Help - Flat Battery! Is it a known issue!

[Ryann]

Hi,

My CL500 battery went flat the other morning. Nothing would work. I could not even open the door with the key. Called the AA and they jump started the car. The guy checked the battery and said that it was a healthy battery. We assumed that the battery may have drained because I may have left the lights on Auto. I am not even sure if I did leave the lights on Auto. I assumed that if I switched the car off the lights would go off anyway.

Secondly, the battery went flat today. This time I definitely know I did not leave the lights on Auto. It is a healthy battery and something is clearly draining it. I did a Google, and came across other CL500/CL600 owners having the same problem. Does anyone know if this is a known issue! Some of the info online is saying it is PSE Pump? Others are saying other things.

Has anyone come across this issue before. If so can you help me please.

 

[colechelle]

Yes seen it quiet a few times, most common thing is the command draining it, also seen faulty door control modules draining, disconnect neg terminal, put a muti-meter in line on battery, close the boot latch by hand and lock the car, should with-in 10 mins drop to around 00.08ma, if it dont then your going to have to start removing fuses one at a time to find what is draining it, simple to trace!!

 

[Alfie]

If your CL has comand 2 in it then it could be that.

When you turn the comand on do you get a Mercedes Logo on the screen?

 

[Ryann]

Hi Guys,

Thanks for your prompt response. My car has Command but I don't use it. Then again I am not clear on eaxctly what command does. Newbie here. However, the TV, Sat Nav screen thing (I am assmuning that's what you mean by the command device) display the merc logo when you turn it on to play CD's/TV/Sat Nav. It has a Bose Sound system with CD Autoloader. Could it be th sound system.

What is a "put a muti-meter in line on battery" and where do I get one and how much does it cost?

If I could resolve it myself, it would really help, as this has happenned at the wrong time.

Thanks all.

 

[colechelle]

you can buy a cheap muti-meter from somewhere like halfords, put it on amp setting, connect one line to the battery, the other on the neg terminal so the battery power to car is going through meter, then follow my last steps, very easy to do!

 

[Ryann]

OK. Thanks for your help.

I contacted Halford and I will try and pick one up tomorrow. Secondly, if it is a fuse then, what is the average cost of replacing a fuse?

 

[colechelle]

sorry, i meant you have to pull each fuse one at a time to see if the drain drops!!

 

[Ryann]

Hi, I bought the Multimeter from Halfords. I am going to try and test it tonight. The car needs to be off when I do the test right?

Note for other readers, don't buy a Multimeter from Halfords. You can get it half the price at Maplin. I made a mistake for not checking.

 

[colechelle]

yes boot latch in locked place and rest of car locked, leave the meter in place for at least 10min before reading!!

 

[star]

Be careful not to destroy the multi meter by loading it too much, ie use over and above the normal 10 amp rated multimeter.

 

[Ryann]

Yes seen it quiet a few times, most common thing is the command draining it, also seen faulty door control modules draining, disconnect neg terminal, put a muti-meter in line on battery, close the boot latch by hand and lock the car, should with-in 10 mins drop to around 00.08ma, if it dont then your going to have to start removing fuses one at a time to find what is draining it, simple to trace!!

Hi colechelle

I am just about to follow your instruction, please can you verfiy that I have to disconnect the neg terminal from the car battery and then proceed to connect the mutlimeter to the battery. many thanks

 

[Ryann]

One more thing. Is positive the red one?

 

[BlackC55]

Yes.

You may have to wait longer than 10mins. Leave for up to at least 20mins to be sure.

A long winded job that one.

 

[colechelle]

yes sorry, just see it a CL, that will take longer to "go to sleep", put that call in at 8am olly in morn, have the kettle on about 08.45!!!

 

[Ryann]

Hi All,

Bad luck I am afraid. We couldn't disconnect the battery. Did not have the right tools.

I know it's not the battery or the alternator (from what people are telling me). Something is draining the battery. I will try and take it to a garage this weekend. Estimating (probably hard to do), how much to diagnose and fix something like this?

 

[colechelle]

you dont have access to a 10mm spanner!!!!!

 

[Ryann]

I have a standard spanner. With that it was very difficult to unscrew it. It was very tight and there was no grip and we were wearing out the bolt. I didn't want to cause more damage. In the end I thought, so long as it doesn't cost too much I will get the garage to take a look.


I left the car at garage after work today. I'll know Monday the cause/result.

 

[colechelle]

from memory the cl has a half decent tool kit like the s,class, should have a 10mm in there!

 

[Ryann]

Hi All,

The garage confirmed that it is the command. For the moment I have taken the fuse out for the command. If I drive it with the fuse in so that I can use the CD player then take it out when I park then it shouldn't really drain the battery, right?

Also, how much is a second hand command system and where can I get one?

 

[colechelle]

Hi All,

The garage confirmed that it is the command. For the moment I have taken the fuse out for the command. If I drive it with the fuse in so that I can use the CD player then take it out when I park then it shouldn't really drain the battery, right?

Correct!!