W220 battery drain - help

[Mr Dosanjh]

Hi, I am new to the world of post 1995 Mercedes as have always run older 107's and 126's

Anyway here goes I have recently bought a W220 S280 this car has developed a drain on the battery which goes flat after about 6 days or so, even though the car is used everyday.

Does anyone have any idea what could be cuasing this, I have checked the battery with the car running and its over 14 v so the alternator is charging and its a brand new battery.

Any help would be welcomed.

Thanks

 

[Dieselman]

Does this car have Comand fitted, they can cause battery drain if they don't shut down.

Try pulling fuses while measuring the current draw, see which one stops the flow.

 

[ianjay]

I had a BMW 530 TdI with the exact same problem, and after changing 6 different computer modules (Not cheap!) It ended up as a worn grommet behind the dash
causing a short to earth.
New loom and grommet £48, Fitting £374!
I chose to plug the charger in evry night untill I could get some more overtime.
Hopefully this is not your problem, but checking the grommets won't do any harm.

 

[Mr Dosanjh]

Hi, No command fitted, but will try the fuses. Thanks

 

[nick mercedes]

Hi, I am new to the world of post 1995 Mercedes as have always run older 107's and 126's

Anyway here goes I have recently bought a W220 S280 this car has developed a drain on the battery which goes flat after about 6 days or so, even though the car is used everyday.

Does anyone have any idea what could be cuasing this, I have checked the battery with the car running and its over 14 v so the alternator is charging and its a brand new battery.

Any help would be welcomed.

Thanks

It's normally the door modules, a good man with a star can read the values for the various modules and see where the problem lies.

(nb all W220s do it from time to time)

 

[Mr Dosanjh]

It's normally the door modules, a good man with a star can read the values for the various modules and see where the problem lies.

(nb all W220s do it from time to time)

Hi, Thanks its the time to time thing thats harder to live with, as it always breaks down when I ve got to get somewhere!

I think it's time for an auto electrician, will keep you posted

 

[BlackC55]

The drains on 220's are somtimes very time consuming to find. You need less than 0.06A drain when the car is locked after 20-30 mins.

 

[Mr Dosanjh]

Right I am getting a drain of 1.54 after 30 mins, have pulled all fuses from all 3 fuse boxes with no reduction, any ideas anyone?

 

[Dieselman]

Alternator or starter are possibilities.

 

[BlackC55]

Was the car locked?

 

[Mr Dosanjh]

Yes car was locked, I have also been advised that there are some modules in the boot that can cause this drain, does anyone know where they located. also any other modules or fuses that I could try. help please. Thanks in advance to anyone who can

 

[BlackC55]

When you pull the fuses you may have to re-lock the car afterwards again and wait until it goes to sleep. This is why it can take ages to test fully. Were all the boot lights off too? Was the boot locked too? Were all the doors shut?

 

[AdamG]

"Right I am getting a drain of 1.54 after 30 mins, have pulled all fuses from all 3 fuse boxes with no reduction, any ideas anyone?"

Not sure if the all w220's are the same but my 03 w220 has 4 fuse boxes:-

2 in the engine bay, 1 under the rear seat and 1 on the left hand side of the dash board.

Adam

 

[Mr Dosanjh]

Yes I am begining to think alternator, not sure about starter

 

[tlzeebub]

Dont wish to hijack thread but I've just had to buy an alternator today for my W220 320cdi and theyre a bit spiteful, got all day tomorrow to try and fit it, looks like a pig of a job.

 

[BlackC55]

Dont forget to get a new water seal where the alternator mounts to the block. You will also need some coolant.

 

[tlzeebub]

Gutted, with a raging hangover I got the old one out in 1hr15mins Im thinking this'll be done by lunchtime the new one looks exactly the same only to find that the regulator plug wont fit, upon closer inspection the old regulator has part number 0124625019 and the new one ends in 014 could probably take the plug apart and make it fit but think I might damage something so thats it for today, bugger.

 

[Mr Dosanjh]

Hi, was the alt causing a drain on the battery with your car? if so how did you diagnose this? Thanks

 

[tlzeebub]

No I was coming home from work and the car just started to shut itself down and I had battery warning on the dash so I put another battery on and it did the same thing so I'm assuming that the alternator is dead

 

[Mr Dosanjh]

How much was did the alt cost? was it 2nd hand or new, mine is petrol so not sure if its water cooled or standard set up