Sean1234

Over the weekend my battery went dead as my wife left a light on inside the car. I user her car to jump the E550 however once it was running again I get the "pre safety function limited" error when running the car. The cruise control, pre brake and other features no longer work. I checked the fuses and gave the car a wash as from reading other threads that error generally has to do with dirt on the sensors not a issue with them.
Any one have any idea on what this could be? The only thing I could think of would be something happened when I jumped the car. But if that was the case I would get a different error msg.

noka

Was the battery fully charged after jump starting?

Sean1234

Ya, I let the car run for 10 minutes. Then yesterday I did about 3 hours of driving so it should be fully charged by know. I did see in the book not enough voltage could be a cause for this but figured after all that driving I would be good.
It is the original battery and is 5 years old know. Could it be that after going dead I just can't get the same level of charge back in it?

noka

When a battery is so badly discharged, I doubt just driving it would put enough of a charge back on it and even if it could, I doubt that 3-hr would be anywhere near sufficient. I would have it charged (with appropriate charger) and then tested.

Sean1234

Do you think by driving it will get the charge back in? Or should I look at buying a battery charger or at least look at getting the battery tested?

Sean1234

I'm going to grab a charger on my way home tonight. Do I need to connect the charger directly to the battery in the trunk? Or can I just use the terminals under the hood?

noka

Don't use a cheap charger. Incorrect charging of a battery could do more harm than good. Check your owner's manual (and/or this forum) for correct charging procedures. I would have the battery and charging system checked by a competent tech.

Mud

I thought that these cars, like many today, have an auto shut-off for any lighting left on to avoid battery drain? I've noticed that if I'm doing something that involves trunk or doors open the lighting will shut off on its own after a few minutes.
Also, I doubt a 5 yr old battery is worth messing with after such a complete drain, seems these days 3-5 years is average battery life. I'd rather just change it out rather than mess with it and eventually wind up getting stuck somewhere.
An easy way to check charging is to check voltage at the battery terminals while the engine is running - should be about 14 to 14.5v.

Sean1234

Went home last night and got a battery charger, put it on and the battery was low at 25 percent. Took about an hour till the unit said it was fully charged but the sensors still have not come back on.

Agreed I think the battery might just be toast. Going to take it in and have it tested to see what the story is.

Anyone have a suggestion for a good battery to use? Or am I best just getting the OEM one?

Mud

Most batteries are mfg by a only a couple of companies so you're essentially buying by branding.
Be sure to match the battery size and amperage ratings. Going over on the CCA's and rated amperage has never been an issue, it just means more capacity in the battery. By that I mean if the OEM battery was rated at 700 CCA, you can buy one rated at 750 CCA's as an example.

Be warned almost all batteries have increased in price over the last few years, so shop around. I buy based on capacity/warranty/price.

I just bought a new battery for the truck from Walmart, last one for a previous car was from Advance Auto, as mentioned I shop around. Your dealer may be competitive but IMO that may be doubtful lol.

thefisch

most will say warranty on MB OEM battery is not worth the cost when you get a longer warranty for less from most battery stores. Not sure if AGM is required, but the OEM is AGM in mine and it can run $150-$200 for a replacement.

Sean1234

Does anyone know if the pre safety stuff runs off the main battery or the aux one?

Arrie

I buy my batteries from AutoZone. Have never been disappointed with them.


If you choose to go there ask them to read the codes from your car. If the sensors are not working there should be a code for it. Perhaps there is one saying "Low voltage" and ends the guessing game. They read the codes free but are not allowed to reset any by the law.

BeachBunny

Depends on the year of the car & how it's equipped. In general: 2014 and newer, pre-safety and cabin run off the aux battery once the aux battery has a sufficient charge, then seems to run off the aux battery until the car is shut off. 2013 and older, pre-safe runs off the main (engine compartment) battery.

dbldpr

Did you check to see if your car had more than one battery. From what I have been told you can have as many as 3 batteries in the car. I may be wrong but I think you should check

Sean1234

Mine is a 2010 so that would mean its coming off the main. I did charge the main using a good charger connected to the connection points under the hood and that did not solve the issue. This weekend I will hook it up to the aux one under the too see what condition its in.

When you say main under the hood do you mean trunk. It was my understand the main is in the trunk and the aux is the one under the hood?

Sean1234

Ya it has two, i have charger the main and this weekend will hook it up to the aux one to see the condition and look at charging it as well.

konigstiger

MY10 e550 has one battery in trunk, and backup battery for transmission electronic gear selector under dash; 4matic one in engine compartment + backup under dash. If you think/know your vehicle has different PM your VIN I will confirm. MY advice, have an independent check the battery and retrieve/clear any fault codes that may be stored with MB DAS. As a matter of reference attached relevant OM pages for membership.

Sean1234

I can only find one battery under the hood on the left rear side if you are looking at the engine. It is a big one so this has to be the main. I can not find a aux one and after doing a bunch of reading online it looks like CAN/US models didn't get two batteries.

Sean1234

Okay so to end this in a bit of a funny way. I was driving to curling tonight, yes curling we do that here in The Great White North, i.e. toronto ...

I was playing with the in dash setting and decided to do a factory re-set just for the sake of trying it. Well wouldn't you know it but that seems to have solved the problem. No more warning messages and all pre-safety functions are back up and running.

I'm still going to have the battery looked at over the weekend just to be safe but knock on wood everything is back up and running.

Thanks for all the advice too all!

BeachBunny

I believe that the MY10 still has an aux battery underneath the driver's side dash. IIRC it only powers the transmission selector though, nothing else.

RobertBuduen

Our Mercedes Benz B-CL-Class have a serious problem since July 2014, When I star the car them 20 min in the middle screen show me as follows: PRE-SAFE functions Limited See Operator's Manual, Inoperative See Operator's Manual, Them the car is slow without power, risking my safety on the highway. I was at the dealer on 08/08/14 for first time and they not found the problem, after that time I have gone 2 times, its the same,. I can't resist this problem one again. What you can do for me? I am disappointed with this car. We appreciate your prompt response. Thank You.