pmkalby

So I have had an intermittent slow battery drain issue in my 2010 E-550. Sometimes car starts slow and I've suspected something is staying on.

I went into the garage today to look at something, and saw the display on showing "PRE SAFE functions limited see operator's manual"

My keys weren't on me. I didn't open or touch the car. It was just sitting there on.

I have to go for an oil change pretty soon, will have to see what dealer says, I have certified warranty on this new-ish to me used car but I hadn't seen any threads here about this issue with the car off-- just when driving, etc.

Oh, and I do not have lane assist or those options-- so I don't really have much of a Pre Safe system anyhow do I?

thefisch

That's strange. For background, how old is your battery? Has it ever been dead after sitting overnight?

Was the display showing 'presafe limited' when you eventually opened the door or had it gone away?

pmkalby

The battery did go dead overnight months back. Dealer replaced it as a courtesy since the car had just been certified and since I paid for additional CPO warranty. So the current battery is only a few months old.

For the past few months it does sometimes start hard after sitting a few days. Slow initial crank then fires right up. Was going to have them check at next scheduled service.

After i saw the display on I went and got my keys and started the car to see if it would be dead and I'm a bonehead and I don't remember if it went out when I opened the door or not.

pmkalby

Sometimes when the car is off I hear noise from
the airmatic system too. A pffft of air being released.

beejAMG

"pre-safe" warning normally goes on when your battery is about to go. it will start and run your car (for now until it totally dies) but with limited safety features. car will temporarily switch off the least necessary functions or safety features that uses electricity until the battery runs for a while and charges.

since you said dealer replaced it recently. you may have gotten a bad battery.

belarus27

Could be the alternator going bad if it takes it longer to start sometimes.... and not charging the battery properly

beejAMG

+1

or this...

thefisch

step one is to get the battery and charging system tested.

KEY08

listen to the good advice you just received. The Airmatic noises when parked and turned off are completely normal. These cars like to work all of the time.

Diesel #2

I am quite certain that this is one of the operations of the self leveling system.

pmkalby

Thanks. As mentioned, I will get the dealer on the issue when it goes in soon for maintenance.

I wonder if it could be the second battery that is backup for the transmission that's going south and that's triggering it. I believe this car has a second battery if I remember right what I've read here.

I'll get them to check everything out. They checked charging system when they put the new battery in because I was seeing low voltages while it was running but obviously checking again seems to be in order. I was watching via an OBD-II scanner that links to my phone.

pmkalby

Ok so update time.... since last post I found the transmission battery, it was just fine. Got in for service and they said nothing is wrong. Advisor said they reprogrammed the presafe but the work order just shows the tech drove it and scanned for codes, none found.

They said charging system tested fine. Left it parked 2 nights and it started strong... they tested the battery and it's good.

Of course I got it home Wednesday mid day, and Friday afternoon it started hard.

Tech noted I have several aftermarket electrical devices. Always makes me wonder if they just assume.... but I have checked myself by unplugging them all and I still got the drain after a few days.

After 3 days of not being driven it needs a jump. That's rare but it's happened 2 x


Anybody have any ideas?

pmkalby

Could my keys be too close to the car waking it up? Dealer said if it was that I'd have dead key batteries all the time.

pmkalby

Car was dead today and had to jump it....

I guess back to the dealer I go. CPO warranty will cover it but they have to find it first.

Abrown3mtg

Did they ever resolve this issue? I have the same problem with my car... (Pre safe limited before car starts, once started get a variety of warning lights such as abs, esp, abs, check engine, etc, no power steering, etc). For a few days it I could turn off the car, open the door, restart it and it was fine. Today that did not work. I ran codes a few days ago and nothing popped up.

No codes when I ran it with star, even while the problem was active. I had to drive to a meeting due to no time to check further and it made it the full 15 miles. I disconnected the battery and have let it sit a few hours. I'm going back to the shop after work and will try and troubleshoot it further.

Hoping you found the culprit. I did replace the battery not long ago and don't believe that is the issue but will have it tested again regardless.

pmkalby

I haven't seen the pre safe functions limited message since service noted above. Today I had to jump the car- it was Wednesday afternoon and I parked it Saturday night late - that's how long it took for it to drain enougn everything turned on but the starter couldn't crank the engine over.

Do you have the message only, or the battery drain, too?

Abrown3mtg

As of now just the messages. Voltage has been good. Battery was fresh about 6 months ago. I believe there is a short or corrosion somewhere in the CAN network or a wiring harness that is linked to one of these systems.... I spent a couple hours with a STAR computer and replicating the last standing notification of ESC inoperative see service manual upon start up. I finally got that one to clear up and drove home without it coming back. We will see what happens in the morning. I don't like "fixing" problems that I never discovered the cause of... It was happening last fall as well.

pmkalby

I caught the car, locked, unattended, keys 100 feet away- with the display on. I got video. Will get it back in for another look and have a chat with the manager I guess. Service advisor said they'd "go through the motions".

Well, maybe he's not aware of the meaning of that phrase....��

pmkalby

OK so I feel like an idiot, but in case anyone else ever has this issue and finds this thread, I feel like I need to explain what I found.

It was the Valentine 1 Savvy module. Savvy is a module that plugs into the car's OBD-II port and supplies data and power to the V1 detector. The old versions have a known compatability issue with Mercedes, and when I unplugged the detector, the Savvy was still in the OBD-II port and that kept waking up the car's computer so my test of accessories was flawed.

I got a new module from Valentine 1 and the new programming does not wake my car up. It's been fine for months now.

I assume the dealer didn't see the drain issue because they unplugged the Savvy to run their scans....

V1 tech support confirmed the issue, the Savvy old version programming didn't realize the car was stopped, and kept asking the computer how fast the car is going, even when the car was off. The car's computer was waking up every time it was asked for data, and that kills the battery pretty quickly.

Here's a link to V1's list of problems, and again, the new programming is fine, it's if you have an old Savvy module. Call V1 tech support for details, have your Savvy serial # and they can help. They offered me a free upgrade of the Savvy programming, but I was buying a new detector for my bike already and bought a package with new Savvy and solved issue that way (sold the old one to somebody who's car isn't on the list)

http://www.valentine1.com/savvy/savvy_problem_cars.asp