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Bought a SL55, Interesting Battery Drain Finding, Need Help
First the back story, A friend of mine told me about a 2003 SL55 that a dealer had that he was friends with. He said he was interested in buying it and wanted me to look at it with him. I said no problem, let’s go check it out. The dealer said that he would sell it to for what he paid on trade in for $8300 (It had been on his lot for a few months, he was not really actively trying to sell it) I asked the dealer what was the story with the car. The dealer said he took it on a trade from the family that owned the car. Supposedly the previous owner had died, and one of the family members traded it in for a truck. We checked it out, the top and windows did not work, the dealer was told by his top notch Mercedes mechanic that he thinks that the windows and top will need to be reprogrammed by the dealer. The car had 88K miles on it. It ran and drove good during the initial test drive. The ABS light and the consumer’s battery being off line were the only real problems that were showing on the info center and instrument lights. My friend had and decided that it was not what he was looking for based upon the problems with car (he is not mechanically inclined). We called it a day. I started to look into all the possible issues that are generally known with the R230 chassis. After doing that, I figured that the rear battery was probably the problem with top and windows, (I made no mention of that to the dealer). The tires looked fairly new, the front bumper cover has scuffs and is missing the passenger fog light mesh grill (I will definitely repaint it before install the new grill).
So, $8000 later I got me a SL55 with 88K miles and no obvious major issues, or so I thought. The problem is not mechanical, it is electrical. The battery in the trunk was dead and bad, it would not charge. So I installed one year old H6 battery from my C300. Good news, everything worked. I started to clean the interior that afternoon. The next morning the battery was basically dead. I was reading about 4 volts. The car is stock, so I thought that maybe the systems that cause these batteries to not last very long were taking a toll on the one year old battery (non-AGM).
I bought a “smart” Schumacher battery charger from Walmart and tried charging the battery again so I would know when it was 100% charged. I bought a new AGM battery, same results, dead battery overnight, drained to about 4 volts again. I checked the drain and it was about 3.5 MA. So I started to trace down the drain by pulling fuses and checking for a drop in MA. Good news, found the system, it is the phone circuit. The drain dropped to about .55 MA, still to high, but a whole lot better. I started the car, and the SRS, and SOS lights in the instrument cluster stayed on, and there was no sound from the stereo. I plugged the fuse back in, everything returned to normal.
Another problem cropped with the fuse being pulled and the car turned off and key removed. The SOS light in the instrument cluster and the cluster stays lit up like the headlights are on.
Circuit 76 is listed valid for this:
Valid for code (855) TELE AID: Fused via circuit 30 connector sleeve
(Z4/3): D2B telephone and TELE AID transmitter/ 7.5 receiver (A35/17)
Valid for code (853) standard MB telephone: Fused via circuit 30 connector sleeve (Z4/3): D2B telephone transmitter/receiver (A35/13)
Valid for code (852) complete portable telephone preinstallation at dome or for code (854) MB telephone:
Telephone interface (A34/4) E-net compensator (A28/3).
So, if the circuit is only for the phone, why the extra problems, like the SRS light on, and the instrument cluster staying lit up? I get the SOS thing going on. I assume that the drain would drop to less than .30 MA if the the instrument cluster lighting would not stay lit up.
The problem appears to be this circuit (it was one of the last fuses I pulled)
Any recommendations to try and remendy this issue?
Mike,
Here attached is the schematic, some good fun reading for you.
You will see that the Tele aid is connected to many other modules in the car (Comand, phone, etc, etc.) so to disable it you need to pull the fuse AND code it out with a Mercedes SDS (Star Diagnosis System).
So the question is, do you have a SDS?
Thanks David, looks like there is alot more involved than a simple phone and a SOS button. I noticed that there is another fuse (16) that is tied to the system. Still wondering why the SRS light is on when the fuse for the phone is pulled. I think I will pull fuse 16 (the other phone fuse) and see what happens.
I do not have SDS, was looking to purchase one of the "aftermarket" software programs to work on the Benz.
Any suggestions?
Yes, F16 is also for the Tele aid.it should be in the left fusebox under the bonnet (HOOD to you guys).
If by "aftermarket" you mean something like Foxwell or iCarsoft, then be aware that these are good at reading codes but not so good fore coding so might not be much help to you.
SDS is basically a laptop (Dell D630, E5500, E5510 or similar) and an interface (multiplexer) a few types available (C3 is RS232 / Serial interface or C4, which has WiFi) plus the Mercedes Xentry DAS sofware which you can find on the Interweb.
SDS is obviously the most capable and complete solution.
Still wondering why the SRS light is on when the fuse for the phone is pulled.
The phone is integrated with SRS, so when you pull the fuse SRS sets a fault for loss of communications with TELE AID.
Originally Posted by DavidCA
...plus the Mercedes Xentry DAS sofware which you can find on the Interweb.
Apart from this download from my OneDrive account, are there any others you know of, or can you suggest a way to search? Peter (pmercury) had a link but is no longer offering the software for free.
Nearly everyone purchases a multiplexer and cables from aliexpress.com. A C3 type is about $200. Even though Star Diagnosis is free, I suggest adding to your purchase a hard drive with pre-installed software. This way you can have the parts catalog, WIS, and the very latest version of the diagnostic software.
I have a Foxwell with ABS, it is good for reading codes and realtime data, however it would not find the ABS fault. And yes, by "aftermarket" I am looking to purchase a program and cables to be able to login into to the computer and make fixes. Just not sure which one to buy.
If you don't expect to diagnose a c. 2014 or newer M-B anytime soon, then a C3-type multiplexer may be your preferred choice. For $200 you can get it and the required cables from alixpress.com. Try to find an offering which includes the software on a hard drive for c. $50 more.. On Aliexpress "xentry" is a good search term to find what you seek.
Last edited by bobterry99; 05-05-2020 at 09:31 AM.
Your reported battery drain current measurements, .55 milliamps to 3 milliamps (ma) appear extremely low to me and should not result in a dead battery, even over more than 2 months of storage time. In my experience, a reasonable long term current draw for an occasional use car that does not "eat batteries" is about 20-40 milliamps. With that said, my new (to me) 2004 SL600 does "eat" a 4 month old trunk-mounted consumer battery overnight, but it has a much higher (and unacceptable) current draw, with no lights on of any type and the key out of the ignition. Here are my recent test results (repeated two times on my SL 600):
Time 0 (car driven normally just prior, no dash warnings) Not running battery voltage 12.6 volts trunk open trunk light on-- current draw 4.46 amps (4460 milliamps)
Time 1 minute later (with trunk lid now closed). current draw 3.76 amps
Time 2 minutes later current draw 1.63 amps
Time 4 minutes later current draw 1.30 amps
Time 5 minutes later current draw .80 amps (800 milliamps)
Time 5.75 minutes later current draw .48 amps (480 milliamps)
Time 6.00 minutes later current draw .19 amps (190 milliamps)
Time 8.00 minutes later current draw .16 amps (160 milliamps)
Time 10.00 minutes later through 30 minutes later (end of test) current draw .16-.20 amps (160-200 milliamps)
The timed observations/measurements above coincide with each change in current draw at the stated times. Obviously, there are some electronic gremlins living in my SL600, as a long term current draw over 40 milliamps or so will drain even a new battery. For now, I have installed a battery shut-off switch on the negative terminal of my consumer battery. Since I don't have any advanced diagnostic equipment other than my trusty voltmeter/ammeter, I will pull some likely fuses to see if I can get my car's current draw down to something reasonable. Any tips from other owners/mechnics would certainly be appreciated in the meantime. Before anyone asks, my engine compartment battery seems just fine, with an at rest voltage of 12.5 volts. I didn't take any current draw measurements of that batttery.
Just a note, there are several things on the car that will drain the rear battery when parked. I'm not driving much now (out of work due to COVID stuff) and I get a "convenience features not available" warning until I drive it a while or charge the rear battery. Some owners use a trickle charger.
Good luck with your problem!
Mangusta, maybe I had I was off of a zero on my setting. Unfortunately the car is still basically down, battery lasts a few hours when connected. I guess I am the only that has had the phone (or lack off) be the cause of killing the battery.
Oh well, should have known better to a Benz. Some day I will figure it out, actually I found the problem, just don't no how to fix it.
Thanks for your response. Next week, I'll run some longer term digital current drain tests (5 or 6 days, hopefully) to see if my parked SL600 current drain is decreasing below the level that I reported after a 30 minute shutdown period. I did check my consumer battery voltage level after a recent 5 day test and it was still "OK" at 12.36 volts, so I think some more computer-controlled circuits shut themselves down after my previous 30 minute test period. However, the important tests are accurate current drain measurements over a multiple day period.
To eliminate a weak battery being the cause of your rapid discharge situation, I'd suggest taking your consumer battery of the car and have a free battery load test performed on it at a local Autozone or O'Reilly parts store. If the battery checks out OK during the load test, the standard mechanic's test approach to identify current drain culprit circuits in a vehicle is to sequentially pull fuses one at a time while measuring the current drain (in Amps or MilliAmps) from the battery with a digital ammeter. But this test is time-consuming and difficult to perform on our complex cars because of the large number of fuses involved and the number of computer controlled devices in these cars. Good luck with your troubleshooting and I will report back my longer term current drain measurements to the forum.
I am resurrecting this old thread, as I can report a workable solution to the R230's problems with periodic battery drain problems for the trunk-mounted "system's" or "consumer" battery. Since my SL600 frequently may go multiple weeks without being fired up in my storage facility and that storage facility does not have continuous AC power available in it, I needed a better solution than the typical "just put a smart charger on the system's battery". After purchasing several cheap battery disconnect switches from the internet, I finally found a unit that would fit on the negative terminal of the trunk-mounted system's battery in the limited space of my 2004 SL600. This unit allows me to easily disconnect the system's battery from the car's electrical system during non-op periods.
By disconnecting the system's battery negative terminal from the car's chassis using an inexpensive temporary battery disconnect switch, I have eliminated both periodic battery drain problems and any chance of a trunk fire caused by a failed battery control module (BCM), as reported by some forum members. At this point, I have approximately 8 months of "no problem" service time on this simple solution. Since my parking space is secure, I can leave my trunk lid un-latched after I twist the battery disconnect switch counter-clockwise to the "no power" position when my car is likely to be parked for more than a few days. When I need to start the car, I just raise the trunk lid manually, twist the battery disconnect switch clockwise to the "power on" position, gently close the trunk lid (so the electric pulldown motor takes over), and hop into the car, start it, and drive away. I have not had any problems with dash alerts, nor have I needed to re-sync windows or power steering, or even reset the OEM radio's station settings, despite multiple absences or 3-6 weeks and one long absence of a little over two months during my almost 8 month test period (since June 2020). I do not disconnect my engine compartment starter battery in any way.
Last edited by mangusta1969; 02-06-2021 at 01:11 AM.
Reason: Correct a typo
I am resurrecting this old thread, as I can report a workable solution to the R230's problems with periodic battery drain problems for the trunk-mounted "system's" or "consumer" battery. Since my SL600 frequently may go multiple weeks without being fired up in my storage facility and that storage facility does not have continuous AC power available in it, I needed a better solution than the typical "just put a smart charger on the system's battery". After purchasing several cheap battery disconnect switches from the internet, I finally found a unit that would fit on the negative terminal of the trunk-mounted system's battery in the limited space of my 2004 SL600. This unit allows me to easily disconnect the system's battery from the car's electrical system during non-op periods.
Mangusta, Can you share the source for that Battery Disconnect Switch?
I bought it on amazon.com. The reason I posted a fairly detailed photo with the switch attached to my system's battery is that there is very limited mounting space on my SL600 and I wanted to show members what it looked like. I purchased my disconnect switch on Amazon for about $8 almost a year ago. However, I'll look through my Amazon purchase records from last year to see if I can locate the exact switch that I purchased, but it took me several switch purchases before I found a switch that could fit in the very limited mounting space. I'll post back anything that I find. The installation of this switch definitely solved a big problem for me, since my car's storage location does not have full-time AC power.
Hopefully, I have just attached a detailed photo of the disconnect switch that I used on my SL600. Amazon says it is "no longer available", but I have seen other switches like this in auto parts stores (and maybe on the internet). The rotating feature for the male post is quite critical, as I had to partially rotate it so that I did not have to modify the SL600's OEM battery grounding cable. Good luck and report back if you find a current source for a switch like this. I will do the same.
Hopefully, I have just attached a detailed photo of the disconnect switch that I used on my SL600. Amazon says it is "no longer available", but I have seen other switches like this in auto parts stores (and maybe on the internet). The rotating feature for the male post is quite critical, as I had to partially rotate it so that I did not have to modify the SL600's OEM battery grounding cable. Good luck and report back if you find a current source for a switch like this. I will do the same.
I just looked at a number of auto parts store web sites and could only find one source for a similar switch. Although this switch is NOT available in local stores, www.walmart.com displays an identical battery disconnect switch for $9.35. Just search for "battery disconnect switch" on the Walmart web site. This switch is available there for $9.35. I hope this helps someone.
FxFormat, sorry, but the straight style switch you linked (just above) from Amazon.com would not fit in my 2004 SL600, due to space limitations and the short cable length of the original negative ground cable in my car. The right angle rotating style switch that I linked earlier was the only one that worked for me.
Last edited by mangusta1969; 02-07-2021 at 03:09 PM.
Reason: accuracy
"...Since my parking space is secure, I can leave my trunk lid un-latched after I twist the battery disconnect switch counter-clockwise to the "no power" position when my car is likely to be parked for more than a few days. When I need to start the car, I just raise the trunk lid manually, twist the battery disconnect switch clockwise to the "power on" position, gently close the trunk lid (so the electric pulldown motor takes over), and hop into the car, start it, and drive away.... "
Great solution! You can still lock up the car using the Mechanical Key to lock and unlock the trunk. It will also work on your door.
My Grandfather would always put a cut off switch to the battery underneath the dashboard of his vehicles, but that was way before all the technical gizmos on cars these days.
"...Since my parking space is secure, I can leave my trunk lid un-latched after I twist the battery disconnect switch counter-clockwise to the "no power" position when my car is likely to be parked for more than a few days. When I need to start the car, I just raise the trunk lid manually, twist the battery disconnect switch clockwise to the "power on" position, gently close the trunk lid (so the electric pulldown motor takes over), and hop into the car, start it, and drive away.... "
Great solution! You can still lock up the car using the Mechanical Key to lock and unlock the trunk. It will also work on your door.
My Grandfather would always put a cut off switch to the battery underneath the dashboard of his vehicles, but that was way before all the technical gizmos on cars these days.
Brian A.
You can add a battery cut-off switch where you want as long as you thick enough cable
it's just a matter of some simple calculations
One other thing to consider: If your SL is parked for a month or more, perhaps you should put Sta-Bil in the gas tank. I had major problems with my motorcycles when I had to park them for a while, the ethanol gas we get now really sucks and would gum up the carburetors and injection nozzles. When I stared using Sta-Bil, the problems went away.
04-30-2020, 01:51 AM
