W203 Battery drain

142 TPL

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Ok I have a C270 CDI and a few weeks ago I had a flat battery in the morning. Got it started and drove to work. Over the next two weeks I check the battery drain and it's been 0.04 amps. Then today same again flat. Had about an hour to check it out and found a drain of 5 amps. Pulled a few fuses but as I was pushed for time drove to work and got our auto electrian to look at it. You guessed it back to 0.04 amps. All day starting it stopping it measuring it and no drain. With a drain that big I would think alternator or glow plug relay. Can a alternator be intermitant ? Any other thoughts ? By the way I have part electric seats and the constant live on the plugs don't go anywhere although the seats are heated
 

grumps

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devon
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190 2.5 16v m3 csl 230e 320cdi
Alarm siren, Block heater,stationary heater o/s/f inner wing under flitch, Outside temp sensor,front sam !!!
 
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142 TPL

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I know I know it could be anything and until it does it again I just got to wait, but what I would like to know is can the alternator play up intermitanly?
 

shorty

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I was working on a 203 a few weeks back with the same random battery drain as yours . When I checked I could find no drain , I think all that you can do is keep checking the car then when you discover the drain start pulling fuses , this should isolate the cause
 
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142 TPL

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Thanks Shorty
That's what I plan on doing. But it's so frustrating not knowing when it's going to happen and sods law says it will do it at the most inconvenient time
 

brens-e200

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Mar 22, 2009
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naas, ireland
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1990 230E W124, 1992 C124 220E
electric draw form motors on seat adjustment

hi

sorry but i seem to remember reading somewhere that if you have electric seat adjustment the constant 12v feed to the seats cause a drain on the battery if one of the motors develop a fault or there is a fault in the wiring inside the seat.

there is also a mod that you change the constant feed to the switched feed , if i can find it i will post again on the web.

A quick test is to get the seat right for you ( just in case you have the memory option fitted ) and disconnect the power cable under the seat ( should have 3 cables going into it ), remember do both the drivers and passengers side.


regards

brendan
 
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142 TPL

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Thanks but I have pulled the plugs on the seats and although the wires are there the constant live does not go anywhere as there is no pin inside the female side of the plug
 

brens-e200

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naas, ireland
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1990 230E W124, 1992 C124 220E
no probs, so when connected do you have electrical control of the back of the seat and the lower part as well ?

tia

brendan
 
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142 TPL

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Yes it is just manual back and forward the rest is electric and heated
 

Stan the Man

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Nov 8, 2005
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Plymouth
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W205 C250d Sport Premium + Auto
hi

sorry but i seem to remember reading somewhere that if you have electric seat adjustment the constant 12v feed to the seats cause a drain on the battery if one of the motors develop a fault or there is a fault in the wiring inside the seat.

there is also a mod that you change the constant feed to the switched feed , if i can find it i will post again on the web.

A quick test is to get the seat right for you ( just in case you have the memory option fitted ) and disconnect the power cable under the seat ( should have 3 cables going into it ), remember do both the drivers and passengers side.


regards

brendan
I think you will find this applies to memory seat controllers, not electric seat partial adjustment. Faulty memory seat controllers are a known cause of excessive battery drain.
 

Justin1600

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C43 AMG
On these models the battery drain is normally a seat control unit under the front seats ( full electric seats ) or the overhead control panel :thumb:
 
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142 TPL

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On these models the battery drain is normally a seat control unit under the front seats ( full electric seats ) or the overhead control panel :thumb:
What part of the OCP fails, is it that the whole thing needs replacing?
 

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