How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Pete Your Own Question
Pete, Car Enthusiast
Category: UK Car
Satisfied Customers: 27537
Experience:  Over 17 years experience diagnosing and repairing automobiles.
Type Your UK Car Question Here...
Pete is online now
A new question is answered every 9 seconds

I have current loss on my Mercedes 270cdi 2003. even in

Customer Question

I have current loss on my Mercedes 270cdi 2003. even in summertime i have to recharge the battery. Have 2 new batteries and the generator/ alternator are 1 year. current drop is 0.3amp
JA: Have you checked all the fuses? Do you have a wiring diagram?
Customer: Yes i printed out a wiring diagram and tried to check all the fuses. could not find any bad fuses.
JA: What is the model/year of your Mercedes?
Customer: Model is Mercedes 270cdi 2003
JA: What year is your Mercedes?
Customer: from 2003
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: I had the car checked by a local Mercedes dealer. They could not find any specific current drop. I have also been on the net trying to find some hint. Have checked fuse by fuse to look for possible current drop but no luck so fare. I had BCM checked by the same dealer.
JA: Anything else you think the mechanic should know?
Customer: Only thing i have not checked is the auxilary battery relay.
Submitted: 10 months ago.
Category: UK Car
Customer: replied 10 months ago.
the battery are discharging with everything shut down and the car locked.
Customer: replied 10 months ago.
I have tried with a diagnostic tool. And started up the car. A picture of the battery comes up with a message visit workshop. This is during the test of BCM battery control module. fault codes 9055/9051 and 9050. The terminal 61 on the can bus is missing or faulty. 940 terminal 30 undervoltage. I also had a message about terminal 82 but forgot to write it down.
Customer: replied 10 months ago.
i have not heard anything yet about the above request
Expert:  Pete replied 10 months ago.

My name is ***** ***** I am a professional here at Just Answer. I noticed that your question had not received a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.

Try this battery drain test procedure below unless this was already done.If nothing is found or if this was already done let me know.

What needs done is to leave the key out of the vehicle with the windows rolled up and make sure everything is off with access to the battery.

Set the meter to amperage or milliamp and disconnect the negative cable from the battery.Put the leads in the multi meter the correct way (negative in negative and positive in the amperage or milliamp slot if equipped).

Connect one cable from the meter to the ground cable that was connected to the battery and the other lead to the ground terminal on the battery,this way the current is flowing through the multi meter.

After around 5 to 10 minutes see what the meter reads for a amperage draw.Normally you want to see less then 50 milliamp or less then .05 amp.

If you see over this amount of a battery draw/drain then your vehicle has an electrical component draining the battery.

From here you would remove one fuse at a time with the meter still in place and observe the reading on the meter until you come across one fuse that allows the draw to read below the 50 milliamp.This is the fuse or circuit that has the component on it that is drawing down the battery.Make sure when you remove one fuse if it is not the issue reinstall it and move to the next waiting a minute between each fuse removed to get an accurate reading.

Once you find the fuse or circuit its on then you would look on a wiring diagram to see what that fuse powers and unplug each of those components one at a time until you locate the component causing the draw then this component would need replaced.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service,your 5 star rating is appreciated.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete