Battery Drain within an hour

[whitenemesis]

Left side towards the rear of the engine block (viewed as sat in driver's seat)

Large flatish square box, thin control wire, big fat power cable. Disconnect the power cable and insulate

 

[Ted]

If it is that (seems highly likely) be careful if you remove it while the battery is connected as

It will be hot
The cable leading to it will be live and capable of passing a lot of current.

 

[whitenemesis]

Supply is directly from the alternator, so with engine off shouldn't be any current. Good practise is always to treat as live though

If it has malfunctioned it won't be hot as it's usually the element that has burnt out

ETA - Of course as it's malfunctioned the control will be stuffed, hence the battery drain.. proceed with caution..

 

[Jake89]

Can i get to it from the top of the bay (without removing loads of stuff) or is it better to jack it up and go from underneath?

Ive had a look and i cant even see it. Ive searched and it says its under the Inlet manifold.

 

[whitenemesis]

WIS states to remove the starter motor to access the unit, not sure if one needs to if just disconnecting the cable.

 

[Jake89]

Its gone to a garage now. I couldn't get to it without taking the starter motor out and all my axle stands are currently in use on my track car. Fingers crossed.

 

[Jake89]

UPDATE - Just spoken to the garage and they have disconnected the 12v wire to the coolant pre heater (disconnecting the connector made no difference).

They said it's dropped from 26amp draw to a 12amp draw though...

 

[mersum1es]

Do you have breather hose heater installed? If yes, could be worth to check/disconnect it next... 12A is still pretty much...

 

[richard]

Should be a few milli amps once its gone to sleep

R

 

[Ted]

Is it possible there are two of them?
Certainly sounds like the controller (what/wherever that is) at fault.

 

[Ted]

Just had a thought.
You sure it is 12A and not 12mA?

 

[Dec]

It should be cooked by now.

Dec

 

[holbay]

Does this car have the 1000 Watt electric heating element built into the cabin heating plant my 2003 E320 Cdi has this and it is known for the controller to go faulty on them and drain a battery damn fast when it comes on with car shut down. I have been told it has a 250 Amp fuse located under the carpet under where your left foot would sit and most people remove the fuse when the controller goes faulty..

 

[whitenemesis]

The 203 does not have the peltier heater as fitted to the 211 CDI models

 

[Auto-mobile]

Had one of these a couple of weeks back, 18amp draw, remove starter to gain access and disconnect the main feed to heater booster to isolate the cause of the drain, tape it up really well if you choose to not replace the unit ( coolant needs to be drained if you do)
After - drain showed as 4amp then 0.5 when can has shut down.

The heater booster is not fused nor is there an accessible live feed to disconnect.

Hope this helps someone for future reference.

 

[Westcoastauto]

Heater booster on side of the engine, above starter motor.
Disconnect it... Drain will disappear... Not too bad to change they are
About £400 ish...

 

[bigpg]

I had a boot catch cause a drain of 2 amps. It seems as though it was the relay that operates the PSE pump to close the boot; changed it and all in now OK.

 

[Isaac1400]

Hi All,

I have a similar problem and still cant get to the bottom of it.

After having is scanned and checked by electrician it pointed to the heating block. Had that disconnected but still failed to stat. Its very other day it fails to start.

Have so far:

Disconnected the heating block
Cleaned and greased the grounding points on the engine
Replaced with a better stronger battery.
Taken it to 3 different mechanics.

At that cost I was better off taking it to MB.

Any suggestions would be appreciated.

*Also is there any device I can use to get the car started myself as opposed to calling out AA every time. I have been advised not to jump start it as it can cause problems to the electrics.

Thanks