have completely isolated any and all stock wiring form the HU and still it picks this interference up. I also swapped out the HU for a completely different make and model to no avail. All I can say is its coming form the power system some ware and it's not picking it up by just being close to a main power cable. Any suggestions are welcome.

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[XtrmAudioCncpts 10+ year member]

Check the grounds with a dmm it could also be a bad interconnecter

 

[danteBirosel 5,000+ posts]

Check the grounds with a dmm it could also be a bad interconnecter

i'm also having the same problem.. i was wondering in the DMM what setting should i set it too and where do i place the red and black connectors on to test?

 

[iammiowngod 10+ year member]

I'm not using any interconnects with it. The HU is wired directly to the speakers. The ground should be good but I'll check it, some one also suggested running a ground back to the batt.

 

[XtrmAudioCncpts 10+ year member]

i'm also having the same problem.. i was wondering in the DMM what setting should i set it too and where do i place the red and black connectors on to test?

Red wire to the wire you are testing black to any good ground. Setting on the dmm before the head unit, direcect current volts, after the hu anything coming from the hu alternating current setting

 

[iammiowngod 10+ year member]

OK the ground was good but I have ran one back to the batt. so we will see what happens. I think its something in the charging sys. It only kicks in after the car is warmed up so it must be a faulty component that heats up and creates noise. Any more suggestions?

 

[azbass 5,000+ posts]

All bmw's that i have worked on, have a low hum.

 

[iammiowngod 10+ year member]

My 328 didn't and neither dose my M3. His didn't always do this, it's been happening off and on for a year or so but now its constant.