Can someone please help me? (CL Electrical Issues)

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The rear battery powers everything (other than starting) in the CL if the battery gets low, almost everything becomes glitchy and stops working, and all sorts of electrical warnings are displayed, and fault codes saved.
It's not easy to get at the rear battery, I remove mine to charge it and swap another in temporary, Make sure the battery is fully charged and holding, everything will start working correctly, but you will still have problems with windows, warning lights etc until everything is reset.
Also sorry, when you say everything needs to be reset, is that something I can do with a simple code reader? Or is a trip to the Mercedes specialist required?
 
As mentioned previously.

On early CL's with serial numbers < 004585 the ABC controller has the bug that causes it to malfunction and NOT
go into sleep mode properly if the vehicle is not "gotten-out-of-and-locked-within-60 seconds"

Disconnecting a battery connection and then inserting an Ampere meter is not a recommended way
to hunt for this as some other control units will not be properly awoken and synchronized in the
power-up/down/up sequencing. One thing to know is that this platform (also S-class 220) never got
stable in terms of software. It does not take much for a Xentry to write a novel of error codes
of which many are non-essential and can be disregarded. Mercedes themselfes decided
to make many of them "transient" that is, if the engine is turned off and later restarted
the DTC is cleared. A check-engine message can go away for instance. But not DTC's
set by the SRS...

The recommended way to check battery drainage is to purchase a clamp-on Ampere meter
that can read down to milliamperes. Then, after a drive, open the boot, click the lock
on the lid (fooling the system that the boot is down and in position). lock the rest
of the car and attach the clamp-on meter to one of the battery connecting cables.

Then, fetch a mug of coffee and look for the readings to drop as system after system
shuts down. You will be watching some quite high currents at first that stays on for
10-20 minutes after which the current should go down. If the current is high after
one hour you have a problem.

But check the serial number first. If it is below the number abvove there is
nothing to do but order a new ABC controller.
 
As mentioned previously.

On early CL's with serial numbers < 004585 the ABC controller has the bug that causes it to malfunction and NOT
go into sleep mode properly if the vehicle is not "gotten-out-of-and-locked-within-60 seconds"

Disconnecting a battery connection and then inserting an Ampere meter is not a recommended way
to hunt for this as some other control units will not be properly awoken and synchronized in the
power-up/down/up sequencing. One thing to know is that this platform (also S-class 220) never got
stable in terms of software. It does not take much for a Xentry to write a novel of error codes
of which many are non-essential and can be disregarded. Mercedes themselfes decided
to make many of them "transient" that is, if the engine is turned off and later restarted
the DTC is cleared. A check-engine message can go away for instance. But not DTC's
set by the SRS...

The recommended way to check battery drainage is to purchase a clamp-on Ampere meter
that can read down to milliamperes. Then, after a drive, open the boot, click the lock
on the lid (fooling the system that the boot is down and in position). lock the rest
of the car and attach the clamp-on meter to one of the battery connecting cables.

Then, fetch a mug of coffee and look for the readings to drop as system after system
shuts down. You will be watching some quite high currents at first that stays on for
10-20 minutes after which the current should go down. If the current is high after
one hour you have a problem.

But check the serial number first. If it is below the number abvove there is
nothing to do but order a new ABC controller.
Thank you. I’ll be grabbing a coffee and a big coat I think, my car doesn’t fit in the garage. It sounds a much more sensible method compared to pulling fuses. I have enough electrical gremlins as it is, and don’t want to cause any more unnecessarily by doing so. If (more like when) your method shows there’s a problem, would recording times and current drops be any use is helping diagnose the problem? Do different parts of the system shut down at different times for example? I’ve been told that most of the electrical equipment within the car remains operational for an hour after turning the engine off, including the heating. With my car behaving as it is, this is something I have yet to try for myself. I live on a main road, so the only thing I’ve done so far is a visual/audible check late at night when there’s no road traffic. I ran the car the car, then locked it within 60 seconds. Then waited by the car for around an hour looking to see if anything illuminated, and listening for any noise from pumps or motors etc. A simple approach I know and proved nothing more than just how cold it gets late at night. A more technical approach is definitely needed, thank you again for the great advice.
 
Thank you, I fully charged the battery over the bank holiday. When I checked the voltage across it this evening, it had dropped by 0.5V so I think there is a drain somewhere. The big relief is that I’ve got it running and the central locking working for now. I need to address a water leak before any more electrical work. I’m pretty sure that having to charge your battery twice a week is not normal. But I figured I can use a multimeter to find the battery drain, pulling one fuse at a time. Or is this the point where someone says that’s a bad idea?
I’ve also invested in a solar charger with battery optimiser that connects directly onto the battery. Does anyone have any experience of using one of these?
when you charged the battery, was it out of the car or disconnected or still connected to the car?
What were the volts in the battery after charging, and then after resting(not connected to anything) for at least two hours?
I ask because it is best to rule out the battery not being able to hold a charge, before connecting it to the car and then trying to diagnose a current drain, when the problem could be a dodgy battery.
There is no point looking at anything else until the battery is proved to be a good one.
Also the alarm will put a drain on the battery when connected.
 
when you charged the battery, was it out of the car or disconnected or still connected to the car?
What were the volts in the battery after charging, and then after resting(not connected to anything) for at least two hours?
I ask because it is best to rule out the battery not being able to hold a charge, before connecting it to the car and then trying to diagnose a current drain, when the problem could be a dodgy battery.
There is no point looking at anything else until the battery is proved to be a good one.
Also the alarm will put a drain on the battery when connected.
Thank you, it’s a brand new battery, bought around 6 weeks ago by the gentleman I got the car off. I know he will have traceability if it proves to be faulty.
I left the battery in the car and connected while it was charging. Fully charged it read 13.0V across the terminals with the car off, unlocked and just the boot open. 24 hours later the battery read 12.5v in the same conditions.
Before I do disconnect the battery fully, can I ask if it’s safe to leave it off for a prolonged period of time, or do I need a second battery to replace the new one while I check it. I only ask as I worry about it causing more issues. Thanks again for the good advice.
 
Thank you, it’s a brand new battery, bought around 6 weeks ago by the gentleman I got the car off. I know he will have traceability if it proves to be faulty.
I left the battery in the car and connected while it was charging. Fully charged it read 13.0V across the terminals with the car off, unlocked and just the boot open. 24 hours later the battery read 12.5v in the same conditions.
Before I do disconnect the battery fully, can I ask if it’s safe to leave it off for a prolonged period of time, or do I need a second battery to replace the new one while I check it. I only ask as I worry about it causing more issues. Thanks again for the good advice.
There is no problem removing the battery and leaving it without a battery,
I swap the battery so the electric boot, central locking and alarm will work, which I find useful.
Almost any cheapo battery will do, mine is an old one from my Fiat panda.
 
There is no problem removing the battery and leaving it without a battery,
I swap the battery so the electric boot, central locking and alarm will work, which I find useful.
Almost any cheapo battery will do, mine is an old one from my Fiat panda.
That’s really useful to know, thank you. I do have an old battery off another car. I’ll make sure that’s fully charged first before swapping them over. I was worried I’d need to have two full size batteries on rotation.
 
That’s really useful to know, thank you. I do have an old battery off another car. I’ll make sure that’s fully charged first before swapping them over. I was worried I’d need to have two full size batteries on rotation.
My old panda battery is about half the size, but still does the job and the pole positions are the same as the merc, which helps to avoid confusion.
 
My old panda battery is about half the size, but still does the job and the pole positions are the same as the merc, which helps to avoid confusion.
Do you drive the Mercedes with the panda battery in? I was only intending on using a spare to prevent any memory loss. Each time I’ve disconnected the battery, I’ve noticed that the windows need to be run up and down a few times before they work properly. It’s the same with the sunroof, first operation after a disconnect is literally an inch at a time until I’ve ‘inched’ it all the way open, then closed and held the button for a few seconds. And the audio seems to have a mind of its own, constantly opening and closing the cassette slot behind the buttons at the top when it’s switched on.
 
Do you drive the Mercedes with the panda battery in? I was only intending on using a spare to prevent any memory loss. Each time I’ve disconnected the battery, I’ve noticed that the windows need to be run up and down a few times before they work properly. It’s the same with the sunroof, first operation after a disconnect is literally an inch at a time until I’ve ‘inched’ it all the way open, then closed and held the button for a few seconds. And the audio seems to have a mind of its own, constantly opening and closing the cassette slot behind the buttons at the top when it’s switched on.
I have only use it while it has been sat on the driveway sorn for the winter, as soon as the better weather comes, I tax it and drive it,, if it gets a run of at least 30minutes once a week it doesn't need additional charging.
yes the windows, clock, memory seats etc all need reset everytime, although I think, you can get a gadget to plug in to the cig socket to power these while swapping batteries, originally designed for radio codes.
 
Thread title ammended to reflect the content of the thread.

Each day I see it on the unread list and I can never recall what this thread is about. Ha!


OP: In future, please add some basic details to the title :)
 
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I have only use it while it has been sat on the driveway sorn for the winter, as soon as the better weather comes, I tax it and drive it,, if it gets a run of at least 30minutes once a week it doesn't need additional charging.
yes the windows, clock, memory seats etc all need reset everytime, although I think, you can get a gadget to plug in to the cig socket to power these while swapping batteries, originally designed for radio codes.
Thank you, that’s good to know as I was hoping to use mine as a weekend car as a pose to a daily driver.
 
I would very much advice you to make sure that the mechanical boot lock works and that the boot can be opened by using it.
Messing with a cig plug is not the best way of charging the battery. Also if the boot does not open, the only other
way is to remove the mat under the front passenger feets in order to get access to the +12V junction that resides under
an aluminium protective plate there.

While an electrically working CL has a sleep-mode battery drain current of only mA's, it is a good idea to have a
trickle charger connected if not using the car regularly. A word of caution though: A friend was using a charger
that obviously failed in some manner. One night he woke up after hearing a "BANG" from his garage.
The cause was that the battery had exploded in the cars boot and the entire luggage compartment was
contaminated with sulphuric acid. It took him there better part of the day to clean up the mess.
 
I would very much advice you to make sure that the mechanical boot lock works and that the boot can be opened by using it.
Messing with a cig plug is not the best way of charging the battery. Also if the boot does not open, the only other
way is to remove the mat under the front passenger feets in order to get access to the +12V junction that resides under
an aluminium protective plate there.

While an electrically working CL has a sleep-mode battery drain current of only mA's, it is a good idea to have a
trickle charger connected if not using the car regularly. A word of caution though: A friend was using a charger
that obviously failed in some manner. One night he woke up after hearing a "BANG" from his garage.
The cause was that the battery had exploded in the cars boot and the entire luggage compartment was
contaminated with sulphuric acid. It took him there better part of the day to clean up the mess.
Thank you, again, great advice.
The solar charger I bought wires directly onto the battery, and supposedly has charge and drain protection. Still something I won’t be taking for granted and will keep an eye on, thank you. Scrubbing and cleaning really isn’t my strong point.
The boot lock/mechanism does seem to have a fault. Whilst it locks/unlocks, and releases with both the button on the key fob and in the door. The button on the boot itself, just to the right of the lock barrel as you look at it, does nothing. Another job on the ‘to do’ list.
As soon as I get some dry weather, I’ll fit the charger and update on its efficiency and effectiveness.
 
Apologies everyone for the delay, but it’s taken me a while to make any headway.
An update on the progress so far.
I took the battery out and ran a pulse repair cycle to de-sulphonate the water (I hope that’s correct). I then fully charged and left the battery for a week. It tested good so I could move on to the car itself.
I reconnected the battery and everything seemed to work ok, except for the loss of memory. So I switched off and decided to try a basic draw test. Upon initial locking the draw was 3.1 amps for around 10 minutes, then dropping to 1.3a where it stayed for a couple of hours.
I decided to remove the trim out of the boot to install a hard wired solar charger. Once I’d removed the drivers side panel, I noticed what I assume is some kind of power distribution point mounted high up. It is completely corroded on the main cable from the battery. Something I’m sure will contribute to the draw on the battery but feel free to correct me if I’m wrong.
Also there’s a control module possibly, I’m not sure, mounted directly above the cd changer on the passenger side. I really don’t know what it is, but I noticed that’s it’s permanently warm to the touch.
I’m going to tackle one thing at a time, and follow with the same draw test. Hopefully determining where the fault lies, or some of it at least. Then keep following wires till I find the next fault.
I appreciate all your help and patience, and also encouragement to keep going with this.
 
I had battery issues originally but I thought because I was only using my CL (215) on weekends so bought a CTEK trickle charger MXS 5.0 which I believe Mercedes actuall sell branded which soon told me my battery was the issue and causing similar issues. Great trickle charger as it also checks and boosts your battery performance. However fine then for a while but no smoke without fire, as one, the PSE pump went. Had that repaired and fitted it myself yesterday and so far, everything is perfect. Might help - but as I said, I am new too and learning so thanks for all of the brilliant advice here everyone, really appreciated.
 

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