Urgently Need help with battery drain!

[dozypillock]

1.5 amps is far too high in standby, and will kill your battery in about 3 days. Something like a boot light bulb will probably draw about that. Have you checked the obvious?

Neil

 

[dasachmo]

1.5 amps is far too high in standby, and will kill your battery in about 3 days. Something like a boot light bulb will probably draw about that. Have you checked the obvious?

Neil

Yup. Opened the boot and the bulbs not warm.
If I pull out the bulb will it break the circuit and stop the drain. I could go and take it out and don't mind no light there.

What is the normal draw from the battery?

Is there any other way of diagnosing this.
I read that you connect the battery in series and then pull fuses out until it drops which will identify the culprit

If the car was connected to star... Would it show what wad draining it?

 

[gbjeppm]

Normal draw should be about 50ma or under.

You also need to wait for the car to shut right down, which can take up to 20 mins.

Everytime you open a door you will wake the car up.

In my experience STAR will not pinpoint the culprit on cars of this era. It certainly did not on my 203.

 

[grober]

Have you tried disconnecting the alternator [ engine off] while monitoring the current drain?

If its not the alternator and the alarm is not sounding there could be a problem with the alarm unit they do go faulty see this thread for location http://www.mbclub.co.uk/forums/electronics/168939-alarm-issues-w203.html

 

[dozypillock]

Yup. Opened the boot and the bulbs not warm.
If I pull out the bulb will it break the circuit and stop the drain. I could go and take it out and don't mind no light there.

What is the normal draw from the battery?

Is there any other way of diagnosing this.
I read that you connect the battery in series and then pull fuses out until it drops which will identify the culprit

If the car was connected to star... Would it show what wad draining it?

Looking further up, you should always put the meter in series with the negative. Less chance of the battery earthing, and causing you major problems.
Only way to trace draw yourself is to connect meter up, with doors shut etc, so no lights on. Key out, and just work your way through likely fuses, plugs etc. As somebody suggested, even disconnecting the alternator may drop the current.
Something is drawing too much. It is free to try this method yourself. Even commands have been known to go wrong and draw excess current.

Good luck. That, or take it to somewhere and get them to fault find it. 100m/a is probably about the most you would want as a constant draw.

Neil

 

[gbjeppm]

You need to get a baseline draw, connect up the Multi Meter in series, shut all the doors, and come back in half an hour.

And see what the reading is when car is asleep.

You will also find when you pull fuses and replace, that the draw may go up temporarily as the car may wake up.

Patience, and knowing the baseline draw is key.

When I did it on mine, it took me 6 hours in total, going backwards and forwards.

Have you tested that the alarm siren actually works yet? My money is still on fuse 8.

 

[dasachmo]

Okay guys.
Gonna have a read about the alarm.
I armed it. Opened with the emergency key.
The hazards flash but no siren goes off.

Locked the car window open and waited for a while. Stuck my arm in and same thing... Alarm flashing and no siren.

Is this a dealer only thing or can I disable and fit a aftermarket alarm.

 

[gbjeppm]

So you have no siren, exactly the same issue as mine.

Get the baseline as I said above.

Then pull fuse 8 in the boot., and wait for it to all shut down again. Hopefully you have found the problem.

You can then either replace the siren, or just remove it, and put fuse 8 back in,

 

[Dec]

As you have intentionally triggered the alarm, the siren should have sounded, it didn’t, so its faulty.
Unplug the siren as soon as you can, removing fuse 8 may not completely disable the alarm… the only sure way is to unplug it or remove it from the car.

Dec

 

[gbjeppm]

As you have intentionally triggered the alarm, the siren should have sounded, it didn’t , so its faulty.
Unplug the siren as soon as you can, removing fuse 8 may not completely disable the alarm… the only sure way is to unplug it or remove it from the car.

Dec

Agreed as i said replace or disconnect the siren is long term fix.

But to prove it is the culprit pulling the fuse will work and you should see a drop in draw.

Fuse 8 also powers the radio antenna, so you would lose that, therefore not a long term fix.

Siren is under the passenger front wing, behind the arch liner. You will need a security torx bit to remove it.

 

[Dec]

before you start pulling the car apart, look for the simple things.

Make sure all interior lights are off, including the boot light.

Check that your alarm siren is working by leaving a window open, locking the car, then after a minute stick your hand in the open window and wave your arm about. The alarm should sound. Faulty alarms are common on the W203.

Unplug anything that is plugged into the cigarette lighter sockets.

Taking a week to drain suggests that it is a smallish drain. So maybe an ancillary being left on.

I would reconnect your seat modules first.

Bruce got it right above. If this Mercedes siren is 10 years old then it’s nearly guaranteed that the siren is at faulty, particularly since its not sounding when triggered. Good guide below.

Dec
[YOUTUBE HD]BzmpeK1TFfw[/YOUTUBE HD]

 

[dasachmo]

Thank you so much Dec!!! that's an amazing guide

I was a little worried coz reading through posts people had difficulty in finding the siren but this guide is perfect and it seems relatively straightforward to repair.

Just two quick questions about this:

in the video, he removes the front right side wheel as the siren is behind the mudguard on the battery side. My C320 sport (05 plate the facelift one I believe) ... the battery sits on the opposite - left side. Do I basically do the opposite?

Also, does the siren have to be a dealer part ? i don't need anything reconfigured on my key / the IR , at all do I ?

i hate to think what merc will charge - my local one is Loughton... i'll call them tomorrow but from the video and the value of my car... its probably going to be ridiculous!

Found the part as : http://www.carparts4less.co.uk/cp4l...af5b2585ff732b536b13d1da9d5fe28dcd9b72&000716 i think

 

[dasachmo]

PS. if this works. I'd really like to say thank you to everyone above for their comments and help. I really do appreciate how prompt and quick and extensive your replies have been.
If it doesn't, I'd still like to say thanks!!! everyones been really knowledgable here... and has a common sense approach. Thank you guys

 

[gbjeppm]

I hope that is your problem.

In the video it is a left hand drive car. On a right hand drive car, the battery and siren are on the passenger side.

You can get a new siren from the dealer, or from ebay/other sources.

Here is an example.

Genuine Mercedes-Benz Alarm Siren A-Class 169, C-Class 203, E-Class 211 NEW | eBay

When you remove the old one, have a look at the part number, and google it.

Or ask MB for a price, you may be pleasantly surprised.

Nothing else needed, no key coding etc, its a straight swap.

Good luck

 

[gbjeppm]

The part you posted from car parts is the horn by the way.

You need the alarm siren.

 

[dasachmo]

ahh yes, it would help to get the right part!
I'll call the dealer but would def want a new part... or a generic version if bosch or similar manufacturer do it. Time to do some searching!

 

[gbjeppm]

If you are happy to post your VIN, i or someone else can get you the exact part number required.

Then you wont need to remove the wheel and arch liner twice, once to remove, and once to put new part back.

Would still though suggest you get base line draw figures, as it may not be your only issue. It probably is, but better to be sure.

You will probably also need a set of these to remove it, I know I had to buy a set.

They are Torx security bits, they have a hole in the middle, to fit correctly.

 

[dasachmo]

aaah
the guy on the video simply undid it with a wrench. I'll have a look if I can get the bits.

As for the issue, will check with fuse 8 removal again and let the system 'calm down' / 'settle' and retest it.

no point in replacing it for no reason... that being said... if I simply disconnected it, should the drain stop because the circuit has been broken? or will it keep draining because of the error?

Any suggestions for the cheapest place for a replacement.

 

[gbjeppm]

If it is the problem, just pulling the plug out of the siren, will stop the drain.

Of course siren does not work, that did not worry me on a 2001 C320, as it was worth peanuts.

Yours may just be a wrench, as its a facelift, don't know for sure without looking at it.

If you do need them, Toolstation do a set for about 5 quid.

 

[Dec]

aaah
the guy on the video simply undid it with a wrench. I'll have a look if I can get the bits.

As for the issue, will check with fuse 8 removal again and let the system 'calm down' / 'settle' and retest it.

no point in replacing it for no reason... that being said... if I simply disconnected it, should the drain stop because the circuit has been broken? or will it keep draining because of the error?

Any suggestions for the cheapest place for a replacement.

Do not buy a used siren, only buy new, preferably from an MB dealer.
You don’t need to replace the siren, many do without an alarm, however, you will have no theft cover on your insurance.

Dec