Mercedes Benz #

Hi Guys!

I have searched the forum but have been unable to find a thread that makes much sense to me.

We're getting this problem where the car displays an error message along the lines of 'Battery Protection: Convenience functions temporarily unavailable.' At this point the parking sensors switch of, the SBC brake features switch off and MOST annoyingly the climate control shuts down. After some time, the length varies every time, the functions come back online.

They have replaced the alternator regulator, believing that to be the cause, however the problem persisted. They have since replaced the system battery as well, again believing that to be faulty, however the problem has become even more frequent. The car is not under warranty and thus this method of guess and hope for the best is proving to be very expensive. We're not now willing to give the dealership free reign to replace whatever they want at our cost, because whether the regulator and battery were both faulty is now questionable. The problem appears to be elsewhere.

Has anyone else experience this problem and had it successfully diagnosed and cured? I would really appreciate any feedback/advice.

Thank you.

starbrite

First, you don't mention year and model....info helps. Also is this when the car is first started and then is normal after driving ?

Have they checked the BCU (battery control unit) ?
This controls how the battery(s) are charged and would result in the symptom you describe.

99bmw740il

mine does the same thing but only when my 2 diamond audio subs hit hard for a while

Mercedes Benz #

Thanks for the replies guys.

It's a 2003 W211 E320.

I think they have run a diagnosis on the battery control unit.

The problem happens at any time...at start up or when the car has been running for a while. When the climate control and command are switched off it still happens.

Clinton Horn

I have owned the same year / same model for about six months. I got the same code shortly after I bought it. I took it to the dealer under warranty.
They found a loose battery cable in the trunk. I know it was not the battery connection because I had checked it previously. It appeared that a new main battery had been installed prior to my purchase. I never found out exactly where the positive cable goes when it leaves the battery but it was arcing at the other end. They cleaned the corrosion and snugged it back tight. About 5 months and 4,000 miles and so far no further problems. Probably not a very common cause but it should be easy (and cheap) to check.

csumt76

Did they only replace the alternator's voltage regulator? I have encountered cars that would not charge properly with new voltage regulators. Basically, it would operate ok, but once you switched on a few consumers it wouldn't put out sufficient amperage and system voltage would drop below the normal operating range. I'd check the amperage ouput/voltage, then turn on the headlights/ ac blower/ rear window defroster and see what happens. The car should be able to maintain over 13.5volts easily.

Using the SDS you can monitor the amperage and system voltage within the battery control unit.

willscam

I have the same model car and had identical symtoms (plus headlights would flicker a little too). I told MB that I thought it was the alternator, they checked it out, agreed it was the alternator and replaced it under warranty.

dookhan

Also get them to check the secondary Battery (Front right) !!

b_rashed

sorry to bring up this old topic but im having the same issue. i just got the new alternator installed yesterday and the car was running perfect until today. the message came back on but before i got the new alternator installed i also got these two warnings- BRAKE MALFUNCTION and BATTERY/ALTERNATOR MALFUNCTION STOP VEHICLE. now im just getting the battery protection conv. message. any ideas. i just tightened up the battery cables in the trunk and going to see if that does it but if anyone knows any more information please let me know.

Benz-O-Rama

Are you still on your original battery? Might be time for a replacement. Sounds like it's having a hard time holding a charge.

Polar Bear

How old are the main and aux batteries? Does it go away after driving?

Roehl

you could have a short circuit somewhere that is draining your battery. I have read some threads that has this issue where as, there's module that has been running all day causing to drain the battery. It was fix thru SDS.

b_rashed

i got the main battery (trunk) about a year ago and paid around 150 for it so i kinda doubt that it is the battery, the front battery i have never changed but when i went to the dealer they said that both batteries are ok. now heres another thing i forgot to mention. i just got a 12in sub woofer installed with a 500 watt amp plugged in. however i made sure that they werent draining the battery when the car is off, so when i turn the key off the sub and amp both turn off. also i havent had the message come on again today, but then again i only drove for about 15 miles. i drive about 50-100 miles a day so ill see what it says tomorrow or monday and let you guys know.
oh and as for that module thing, im not sure if thats what it would be, i had one of my mechanics pull up the car on STAR and nothing came up.

Clinton Horn

I have followed these posts that deal with battery FSS warnings for some time. I believe that M-B was (is) overlyconcerned with electrical system defficiencies because of the electric brakes. It appears to me that the electrical system has to be in very good order to avoid these warnings (first time, loose cable: second time, faulty battery(s). In my case, both batteries were OEM and were approaching 75 months of age. The seat heaters coupled with short trips triggered the warning. I do not know that the smaller battery is the culprit in your case but I do have experience with identical Gmat batteries in motorcycles and I can say that they rarely last more than 4 years. It is probably more than coincidence that your problem has appeared in tandum with a change (amplifier) to the electrical loads. From what I have seen posted here, the warning usually clears itself after a short period of time. Since the car takes action on its own, it is diffricult to say that reducing load solves the problem. Perhaps the amp spikes enough load to put it over the limit . In any case, no one has had to walk home. I do not see any evidence of the warning causing anything more than annoyance, unless there is a real problem with the electrical system. FWIW I bought a correct (tube vented) main battery from Auto Zone for $100 with an 84 month warranty and a GMAT smaller battery from Batteries Plus for $69 and after one month, no more warning codes. We probably have put less than 250 miles on the car and my wife drives it daily. The point being that when everything is correct, with OEM equipment, the charging system will handle normal loads even with 3-4 mile trips.

kenikola

Is the new systems battery of the correct type and spec?
How did you install your sub and amp?

"Adding additional electric accessories:
When adding accessories always use a power supply that is fused through the
pre-fuse boxes. This will ensure that the BCM can monitor the current
consumption accurately.
DO NOT CONNECT ACCESSORIES DIRECTLY TO BATTERY TERMINALS"

kenikola

A problem with the aux battery triggers a red battery warning just after you start the car. If you have no other malfunctions listed, then the red battery warning and "drive to workshop" msg is likely to be a bad aux battery (or, maybe less likely: bad aux battery relay).

If you have the "some convenience functions disabled" msg: This message is triggered if the BCU measures the systems battery voltage to be less than 11V. This triggers the cars power saving mode and the blue message in the mfd. There are two stages of consumer cutoff:
Consumer cutoff stage 1, when the voltage of the systems battery drops below 11V the following functions are deactivated: Heated rear window, memory, interior blower (reduced to 69 %), headlamp cleaning system, seat adjustment front passenger, seat heating/ventilation, multicontour backrest, entrance lamp, exit lamp, warning lamp, steering wheel air conditioning, dynamic seat, stationary heater

Consumer cutoff stage 2. If the systems battery voltage drops below 10.5V, this stage is activated in addition to stage 1 to disable the following functions: Parktronic, trunk lid remote closing, washer fluid hose heater, washer nozzle heater, mirror heater, reading lamp, passenger compartment lighting, footwell lighting, load compartment illumination, rear/load compartment socket, front cigarette lighter, trailer socket, interior blower (reduced to 53 %)

If you have problems with the systems battery for a longer period, you may get warnings also from the aux battery (red warning). Reason: The BCU will not charge the aux battery if the systems battery voltage is below 13.5V. If the systems battery voltage exceeds 13.5V, the BCU will energize the aux battery relay and charge the aux battery if needed. The BCU will only charge the aux battery for a maximum of 20 minutes per ignition cycle.

vettdvr

If you do short driving and your add on system pulls more power than the alt can restore you will eventually have a battery issue. This really sounds like you should try with your addon's removed to see if you still have the problem. Pull the fuses to the add ons and see if you still have the issue.

b_rashed

i havent had any more problems as of right now, but something else is starting. the ac is turned on but nothing is coming out. is this part of the same issue or what?

E55AMGGG04

I just got the battery protection conv. light on today but I left the radio on like an iddiot by mistake while I was playing 3-4 hrs of basketball. Everything was fine at first but then the power to the seats stopped working and the heated seats werent working. I'm wondering what should I do now because I'm thinking that's what got the light to go on?

Polar Bear

It came on because you left the radio on for so long. This is normal. You need to do nothing - it was operating as intended.

starbrite

That's really strange, because I've been in the car with just the radio on and after about 20 min the command displayed a message that if the engine wasn't started, the radio would be turned off. In other words, no way your radio stayed on for that 3-4 hrs.

Polar Bear

Good point, but I guess he could have left the key in the ignition (if he was playing basketball perhaps he did not take the key out to carry with him) and if you don't remove the key, the radio will stay on.

E55AMGGG04

I did walk into the car and the radio was still on. I believe I must have left something on because that's what happened then the battey light came on. On my radio screen it would say low voltage will turn off in 10 seconds...

E55AMGGG04

I just came back from the dealer and they told me that I need a BCU which is $415 and the job is going to take 3 hrs to do and that is what the computer said is wrong but it might be something else if that doesn't fix the problem. I purchased the maxium coverage warranty from chyrsler and they said that they are not sure if the warranty covers that problem but they are going to let my service advisor know in 30-45 minz. This really sucks.

b_rashed

hey guys, so the message came back up today. i havent drove the car in about week and it just started today although i drove the car yesterday. i have no idea what the hell is wrong seeing that the sub i had installed i took out and there wasnt anything plugged in???? i think i may want to change out both the front and rear battery. does anyone know where i could get the one in the front??