W219 Whining noise when connecting battery

[GeneralNDK]

Just changed my dead battery after the car has been sat for 3 months, also I cannot start the engine yet as the intake is still off.

Now it has developed a continuous whining from the front passenger side wing , sounds like a motor stuck on.

Anyone have any ideas what it could be?

 

[Larkone]

Is it the alarm unit - they have their own battery which may have died/gone flat whilst the car has been sitting for 3 months.

 

[GeneralNDK]

Correct me if am wrong, the siren is just a loudspeaker?

I'm getting more of a electric motor stuck on noise, I will get a recording of it when I get home today.

 

[MrGreedy]

I get a noise like this when I connect my battery up, but it's only for a second or two.
I hear it on my wife's Golf as well.
I'd guess at something like a vacuum line pump or fluid pump. Is the central locking on a vacuum line? Have you had any issues with locking?

 

[GeneralNDK]

No Issues with locking or unlocking, as long as i have the battery connected it works as intended.
But it does sound like a fluid pump.

 

[GeneralNDK]

Managed to get some work done on the car today, started the engine finally.

Unfortunately noise is still there, managed to get a short clip of it.

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Any suggestions welcome, I'll get the wheel off tomorrow and try to disconnect whatever is asking that noise.

 

[MrGreedy]

Wow, that's a lot louder than the 1 or 2 second pump/motor noise when I connect the battery. I can barely hear the noise I was talking about, so it's not the same thing.

That sounds like a buzzer or alarm it's so loud (if not a faulty one). Try pulling a few fuses, one at a time, replacing as you go. Car turned off, then back on to check. As in, don't pull fuses with it powered up. If it is making this noise even with the car off, disconnect the battery between fuse tries. Start off with obvious and non-essential fuses, and if it's in the passenger wheel area, fuses for components in that area.

For starters, the alarm fuse. Windscreen washer system, headlights, ABS pump or similar.

 

[MrGreedy]

People often disconnect the alarm siren/fuse on older Mercs due to alarm siren fault. This is my first thought.

Does your horn also work as it should?

 

[GeneralNDK]

I have tried the horn and it works as it should,
Any ideea what fuse it is for the siren?

 

[grober]

HAVE YOU GOT AIR SUSPENSION-IIRC THE COMPRESSOR LIVES AROUND THERE?

 

[GeneralNDK]

I do have airmatic and I suspecting the compressor, but my suspension has not had any issues previously. I'll try and unplug that to see if it makes a difference.

I'll update you guys tomorrow to see what I end up removing/disconnecting.

 

[grober]

COMPRESSOR AND CABLE SPECIFICATION MERCEDES CLS-KLASSE [Car] [CHASSIS] (EUROPA)

COMPRESSOR AND CABLE SPECIFICATION MERCEDES CLS-KLASSE [Car] [CHASSIS] (EUROPA)

mercedes.7zap.com

 

[GeneralNDK]

Managed to get round to checking out this issue, turns out it was the headlight washer motor that was stuck on, disconnected it for now

Only one SRS issue left to fight now...


Thanks to everyone