Question about 2003 Mercedes-Benz E-Class

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My 03 E500 is having a problem where the battery keeps draining if I let it set turned off for over a 24 hour period of time. The altenator is good and so is the battery. There is a 300 milliamp drain somewhere when it is shut off. What do you think is happening?

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Posted on Jan 02, 2017

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SOURCE: battery draining

crank your car leave it running and pull the hot cable off the battery tell me what happens

Posted on Nov 20, 2008


SOURCE: When truck door is opened the courtesy lights are

what is happening after you close the doors and lock it.. you may have a parasitic drain coming from a computer if everthing doesnt shut off or you just may have a bad battery or alternator. A bad diode in an alternator can drain a battery even when car is not in use

Posted on Nov 01, 2009

  • 35 Answers

SOURCE: my car mb c220cdi 03 reg draining battery in two

sounds like a battery draw you can test it by hooking up an amp meter to the battery (you get a high reading if there is a draw) then you start pulling fuses ONE BY ONE and WATCH THE METER when the draw goes down you know there is a promblem with the curcuit you removed the fuse from. Of course you want to have vehicle off,key out,and let the car sit for ten minutes before you test. also make sure you dont have anything plugged in to an auxillary outlet becuase they can cause a draw on the battery.NOTE: a 0.5amp draw will usually cause battery down in about two to three days depending on how long it sits.

Posted on Mar 24, 2010

  • 2841 Answers

SOURCE: Battery drain overnight

Can be a relay stuck. Make sure all the P/W will go up and down as they should. A relay can be stuck in the up position. The window switch can also be stuck. Check the Power Seat to see if a relay is stuck or the switch is defective. Move the seat back and forth, up and down, and recline. If a relay is stuck it will move on it's own. Are you sure the radio is not on all the time? Have you checked all the lights? Under hood, trunk, glove box, courtesy, etc?

Posted on Jul 16, 2010

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1 Answer

Battery being drained over night

Check to be sure that your hood light is turning off when you close the hood. Seriously. (Common problem.)
Remove the bulb from the hood light to see if the problem persists. If the battery no longer drains, replace the hood light assembly.
Also, run the car for a short while, then turn the car off. Leave the car off for an hour, then feel the back of the alternator. If it is hot, the diodes are bad in the alternator.

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Did the shop actually connect a scan tool and check the diagnostic code to see if it is at all related to the charging system? A bad alternator or battery could certainly cause the "battery" light to come on, but it's less likely to cause a check engine light. It is possible though, especially if the battery voltage is low and the alternator is not working to keep the charging system at the correct voltage once the engine is running.

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Your battery has a few dead cells, replace the battery. A good battery should crank your engine for a while before it goes dead.

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Check your battery cable connections on battery and on starter and ground to make sure they are very clean as well as tight.

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You either have a short or a power drain. You may have a defective mercury switch in the trunk which is leaving the light on. This would drain the battery in a few hours. Also check the switch under the hood. The easy way to check this is to unscrew the bulbs & see if that solves the problem. Good luck!

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What does "C-error" on my radio screen indicates?

hello I'm an M.B. tech.-unfortunatly after you enter the wrong code (I beleive more than 3 times) it goes into a special security mode. The only way to unlock this feature is to keep power to the unit for 24 hours. If i remember correctly there are 2 different modes. The 1st mode is a 1 hour mode, the 2nd is a 24 hour mode. Your best bet is to take it to a dealer and have them reset it for you. If the unit is still in the first mode you can hook up a battery charger and keep the key on for 1 hour ( you could also do this for 24 hours). These vehiclles have an elctric throttle motor called an E.A. actuater. These units are very problematic and are usually damaged from somebody leaving the key on for an extended period of time. If you are going to attempt to perform this reset procedure yourself I would strongly recomend unplugging the actuaster when leaving the key on. The next problem would be if it lost it's synchroniztion you would need a scan tool to resynch. it. I just wanted you to be aware of this problem so you can be prepared. If you do try to leave the key on for 1 hour you probably would be o.k. it's the 24 hours that I'm concerned with. Make sure you turn the radio on when the key is on and hook up a battery charger. Be absolutly sure you have the right code because alot of people replace these units and don't replace there old code card. Good luck

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1 Answer

1997 catera

well Marie the reason your vehicle is acting this way is because even though you put new battery in you still have to have a viable altenator to run the vehicle. the battery is only used to start the vehicle and run the radio and lights and other accessories. while the vehicle is running the altenator is not only suppose to charge the battery but it is suppose to supply the amprage to energize and coolapse the coil to give the vehicle spark. a bad altenator while driving doesn't charge the battery it drains it . a quick check is to have the vehicle running and then remove the positive battery cable if it dies you know it's the altenator.... please rate this and good luck keep me posted

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