Can someone please help me? (CL Electrical Issues)

[NigelCL]

Hello everyone, I’m having a little problem.
I have a 2000 CL500 which I’ve recently acquired. When I got it home, the central locking decided to stop working. It was working when I collected the car but decided to stop after a short journey.
Today I found two severed wires in the door and decided to repair the break to see if anything happened.
There was no change so I decided to inspect all the fuses. Painstakingly pulling them out one at a time and immediately replacing them.
The central locking still doesn’t work, but after checking the fuses, the alarm has now started to work, arming and disarming with the key fob.
However my day has gone from bad to worse as now I can’t engage the starter motor. The ignition lights up, and everything seems to work aside from the central locking and the starter.
Has anybody else ever had a problem like this? Or does anyone know how I can attempt to get the car to turn over?
Many thanks in advance, Nigel.

 

[NigelCL]

Update - I checked the voltage of the battery in the boot and noticed it was a little low. I’ve put in on a trickle charge for the next few hours but left the battery in place, still wired to the car.
The central locking is now working, sort of. The alarm switches on and off with the key every time, and the locks operate occasionally. I’ve noticed the soft close on the doors and boot are now playing up. They work most of the time, but decide every few attempts to stop, requiring the fuse to be pulled to reset the pump and then fine again (for a few more goes at least).
I would like to ask, could a low battery really be the cause of my latest problem?

 

[PhantomF4]

I can’t speak with any authority about Mercedes electrical systems, but for what it’s worth my last Landrover Discovery acted very strangely unless the battery was well topped up. The initial fix was a new battery as it failed a bench test by not holding its charge. That improved things but after a few weeks the gremlins reappeared. A faulty alternator was diagnosed, was duly replaced and all was fine afterwards.

some of the weird things we experienced were random parking sensors not working, odd warnings like ESP inoperative (always disappeared after restarting the engine?), alarm not setting and best of all, the air suspension began throwing up all kinds of warnings.

I realise that’s probably not a definitive answer, but it goes to show how voltage can be crucial in modern vehicle with sophisticated electronics. Hope this helps?

 

[bob6600]

Rule out the battery first. Ensure it's fully charged and holding it too. I'm not sure about the CL, but a few MBs of that era used a compressor and air lines for things like the central locking.

 

[V6GBJ]

Hello everyone, I’m having a little problem.
I have a 2000 CL500 which I’ve recently acquired. When I got it home, the central locking decided to stop working. It was working when I collected the car but decided to stop after a short journey.
Today I found two severed wires in the door and decided to repair the break to see if anything happened.
There was no change so I decided to inspect all the fuses. Painstakingly pulling them out one at a time and immediately replacing them.
The central locking still doesn’t work, but after checking the fuses, the alarm has now started to work, arming and disarming with the key fob.
However my day has gone from bad to worse as now I can’t engage the starter motor. The ignition lights up, and everything seems to work aside from the central locking and the starter.
Has anybody else ever had a problem like this? Or does anyone know how I can attempt to get the car to turn over?
Many thanks in advance, Nigel.

My experience is limited to R230 SLs in respect of electrics/battery but it is certainly true of R230s that if the rear battery is low, then various electrical features will shut down. I should check everything again when the battery is fully charged.

 

[NigelCL]

I can’t speak with any authority about Mercedes electrical systems, but for what it’s worth my last Landrover Discovery acted very strangely unless the battery was well topped up. The initial fix was a new battery as it failed a bench test by not holding its charge. That improved things but after a few weeks the gremlins reappeared. A faulty alternator was diagnosed, was duly replaced and all was fine afterwards.

some of the weird things we experienced were random parking sensors not working, odd warnings like ESP inoperative (always disappeared after restarting the engine?), alarm not setting and best of all, the air suspension began throwing up all kinds of warnings.

I realise that’s probably not a definitive answer, but it goes to show how voltage can be crucial in modern vehicle with sophisticated electronics. Hope this helps?

Thank you for the reply. I’m currently trawling through all the posts I can find referring to engines refusing to turn over while the charger does its job. It was working fine this morning, the battery is new but hasn’t really been run on the car yet so hopefully this will help.
When I open the car, I’ve noticed that a message appears on the dash saying something about a chip not being recognised and I’ve never seen this before. I’m wondering if it’s possible that I’ve somehow managed to for want of a better (or correct) phrase, decode the key.

 

[NigelCL]

Rule out the battery first. Ensure it's fully charged and holding it too. I'm not sure about the CL, but a few MBs of that era used a compressor and air lines for things like the central locking.

Thank you, the pse pump seems to be working fine, I can hear it charging when I reset it by pulling the fuse. It charges then stops, and only operates again if I close a door or the boot.

 

[NigelCL]

My experience is limited to R230 SLs in respect of electrics/battery but it is certainly true of R230s that if the rear battery is low, then various electrical features will shut down. I should check everything again when the battery is fully charged.

Thank you, I think you’re right. Better to let the battery fully charge before attempting any more common butchery.

 

[bob6600]

Thank you, the pse pump seems to be working fine, I can hear it charging when I reset it by pulling the fuse. It charges then stops, and only operates again if I close a door or the boot.

The low battery voltage may have caused the pump to not kick in. Mine had the passenger door pipe broken, which I fixed. If it is all the central locking and/or soft close and boot not working then keep and eye on the PSE pump.

As for the car not starting, if the battery is fine then check that the display shows the selector in 'P' or 'N'

 

[NigelCL]

The low battery voltage may have caused the pump to not kick in. Mine had the passenger door pipe broken, which I fixed. If it is all the central locking and/or soft close and boot not working then keep and eye on the PSE pump.

As for the car not starting, if the battery is fine then check that the display shows the selector in 'P' or 'N'

Thank you, I will. I’m going to leave it on charge over night, refresh my own batteries too, and have another go in the morning.
I did spot a little bit of water in boot, right above the pse pump. So I’m going to strip out the boot carpet and tr trim to expose the pump and check for damp and corrosion. Then time to hit it with the talcum powder.

 

[Justintyme]

As far as I know, your car should have the OBD socket for reading faults,,,,,,,if it has , then it should be the first step to do a scan, especially for electric gremlins..if you know anyone who has iCarsoft or similar scanner?

 

[NigelCL]

As far as I know, your car should have the OBD socket for reading faults,,,,,,,if it has , then it should be the first step to do a scan, especially for electric gremlins..if you know anyone who has iCarsoft or similar scanner?

Thank you, yes I have a friend who has a basic code scanner which I’ve no doubt, I shall be borrowing very soon - repeatedly.
If I can get it started, I intend to take it to a Mercedes specialist and get plugged into M-star for a proper diagnosis.
A labour of love I can deal with, a bottomless pit I can’t I’m afraid.

 

[Justintyme]

Thank you, yes I have a friend who has a basic code scanner which I’ve no doubt, I shall be borrowing very soon - repeatedly.
If I can get it started, I intend to take it to a Mercedes specialist and get plugged into M-star for a proper diagnosis.
A labour of love I can deal with, a bottomless pit I can’t I’m afraid.

Once upon a time ( where have you heard that before??? ) cars were much simpler ( if not as reliable or "Green" ) and easier to fix, relatively speaking. But now? Being a mechanic now entails also having a knowledge of electronic's and computer's that would be the envy of an IT professional... and it's going to get worse, IMHO. So its a good idea when you have a problem with your car, to have it scanned as a first step. Good Luck solving your problem.

 

[NigelCL]

Once upon a time ( where have you heard that before??? ) cars were much simpler ( if not as reliable or "Green" ) and easier to fix, relatively speaking. But now? Being a mechanic now entails also having a knowledge of electronic's and computer's that would be the envy of an IT professional... and it's going to get worse, IMHO. So its a good idea when you have a problem with your car, to have it scanned as a first step. Good Luck solving your problem.

Thank you, and I couldn’t agree with you more. I’m just a humble engineer, not a computer scientist. I really don’t not have much faith in electric or hybrid vehicles yet. And my personal opinion is that it’s ‘greener’ to keep older cars on the road than to produce new ones. He says restoring a fuel guzzling V8.

 

[Uky]

Congratulations to the CL500! It is the closest thing to a battleship on the roads. The very definition
of comfort and luxury. And it still looks great, 20 years after its introduction.

But it is an everlasting "project". There is always something to fix.

The CL (215) has an air compressor located behind the panneling in the boot on the upper left side (at least on a LHD vehicle).
This pump supplies air to both the central locks and the seat variable support (controlled by the rotary switches underneath
the knees when sitting), If there is a leak, there is most likely air left in the system to unlock or lock the doors once.
After starting the vehicle, a "thump-thump-thump (etc)" should be heard for a short amount of time as the pressure
is built up. If there is a leak (mine was in the Y-junction UNDER the mats) there will be a time-out in order to protect
the pump. The hoses are white and stiff and runs under the seats in under the floor mats. If the Y-junction is cracked
both seats will have to come out. And they are HEAVY. Two persons are required...

If a CL suffers a Battery dip, all sorts of things can happen. Window calibrations will be gone. There will be a "novel"
of error messages. The Audio Power amp will not turn on together with the Comand but the most freightening is
that the steering wheel sensor will loose its calibration. A Red warning message will appear in the Instrument Cluster
"ABS/ESP/BAS failure Visit Workshop" (or something similar). Driving the CL slowly and turning the steering wheel
max left, max right and max left again will clear this error message.

On early CL's there is a hardware bug in the ABC-controller. If the vehicle is not locked within 60 seconds
of stopping, getting out the ABC-unit will not go into sleep mode. It will consume some 360 mA until
the battery is drained. The ONLY way to fix this is to replace the module after which the car has to be
recalibrated on a level floor/street/workshop using Star/Xentry.

When the CL has done > 100,000 km, it is likely that a pulsation damper for the ABC-system is worn out.
This can be heard inside the passenger compartmenat, a "roar" that goes away above 1800 RPMs
when at standstill and Neutral. This damper must be replaced and it is not that expenceive.

Furthermore, Changing the oil and filter in the ABC system is not included in any service plan.
But it is an ABSOLUTE MUST as the oil rots with time and goes from transparent green to
sluggish gray and smells bad. Neglegence to do this can result in compressor failure.
The compressor is a coaxial type and the two sections are used for the steering
and the ABC system as well. It is "a bit expenceive".

What else needs to be assessed is the cable harness between the car body and the doors.
The loudspeakers, the SRS and door controller wires runs in a "less than optimum way"
and it is likely that some wire will brake in time. I managed to fix that myself with a bit
of carful planning and patience. Just be aware that there is an AirBag in the door...

 

[NigelCL]

Congratulations to the CL500! It is the closest thing to a battleship on the roads. The very definition
of comfort and luxury. And it still looks great, 20 years after its introduction.

But it is an everlasting "project". There is always something to fix.

The CL (215) has an air compressor located behind the panneling in the boot on the upper left side (at least on a LHD vehicle).
This pump supplies air to both the central locks and the seat variable support (controlled by the rotary switches underneath
the knees when sitting), If there is a leak, there is most likely air left in the system to unlock or lock the doors once.
After starting the vehicle, a "thump-thump-thump (etc)" should be heard for a short amount of time as the pressure
is built up. If there is a leak (mine was in the Y-junction UNDER the mats) there will be a time-out in order to protect
the pump. The hoses are white and stiff and runs under the seats in under the floor mats. If the Y-junction is cracked
both seats will have to come out. And they are HEAVY. Two persons are required...

If a CL suffers a Battery dip, all sorts of things can happen. Window calibrations will be gone. There will be a "novel"
of error messages. The Audio Power amp will not turn on together with the Comand but the most freightening is
that the steering wheel sensor will loose its calibration. A Red warning message will appear in the Instrument Cluster
"ABS/ESP/BAS failure Visit Workshop" (or something similar). Driving the CL slowly and turning the steering wheel
max left, max right and max left again will clear this error message.

On early CL's there is a hardware bug in the ABC-controller. If the vehicle is not locked within 60 seconds
of stopping, getting out the ABC-unit will not go into sleep mode. It will consume some 360 mA until
the battery is drained. The ONLY way to fix this is to replace the module after which the car has to be
recalibrated on a level floor/street/workshop using Star/Xentry.

When the CL has done > 100,000 km, it is likely that a pulsation damper for the ABC-system is worn out.
This can be heard inside the passenger compartmenat, a "roar" that goes away above 1800 RPMs
when at standstill and Neutral. This damper must be replaced and it is not that expenceive.

Furthermore, Changing the oil and filter in the ABC system is not included in any service plan.
But it is an ABSOLUTE MUST as the oil rots with time and goes from transparent green to
sluggish gray and smells bad. Neglegence to do this can result in compressor failure.
The compressor is a coaxial type and the two sections are used for the steering
and the ABC system as well. It is "a bit expenceive".

What else needs to be assessed is the cable harness between the car body and the doors.
The loudspeakers, the SRS and door controller wires runs in a "less than optimum way"
and it is likely that some wire will brake in time. I managed to fix that myself with a bit
of carful planning and patience. Just be aware that there is an AirBag in the door...

Thank you, you’ve given me so much helpful information to go at and I’m very grateful.
I got home and I unhooked the battery charger. Closed the boot and tried the key, and - tadaa- it unlocked. Key in ignition and it started first time. You were right about the error messages, it came up with 3, only one of which I was aware of. Turning the steering wheel from lock to lock slowly cleared two of the three, leaving just the ABC error which I knew about. Thank you, I really mean THANK YOU!!!
The ABC system had a new dual pump fitted three years ago by a Mercedes dealership. It also had a full fluid flush and change at the same time. Sadly though, that’s when the car got parked up. We fitted a new battery and managed to get it home. This is also my first Mercedes, so I’m just learning about all the idiosyncrasies and failsafes built into the car.
I didn’t give a thought to the airbag in the door either while blissfully reconnecting and soldering away, thankfully nothing happened. I’m now unsure however, whether it the repair to the wiring, or just fully charging the battery that cured my problem.
As much as it’s a tick against the first little job to do, it. Is definitely going to be the first of many!! I did try running through a cycle of opening, starting, stopping and locking the car, and on a couple of occasions didn’t start. All the ignition lights came on, everything electrical seemed to work, but turn the key and absolutely nothing happened. A job for the near future I’ve no doubt.
If this can be of any help to anyone else going through similar problems, I’d have to say lesson one is check the condition and output of your battery first.
Thank you again for all the great advice, hopefully I can contribute to solutions as I go and people can learn from my mistakes.

 

[Uky]

And a couple of things that I forgot to mention:

Never Ever!...Disconnect any of the SRS-components while the ignition key
is in state 1 or 2. You *will* set a DTC - Trouble code that can only be reset using a diagnostic tool. I think that such a tool
is a must-have today when maintaining an older MB. Always remove the keys well outside any Keyless range or better still:
Disconnect the battery if doing any electrical maintenance.

If a light bulb goes bad, the controller will shut down that signal path. Replacing the bulb will not turn on the new one again.
It is during ignition on that a new check is performed. The CL is also sensitive for light bulb unsymmetry. Always replace both
left and right side bulbs with new ones purchased out of the same package. The sockets for the 6W Halogen pilot lamps
used in the middle front headlamps will most likely have to be replaced. Mine was severly burned. Not sure if they can
be purchased as a separate spare part. Perhaps seach eBay...

The M113 V8 is rock solid as long as it is serviced regularly. Be careful when replacing the spark plugs. Attach them to a rubber hose
and gently screw them in place using only your hands/fingers. The threads are easily destroyed. The spark plugs closest to the
passenger compartment are the tricky ones. Once you feel that the plugs are correctly inserted, a wrench can be used for fastening.

With time, the bearings in the belt (water pump, servo pump, generator, will wear out but they are quite easily replaced.
You will hear a grinding sound from the front of the engine.

The instrument cluster illumination is using a small U-shaped fluorescent lamp powered by a built-in switching
power supply. I never had any problem with it but rumors are that they do sometimes fail.

When I put mine away for winter storage, I purchased a batch of wooden poles cut to short lengths. I think they
were 9 x 9 cm. Drove the car into the garage and elevated it using the ABC-system. Then slided the wood parts
in to where the lift protrusions are located (rubber distances) and then lowered the car. The tyres then sat
without any weight on them. The ABC system can leak which will result in the car lowering itself with time.
There is a limit specified for this so it is not unknown, BUT the car must not be allowed to sink to low as it
according to Mercedes cannot lift itself up again. If you plan to put it in winter storage, then think about this.

Another thing to do is to remove the side skirts and bottom panneling and look for corrosion.
This is unfortunately not uncommon. At least not in Scandinavia. With time, a lot of dirt gathers
in the side skirts and the screws/nuts that keeps the bottom panneling are also subject to this.
I took mine apart, managed to stop the corrosion and also carefully inspected the tubes and
hoses used for fuel, ABC, brakes etc. These are made of steel - not copper and they are subject to
corroision as well. Also pay attention to the ABC valves.

The 3rd brake light is also a matter of concern as the gasket that shall prevent water ingress
will wither and crack. Water will then get in, find its way to the number plate illumination and
corrode the connector terminals. It will also find its way to the mechanical lock, manufactured by "Huf"
that consists of a mixture of different metals. Since no-one ever uses this lock, it is almost always
heavily corroded. It can be repaired by carefully taking it apart, cleaning the parts and then put them
together again. Just remember the exakt location of the lock elements!

 

[NigelCL]

And a couple of things that I forgot to mention:

Never Ever!...Disconnect any of the SRS-components while the ignition key
is in state 1 or 2. You *will* set a DTC - Trouble code that can only be reset using a diagnostic tool. I think that such a tool
is a must-have today when maintaining an older MB. Always remove the keys well outside any Keyless range or better still:
Disconnect the battery if doing any electrical maintenance.

If a light bulb goes bad, the controller will shut down that signal path. Replacing the bulb will not turn on the new one again.
It is during ignition on that a new check is performed. The CL is also sensitive for light bulb unsymmetry. Always replace both
left and right side bulbs with new ones purchased out of the same package. The sockets for the 6W Halogen pilot lamps
used in the middle front headlamps will most likely have to be replaced. Mine was severly burned. Not sure if they can
be purchased as a separate spare part. Perhaps seach eBay...

The M113 V8 is rock solid as long as it is serviced regularly. Be careful when replacing the spark plugs. Attach them to a rubber hose
and gently screw them in place using only your hands/fingers. The threads are easily destroyed. The spark plugs closest to the
passenger compartment are the tricky ones. Once you feel that the plugs are correctly inserted, a wrench can be used for fastening.

With time, the bearings in the belt (water pump, servo pump, generator, will wear out but they are quite easily replaced.
You will hear a grinding sound from the front of the engine.

The instrument cluster illumination is using a small U-shaped fluorescent lamp powered by a built-in switching
power supply. I never had any problem with it but rumors are that they do sometimes fail.

When I put mine away for winter storage, I purchased a batch of wooden poles cut to short lengths. I think they
were 9 x 9 cm. Drove the car into the garage and elevated it using the ABC-system. Then slided the wood parts
in to where the lift protrusions are located (rubber distances) and then lowered the car. The tyres then sat
without any weight on them. The ABC system can leak which will result in the car lowering itself with time.
There is a limit specified for this so it is not unknown, BUT the car must not be allowed to sink to low as it
according to Mercedes cannot lift itself up again. If you plan to put it in winter storage, then think about this.

Another thing to do is to remove the side skirts and bottom panneling and look for corrosion.
This is unfortunately not uncommon. At least not in Scandinavia. With time, a lot of dirt gathers
in the side skirts and the screws/nuts that keeps the bottom panneling are also subject to this.
I took mine apart, managed to stop the corrosion and also carefully inspected the tubes and
hoses used for fuel, ABC, brakes etc. These are made of steel - not copper and they are subject to
corroision as well. Also pay attention to the ABC valves.

The 3rd brake light is also a matter of concern as the gasket that shall prevent water ingress
will wither and crack. Water will then get in, find its way to the number plate illumination and
corrode the connector terminals. It will also find its way to the mechanical lock, manufactured by "Huf"
that consists of a mixture of different metals. Since no-one ever uses this lock, it is almost always
heavily corroded. It can be repaired by carefully taking it apart, cleaning the parts and then put them
together again. Just remember the exakt location of the lock elements!

Some more excellent points and guidance, thank you so much.
Having had to remove the wheels today, I discovered said dirt build up behind the side skirts, and yes, signs of the dreaded corrosion too. It doesn’t look that bad yet so it’s probably a good time to clean it all out properly. Hopefully stop it getting much worse, and a perfect opportunity to inspect all the lines you mentioned. It has been stood after all.
Winter storage is not an option either. I do have a garage, but, not surprisingly, the car is too long. Plus, I’m basically giving myself 12 months to try and get it to a keepable condition. Although I am beginning to doubt myself a little, especially when it comes to the ABC system. Before I got it home, I cockily thought to myself, yes, I can change a couple of shock absorbers, replace some seals and ‘o’ rings and I’m good to go. Right now I’m working out a budget to have it done by a professional instead. That being said, you have further inspired me to try to do all I can first of all. By the sound of things, if i can get mine half as good as yours, I’ll be a very happy man indeed.

 

[Jockcl500]

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.

 

[NigelCL]

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.

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?