Hey Guys,
Can anyone help me with my 2003 clk500 amg- just lately when I start my car I'm having to get a jump every other day. If I leave my keys in the ignition after turning the car off, it won't start and I have to get a jump. Batter is fine and nothing is showing on the diagnostic I had done at Auto Zone. Hoping someone can help me narrow the problem down before I take it in. Could it be electrical because sometime when I turn my car on instead of the radio playing it just gives a ticking sound? And my seats have a mind of its own - but rarely.
Any suggestions would be appreciated.
Thanks

 

Check your power seat, 2 years ago, mine would keep trying to retract the seat after I left the car and it would drain the battery. I pulled the fuse for the seat, boosted the car (again) and it was the culprit.

 

Thanks for the tip, but since my radio is sometimes affected also, I'm not sure if this will completely solve the matter.

 

Do not leave the key in the ignition. It energizes the EIS and that could be causing the drain. Also, a dead battery with the key in the ignition could kill the key.

 

Thanks Rodney...I will remember that....

 

Bumping for any other suggestions. The clock was also going round and round even after the key was taken out of the ignition. I'm taking it in this week...but I would like to kinda know what I'm dealing with. This being Christmas time and everyone seems to want presents at this time..especially auto repair shops..lol...

 

Honestly, I am not sure I would trust Auto Zone on the battery check. What is the voltage at rest? If it's below 12.6v, then I suspect the battery is bad.

 

I'm battling this issue now (2004 CLK500)! The first symptoms I saw was the slow startups (cold or warm), the warning "Light Sensor Visit Workshop" and the dome light in the trunk did not want to light up (after a few hours of the trickle charger, this light comes back so the electronics must be saving power when low).

My battery couldn't hold a charge after recharging (I charged it, went to the store and then the car wouldn't start), so I had MB roadside assistance get me a new battery; but I don't think the battery was the root cause.

So I bought a multimeter and starting doing some research online. I first suspected the seat modules (W203ers have a similar "drain" problem), so I took a look at their quick fix (which is to splice the Power constant and tap that line into the accessory line) and found that my Seat Module does not have 3 wires (Brown, Red, Black) like the W203 cars, my car only had Brown and Red; so I couldn't do that quick fix (although I plan on doing the Relay trick later). I pulled the fuse on the seat modules and checked the current draw on fuse 27 (driver side, no current draw found) and fuse 34 (passenger side, found a 20ma draw) and found that the passenger side was drawing current where the driver side didn't; so I just disconnected both seat modules power clips until I finish finding the root cause of the issue (car runs fine with no SRS faults). I also checked the current draw from the dome light (fuse 9, the sensor here is know to be faulty too), but found no draw.

I'm not sure where to go next. I can check the alternator (was 14 volts when the new battery was installed, then went to 13.5 volts@idle after 40 minutes of driving) and other accessories, but I don't know how to check those items on a Mercedes W209 (I don't know the proper procedure and I don't want to damage anything). I also know there are "idle" voltage and "sleep" voltages, but I do not know the schematics of the proper ranges or the best way to test for both scenarios.

I can do the leg work if someone knows a few good DIY electrical troubleshooting on a W209! I will definitely report my findings.

 

It was 12.65V.....Good point...

 

[I]2MCHCAR - Thanks for the input..I tried to purchase a new battery but they told me mine was okay b/c it is almost 3yrs old. I will get one though..but like you I think there's more to it. I can't get an appointment until Wed. but I will let you know what we find out them. Have you had starting problems after replacing your battery??

 

My "Old" Mercedes Battery was dated 03/10 (little over 3.5 years old), so I thought it was strange that it died so quickly (the original battery lasted 7 years). I do have a Super Charger (with a big heat exchanger pump CM90), a Big sound system (aftermarket radio with 2 AMPs), and running a Radar Detector from the cigarette lighter; so I may have too many things running at the same time. Also, I have had car issues like a bad fuel pump and we were cranking a lot trying the diagnose the root cause (may have drained the battery at some point).

I bought my new battery today, so I haven't had the overnight test yet (my seat modules are still unplugged). I did start it twice since it was installed and found no problems (starts like a champ). I will update this thread tomorrow and let you guys know how it went.

BTW, 20,000 Miles ago I replaced my voltage regulator so I don't think it's that. I have found two PDFs online about troubleshooting electrical problems (attached to this post), so I plan on getting this problem sorted out during my two week Xmas vacation.

I'm just hoping that our Gurus Rudney or Glyn Ruck could chime in and perhaps brainstorm something I'm over looking or have not considered.

I have done several DIYs for this forum and I wouldn't mind making one more for this difficult issue.

 

Another thing that draws current & flattens batteries is the HVAC sniffer fan in the overhead console not going to sleep. I do not know whether that operates via fuse 9 or 41 & 51. I would measure HVAC fuses 41 & 51 for abnormal quiescent draw.

 

Thanks Glyn, I'll make checking fuses 41 and 51 a top priority!

Here is a timeline of the past two days:

• Replaced my almost 4 year old MB battery, with a new MB Battery I bought from MB Roadside Assistance.
• With the new battery, car started right up (no slow cranking); I didn't see the "Lamp Sensor" warning either. When I got home and turned off the car, I noticed my trunk interior light works (it will not turn on if you have low voltage ).
• I unplugged the Seat Modules, took note of the resting voltage (12.7V; took this value from the Dyno Mode display), locked the car like I always do (with the key fob) and left it overnight.
• In the morning (I hate that feeling when you think your car will not start up) I took note of the voltage from dyno mode (12.7V), then started to car. The car started like a champ and I took note that the voltage with the motor on is 14.2V, then slowly worked it's way down to 13.8V after a 30 minute drive.
• The car sat for 9 hours, then I checked the voltage at rest (12.7) and drove for an additional 30 minutes. The running engine voltage range was 14.1-13.8, found no issues during the drive. Parked the car, took note of the voltage (12.7V).
• I then reinstalled both seat modules wiring harness, locked the car and crossed my fingers. The car sat for 9 hours.
• In the morning, I checked the voltage again and it was 12.7V! Car started like a champ, the running voltage was rock steady at 14.1-13.8V.

Thoughts:
I'm beginning to think that the problem really was the battery. The alternator is pumping the right voltage, the voltage does not drop overnight, and all the little electrical problems I've been having (Stereo Amps would cut out when turned up, the radar detector complained of low voltage sometimes, and the interior trunk light did not work) has gone away.

The previous battery was getting old (4 years) and had a hard life (no long distance driving, had to endure my supercharger and fuel pump issues, ect); it would charge quickly then not hold the charge after one drive. In hind sight, I was having these "little" electrical issues for months, but this time the car wouldn't start. I think one of the 2.1V cells in the battery was getting weak, then finally died.

Anyways, sorry for the long post. I will continue monitoring the situation and giving updates.

 

My 2005 C230K is at the shop now for various service items. The service mgr called and said he recommended a new battery because the resting voltage was low. I said it starts fine. He said that the low voltage would start to affect other "things" and would probably manifest in CEL's . Ok, it's the original battery, no issues replacing it after 8 years. He then said the battery needed to be coded to the car. . .? Not doing that would dramatically reduce the life of the battery? What's this about? A necessary thing or to keep me from going to Sears and getting a Die Hard?

 

OMG, that's such , the service adviser is lying to you! There is no coding required when you change a battery, he's just trying to charge you more labor time! Do yourself a favor and don't reward their deceit by getting your car serviced there; pay for their "Diagnostic Time" and get your car out of there! Cut your losses, if they were ready to rape you for a battery, I can't imagine what they'll quote for actual repairs. Get the list of what needs repaired (cause you paid for it) and take it to a local "Independent" Mercedes shop (you can ask your W203 brothers where they get serviced in your area).

As for a battery, that's the only thing I can agree is correct. 8 years is great for a battery, but it's time to change it out. I would bet most of the issues you are seeing are related to the low battery charge (that was the case for me), so get the new battery first and see if your problems go away. If you have spent $100 and over at a Mercedes dealership in the last 18 months, you can have Mercedes Road Side assistance get you a new Mercedes battery and they will drive where you're at (at your house for example), install the battery for you, reset all the components (sunroof, windows, etc), and haul out your old battery. The best part is you will only pay for the battery and not the labor. If you go to the Mercedes Stealership, they will charge you for the battery and the labor (.5 hours @ $120-$140 hr). Good Luck!

As for me, I checked my voltage in the morning and it's at 12.7V (it was the same when I got off of work). So I believe I don't really have a battery drain issue, it was just the battery. I will continue to monitor the situation and if anything changes I will update this thread!

 

Thanks, I think. . . I really wasn't having any issues, (other than a CD that won't eject) I simply received a notification on the dash message center telling me that 120K mile Service "A" is due. The shop is an authorized service center, not one of the big Seattle area dealerships. And yeah, I paid for a diagnostic readout and then an inspection. The only thing the diagnostic mentioned was cabin air filter and plugs. The inspection revealed the battery thing and they also recommended a brake fluid replacement.

 

Got it. You can do the cabin filters yourself (I'm assuming you mean the filter in the dash and not the one in front of the battery, I'm sure the W203 DIY section has a thread) in 20 minutes and the filter costs around $30. If the plugs have never been changed, then it would be a good time to do so. I also agree with the brake fluid change and battery. One more thing, if you haven't done a transmission fluid change; add that to your list too.

 

UPDATE:
I had my car turned off and had the alarm on for 60 hours straight. When I checked the voltage in Dyno Mode, it was 12.6V! No battery drain issue.

 

Hey guys had the same issue with my car. Interesting fix turned out the negative terminal was providing heavy resistance due to the many years of croatian on it just another thing for you guys to check