hadam

I got minor problem with my Sony Ericsson HCA-20 phone kit.

I drive 1997 E-420 W210.

The person on the receiving end of my phone calls from my car hears the whining noise.

First I had phone kit power from 12VDC of cigarette lighter. The whining noise was high due to the grounding loop problem from lighter.

So I went and change the 12 VDC power source from cigarette lighter to tap into the Radio head unit. So now my Sony Ericsson HCA-20 phone kit is getting 12 VDC power from same source as Radio Head unit.

Now the whining sound is very minimal, but still some whining is there when I am driving around 10-40 mph.

So my call receivers now don't hear whining sound when I am driving around less then 10 mph or over 45 mph.

But they still hear very little whining sound between 10-40 mph.

Once I reach over 45 mph the sound goes away.

Please note that I don’t hear any of this whining sound on my phone car speakers, it only on the other end when some one is receiving my calls.

I need advise on grounding. I know it is grounding loop problem.

Where should I connect to car frame or car battery the Negative (-) 12VDC, so my caller don't hear very little whining noise.

Any help will be appreciated.

Parrot of Doom

Its the alternator.

Connect directly to the battery negative terminal. Also, I suggest you do not use power from the back of the radio - best to get it directly from the battery terminal (although this may drain your battery over extended periods, so perhaps you could find a switched live from your ignition).

While you're there, clean the negative terminal, and the connector, then reconnect and coat with vaseline/grease. Its also worth cleaning other earth points on the car, I don't know where they all are but on mine theres one at the front of the passenger footwell behind the carpet.

Check in the engine bay for any earthing points, and make sure they're clean and protected from water.

zstig

I make calls when my kids aren't in the car to keep the whining noise to a minimum.

benzmodz

Battery ??? Geez. Just use one of the fuse boxes in the car. Where do you suppose they eminate from.

Parrot of Doom

The point is to reduce the amount of noise travelling through the car kit by connecting to as clean a power supply as is possible - connecting to another earth away from the battery may induce an earth loop.

Its about 30 minutes work to run the cables to the battery, just under the sills and along the back seat.