Still sorting through various issues on my recently acquired '03 SL55. I've been fooling with the 'Consumers Offline Message' for awhile and am close to buying a new Vehicle Power Control Module (eeek $600+). But am trying to gain confidence before making a bad decision. This module is variously call the Battery Control Module and Power Control Module etc. and is located in the trunk near the back of the right wheel well. I see there are one or more p/n upgrades and no used parts out there so it seems to be a chronic failure point??

My STAR DAS gives me code B1832 "faulty starter battery". Both batteries are new, the Starter Battery is MB OE, and the Systems battery is a premium Gel from Napa. They both have near full charge as judged by putting my smart trickle charger (normally on the systems battery) on either; it quickly turns OFF indicating full voltage of 13.9-14.1V or so. I also had the Starter Battery checked at the local tire shop (not a full load test like I've seen before) his hand held tool indicated 773 CCA and no bad cells.

Other symptoms: It will barely (sometimes not at all) recover the consumers after a 10 mile drive, or two 10 mile legs. Recently it wouldn't unlock the doors (luckily the window was down), sometimes the trunk won't open with the key fob, and lately after clearing the battery fault code, I started have trouble starting it - I'd get a red dash message "release brake pressure and the start" or something similar. Fiddling around seems to overcome the problem......but its pretty erratic.

Also after such an event, and 10+/- miles, I checked STAR again, no fault listed for this module (possibly not soon enough to re record it as I'd cleard it 20 mi before and 4 ignition cycles) but with the ignition on, engine off, STAR showed 8.9V!!!

Alternator seems ok as with engine on, I'm getting 14+/- volts.

Any ideas? Help appreciated.
MK19

 

Battery control module is probably on the right track. It appears the consumer battery simply isn't being charged or charged correctly and the system isn't seeing that its charged. Once these cars notice low voltage all kinds of warnings can pop up. Have you taking the BCM out and opened it up yet? Some have and they have looked almost burned on the inside but are still operating. They usually smell also.

 

Excellent idea Sky......I don't know why I didn't inspect the BCM, other than its a pain to get at it. But I have now and it's in nice shape to both the eye and the nose, inside and out. The low voltage connector pins and sockets look good too.

Hmmmm, still puzzled and reluctant to have a $600 spare laying around.

You'd think it would throw a code if it was bad? Looking for others experiences here.
Thanks

 

I like to wrench on my own cars also but when it comes to goofy unexplainable electrical things I've learned through the years it's better off paying a good Euro Indy shop to track down the issue if I can't figure it out over a day or two. In some cases it's literally like one hour of labor for like $100, I don't believe I've ever been charged more than about $250 to figure out an issue. You can be pulling your hair out for weeks trying to figure it out or throwing money at unneeded parts all of it cost more than a professional to just take look at it. You don't have to have them repair it.

They also will be much more familiar with the ins and outs of Star software.

 

I have had both batteries fail (gradually and otherwise) on my 2003 SL55 during the 9 years I have owned it and had a few odd symptoms, but not a list that compares to yours (so it would not shock me if you have a bad N82/1, battery control module). I have had codes for a bad battery control module, but they cleared or went away and have been absent for years.

I did NOT see where you had your consumer battery load tested (perhaps you did and I missed it). This would be my next step if you have not already. The consumer battery always seems (in my experience) to fail gradually, but symptoms ramp up near the "END" (I had to replace it a year after I got the car and twice since then).

This load tester is regarded as accurate and is less than $50. I have used it many times on many vehicles (but mostly my SL55 : ) and am glad I got it.
If you have not seen this PDF (below) from Mercedes (part of their technician training docs?), you may want to take a look at it as well.

HTH,
Chris

 

and I forgot to mention that you may want to check the right-rear vario-roof "drain tube" (right front corner of truck area) to see if it is disconnected or plugged//broken. If the drain tube is not working properly, water from the outside can run into your battery control module.

Chris

 

Those are excellent suggestions Chris, and thank you again for aiding me in this saga. The drain tube looks fine but I'll check it again. No corrosion or signs of moisture intrusion at all.

In fact the load ck. on the rear batt has not been done......my assumption was that this 3 mo. old 760AH Glass Matt Batt was good. However, as mentioned I'd planned to clear the faults and put some miles on. I did that and the consumers were back on line 6 miles later. I put 70 miles on it that day with the first and last of several legs of about 25+ miles each. Intermittently I'd check the top, getting very mixed results. Besides the "consumers off line" message, I also get "review your operators manual" (or similar) when the top won't operate.

After those 70 miles, I rolled into the garage and hooked up DAS, and all kinds of modules were showing low voltage and other faults (nothing on the BCM however or batteries). Curiously my MultiPlexer always seems to have a "check batteries" message in its' window?? In the course of this and after clearing these codes and retesting, I shut the car and within minutes I had under 9V on the rear batt. So it sure seems like that new batt has no legs. I'll have it load tested today.

Fingers crossed, more to follow.

 

I didn't notice that you mentioned it, so I thought I'd ask.
When you have your star-tester connected, do you have a proper charger hooked up ? (or have the motor running?) . I have a variety of chargers (4-5?) and found that I need 20amps or better to keep up properly when on the star tester for a "quick test" or more. I bought this one (see amazon link) over 4 years ago and it is my favorite (and only cost $60). It charges at 25 amps (seems to work great when on the STAR) and it has "starting" and "battery recondition" features (both of these features seem to work well, but I only use them on "other" vehicles, not my Mercedes). I make sure that the voltage is over 12.6 v when on the tester (I'd be worried if it were below that).

Also, worth mentioning, every Mercedes I've owned has had the alternator fail at least once. And luckily for me, it was always just the regulator. However, when I replaced this (normally after a hard-fail, but once or twice after flakey-fail) I would find that the brushes were worn down to the point of compromised contact (hence the flakey fail, I assume). Perhaps you are having a "flakey-fail" issue?

 

Hi Chris,
I don't have more than about 8A on my charger, which isn't enough so I have to run the engine. With that I get 13.9 to 14.4V at the DAS and at both batteries. I'm told DAS will pull the batt down pretty quickly, but you'd think with over 700AH capacity it would go for more than a few minutes. I note that the DAS gets pretty warm so I know its consuming a fair amount of power.
Flakey Alternator: Possible but it seems the starter battery never fails and I've never seen the voltages float more than about the 0.5A I mention above. But that might be a next step before leaping off the BCM $$cliff.

More to follow.
Any thoughts on my latest post re ABC controls Chris?
Thx,
MK

 

Yep Chris, good call. Rear battery despite being a premium NAPA AGM new in May is shot. I won't have confirmation that all is well until I get the new batt in and spend some time with it, but it certainly is part of the problem. Will update you when I'm sure of the fix (or not??).

 

I just went through the same issues on a friends 2007 SL550, a like new rear battery (6 month old O'Reilly AGM) would charge up fine but by the next morning would not have the capacity to run any of the consumer items on the car. One of the culprits of causing it to run down so fast was a short in the PSE pump.

After the PSE repair/exchanged with an other unit and the battery exchanged with a NC under warranty unit from O'Reilly all the consumer not available issues are gone.

 

Hopefully replacing this solves it (if nothing else, you are closer to getting this sorted out).

As I have 3 daily drivers (that sometimes sit for a while between use), I have to keep a close eye on batteries (and their warranties) . So, I have gotten in the habit of taking the receipt for the battery and sealing it in a thick plastic bag, writing the date when exchange and/or warranty period ends (on the plastic) and then taping it to the top (or side) of each battery. Then, I make a point of testing it with the load tester (linked in post #5) as this date approaches. It is not unusual for a battery to still function, but be out of spec.

Cheers,
Chris

 

YES!!!!!!!! finally. New rear battery seems to have solved it, and the center dash clock now sync's time with COMAND......so got that bug fixed too.

Hard to believe a new AGM battery went south, but I'm sure it happens.

Thanks all for the help and especially latemodel Chris...…..you nailed it!

 

Hello Hendrik,
How did you determine that the PSE pump was running? Can you hear it or feel vibrations from it? Or was it by measuring current draw?
Thanks,
MK

 

Normally you can check the cycle time duration after the door locks are activated or the trunk shut clamping is taking place a few seconds after the trunk is closed [this applies to manual and power closing trunks]
In this case continuous running kept blowing the 15Amp fuse in the rear SAM.
I used a clamp meter to watch the Amp draw when I would replace the 15 Amp fuse with a new one and see it blow again after 15-20 seconds.
Most of the time these PSE pumps have leak in the plastic housing which most of the time can be repaired with epoxy in this case the circuit board was bad.

Ones you open them up they are pretty straight forward to repair provide there are no traces of water penetration inside.

Glad your battery issue got resolved now go enjoy your car.

Best H

 

Chris - looks like I need to replace my 2004 SL55 rear trunk battery as I keep getting the "Consumers Offline" error which does go away if I keep the battery on the trickle charger for 1-2 days straight but comes back after about 24 hours when not on the trickle charger.

What replacement battery did you buy? Was it a perfect fit for the trunk mount?

Looks like my current battery is MB OEM A0019828008 with 760A / 12V / 70Ah and it doesnt appear that MB battery is currently available.

I found this 760A battery from Adv Auto Parts which seems to be a direct fit replacement but if you have one you bought that fits correctly let me know. thanks john
https://shop.advanceautoparts.com/p/...920%7CL2*15000

 

Well, there was a time when "die hard" (and sears) were known to be good ... not sure that time hasn't passed (advanced auto parts bought the DIE HARD name in 2019). The last consumer battery I bought for my Sl55 was a Bosch from pep boys ... the first one lasted 18 months (then free replacement) SO, not sure if I could give that a great recommendation.

The next time I buy at battery for this, I suspect I will go directly to Interstate (OEM for mercedes IIRC) here is a link for 3 batts (the first is "starter") either of them would be a good choice I think,
https://www.interstatebatteries.com/...sl55-amg-v855l
Chris

 

... but, since nearly every battery is made by johnson controls (including interstate ) The die hard is likely as good as (the same as) the interstate.

 

Chris you're always amazingly helpful thanks again. I forgot that JCI makes most of these batters so the DIE HARD and INTERSTATE ones maybe similar then. They actually have the same 3 year warranty so cant go wrong with either then.

I have a Adv Auto near by so will give them a shot with the Die Hard.... thx again!

 

Chris - thanks for your help on the battery recommendation. I bought this Die Hard battery which was **identical** in shape/dimensions as the MB OEM one and fit in the trunk perfectly with both brackets installed.

https://shop.advanceautoparts.com/p/...m_content=ITEM

The consumers offline warning is now GONE even while driving with all "consumers" on (AC, Headlights, seat fans, retracting the top) and car is back to normal.... super appreciate your help as always.

 

Glad to hear you got that all sorted.
Oddly enough, I just discovered yesterday that my consumer battery in my 2003 SL has failed again ! In 2017, I had bought a Bosch (great deal it seemed $160 and 48 month free replacement). In 2019 it failed and they gave me a "Champion" 48 month H6 as the replacement and that is made by johnson controls. And then today, they gave me a 48 month "Champion" again (perfect timing as Pep boys looks to be going out of the retail parts business this week). This one has a sticker on it that says, "made in Germany" (guess that is good : ) These cars sure are hard on their consumer battery.

Cheers,
Chris

 

yeah its an eye opener to me how quickly these SL rear trunk batteries get depleted. Do you leave your trickle charger on the rear battery at ALL times? I was doing that on my old battery and that was the only way i could get a few hours use out of the car without the "consumers offline" warning coming up. I'm not super clear on if the rear battery gets charged by the alternator at all or not.... so might just continue leaving the trickle charger on at least 1-2 days per week once this new battery gets to 2 years old.

truly an act of love taking care of an old SL55!!

 

some years ago, I added a magnetic connection for a trickle charger (more info here https://mbworld.org/forums/w211-amg/...ml#post6882041 ) and since then, I have had 2 trickle chargers that both failed eventually (a c-tech and something I got at costco), so not really sure what it up with that, but I've not bought a 3rd yet. So, since this is one of my 3 daily-drivers, I normally drive it often enough that it is not a problem, but when I don't (if it sits for a week or more), I put this charger on it which both charges at up to 25 amps (useful when on the star tester) and automatically switches to "float" charging when the battery is fully charged.
Cheers,
Chris