CL500 electrical problems - Lumbars + rear windows

[Will Barber]

Hello all.

After just picking up my 2005 CL500, I have two small electrically related problems with it... the first one really is quite confusing.

1. The rear electric window switches (in the rear cabin) do not light up or work the rear windows. The rear windows can be controlled with the drivers switches and I've tried sliding the isolation switch in both directions but to no avail. ALL fuses check out okay.
2. Both the driver and passenger seat lumbar supports are non operational. These are heated/cooling seats without massage function. Again ALL fuses check out okay. I've taken out both lumbar control switches to check and they're okay. I wouldn't have thought that the vacuum hoses on BOTH seats have failed, besides they look very pliable and intact. Obviously they are 100% pneumatic as there are no wires going to the switch, the 'thumbwheel' switches are simply valves.

Thank you for your time, very appreciated.

Kind regards, Will

 

[BlackC55]

I expect the window fault is a faulty rear control module.

A check with a star is what is needed

 

[spike60]

When I changed the vacuum central locking pump on my CLK for a 2nd hand one I lost the lumbar functions on the seats despite the part numbers being the same. I suspect mine needs enabling with a Star scanner but perhaps yours has a fault on the electronic control side of the pump gong to the seats.

 

[Benza750]

As above

If the pump has been changed at some point & not been set up properly on Star for that model & it's configuration they won't work.
I'd get that checked first

 

[Will Barber]

Cheers guys, will get it plumbed into STAR then.
Typically, how much should I be looking at paying a dealer to do this.
I know exactly what's involved as I use VAS and ODIS on Bentley cars all day for fault finding/clearing and set-up.
Will

 

[Dash1]

Hello all.

After just picking up my 2005 CL500, I have two small electrically related problems with it... the first one really is quite confusing.

1. The rear electric window switches (in the rear cabin) do not light up or work the rear windows. The rear windows can be controlled with the drivers switches and I've tried sliding the isolation switch in both directions but to no avail. ALL fuses check out okay.
2. Both the driver and passenger seat lumbar supports are non operational. These are heated/cooling seats without massage function. Again ALL fuses check out okay. I've taken out both lumbar control switches to check and they're okay. I wouldn't have thought that the vacuum hoses on BOTH seats have failed, besides they look very pliable and intact. Obviously they are 100% pneumatic as there are no wires going to the switch, the 'thumbwheel' switches are simply valves.

Thank you for your time, very appreciated.

Kind regards, Will

Hi Will Barber,

Firstly - Welcome to the forum and congratulations on your new ownership of a W215. Depending upon your own vehicle specification, the CL is one of the most complex MB’s ever built from an electrical architecture point of view, and certainly one of the most expensive, problematic and troublesome if they do go wrong. I do speak from personal experience here, because I actually own one and have done so for the past 8 years or so now. What a fabulous car to own and drive though even with its problems, so a further welcome to the W215 club.

Secondly - I see from your initial post that you are a Technical Author for Bentley Motors, so with this in mind, you should have no trouble whatsoever in navigating around the electrical system. Given that you have two separate unrelated issues, (rear window switches inoperative and PSE lumbar pump) we’ll look at these individually. I’ll post both solutions on here to save posting again later. I presume you have a fuse chart to hand in the event that we may need it later on. Also, and this is particularly important in diagnosing your issues correctly, you say that all of the windows work from the drivers door/window switchpack, with the exception of the rear window “isolation” switch, also, the rear windows don’t work from their respective rear switches, is this still correct? If so, then we can now rule out and assume that all the relays and motors are working properly, otherwise, they wouldn’t work from the front door/window switchpack. You also stated that the rear window switches don’t illuminate, is this still the case?

For reference purposes, the doors and rear window switches do not illuminate unless you turn on the sidelights, with the lights switched off, there is no way of actually knowing from a visual point of view if any of these switches are active/inactive, so this may not initially be representative as a fault. Please check that the rear window switches illuminate with your sidelights on to confirm a power supply is available to these switches before we go any further, if they don’t come on when the sidelights are on, then the plug to the rear window switches is probably disconnected for some reason, probably someone has had the centre console out at some time and forgot to plug them back in. One light out could possibly represent a problem, but both lights out is highly unlikely to be a problem and is generally a plug disconnection related issue. Similar issues will occur with both the rear windows being inoperative at the same time as they form part of the same multi-plug connector and the integral wiring loom under the centre console and they are “hard wired” back to the rear SAM module.

BTW, as a technical person yourself, you may also be interested to know and should also note that some of these window functionalities are directly on the CAN bus communication network. Individual windows operated from their own respective sides communicate through their own door/window control modules or the rear SAM control module and the driver’s door switchpack communicates through its own door/window module with all the door/window module on the CAN bus. I’ll not post any data regarding CAN bus voltages for the very reason you don’t have an issue with it as far as I’m concerned, everything works from the door switchpack so the systems integrity has continuity. You would need to see the topology of the electrical architecture to evaluate the integration of the network system anyway. FYI, and future reference, below is a typical description of the protocol for the MB CAN network on the CL - W215

CAN C - Engine CAN (also known as the chassis CAN) Fast communication speeds 125 kbps or 500 kbps
CAN B - Interior CAN (also known as the body CAN) Communication speed 83 kbps Information from CAN C can be sent to the control modules on the CAN B or vice versa via the Electronic Ignition Switch (EIS). The EIS is the only control module that can transfer the messages and is known as the gateway.

I’ll simplify it in a logical order, print it off and keep it with you when you do the checks on the car. Check all of the following fuses first, as all of these fuses listed below are related within the window systems operation. Note that Fuse No. 13 is representative on all the windows system functionalities and individual fuses form part of that sub-system.

Power window, drivers side - F13 - (40amp) Colour - Amber - Engine bay compartment - left
Power window, passenger’s side - F13 - F39 - (40amp) Colour - Amber - Engine bay compartment - right
Power window, rear left - F13 - F72 - (40amp) Colour - Amber - Under the rear seat on the right
Power window, rear right - F13 - F74 Colour - Amber - Under the rear seat on the right

If these are all OK, then we can carry on, by the way, the relays for the rear window system are actually located under the rear seats and separate from the rear fusebox and are controlled solely by the rear SAM (signal acquisition module). You don’t need any sophisticated equipment at the moment to test and/or evaluate this system, and anyone such as yourself that is technically minded with the ability to use a multimeter and/or preferably a logic probe can diagnose all of these input/output trigger signals to determine where the fault actually lies, if indeed it is a fault. However, if you do find that it requires a new SAM, which I very much doubt anyway given what you have already said is functioning, then it would have to be configured to the car with MB’s STAR equipment, similar to your VAS system.

The particular rear window issue that you describe is similar if not the same as a common failure scenario on these cars anyway and results from either a faulty rear window “isolation” switch on the drivers door/window switchpack – which is a simple input trigger to the drivers door/window module and sent to the rear SAM over CAN, a faulty drivers door/window module not communicating over CAN or a rear SAM input/output signal failure. If the SAM doesn’t receive a signal input, then it can’t give a command output, it’s that simple. But I repeat, I don’t think you have an issue at all here with the communication network, because all the other functionalities are operative.

Anyway, if you wish to proceed, remove the switchpack first on the drivers door and bridge (from the rear of the connector block only) the isolation switch circuit, (bell these out first to determine which they are, but disconnect it from the door/window module before you do this anyway) if the system is now OK, replace the switchpack, if not, then the input signal to the rear SAM may be compromised by one of the above mentioned faults. The rear SAM will not switch and/or activate the rear window relay coil to ground if it doesn’t receive its input signal - check these input/output signals with your logic probe to confirm activation. Take your time and follow the wire colour coding to determine the output wire to the window relay coil, by the way, the relay coil actually consumes 0.174 amps or 174 milliamps through pins 85 and 86 if functioning correctly. The rear SAM is also located under the rear seat and forms part of the fusebox, but it does separate from the fusebox for easy access. Caution - I shouldn’t need to tell you this anyway, but never ever disconnect a module plug with the ignition in the “on” position.

Also, there is a n/side and o/side window “dropdown/closure” feature on the CL model vehicles when opening/closing the doors to enable the windows to seat and seal securely under the weather seal when the doors are closed. To operate this feature, then press the door-operated switch all the way in, they are located near the door lock striker plates. Try them both please to confirm operation. If the windows now go up/down very slightly (approx 10 mm) when you press/release the door switches, then the above fault you described indicates once again that it’s the door/window switchpack, rear SAM, or that the plug connector under the console is disconnected from the window switches. These door switches are in fact a direct input trigger signal received by the rear SAM and the output command is a ground circuit to the window relay coil through pins 85 and 86, which in turn powers the window motors through pins 30 and 87 of the relay. If these are both working, which we already know that they are, then it’s definitely not relay related and you can rule these out once again.

PSE - Pneumatic Service Equipment

Your post also indicates that you have a possible issue with the lumbar control in both the seats and that it appears to be inoperative. I’ll take you through the process and give you some valuable info on how to check and test the systems functionality. The PSE pump on the CL is actually located in the boot and it’s on the n/side quarter behind the boot panelling in a padded black plastic case. When you remove the cover, the two left hand connections (FoL and FoR) on the lower section of the grey manifold are not used at all on the CL coupe, they are only used on the 4 door saloon versions, such as the “S” class - W220 models for the rear door locks. However, yours will appear to be exactly the same and the following will help you to identify the destinations from the pump manifold – onwards.

I’ve added a photo at the end of this post of the PSE pump off my own CL for easy identification and reference, click on the photo and zoom in for clarification of the lettering abbreviations. Note: the vacuum connections and their respective destinations from the pump manifold – onwards.

KAF - Rear Head Restraints - White Line with Grey Connector.
HECK - Boot Lid - Yellow Line with Grey Connector.
TD - Fuel Flap - Yellow Line with Grey Connector.
MKL - N/S and O/S Seats - Grey Line with Grey Connector - this is the one that you want to check.
FT - O/S Front Door - Yellow line with grey connector.
BFT - N/S Front Door - Yellow line with grey connector.
FoL - N/S Rear Door - None connected on my CL - 4 door versions only.
FoR - O/S Rear Door - None connected on my CL - 4 door versions only.
SK - N/S and O/S Boot Security Locks - optionally fitted security equipment - fitted on my CL

These locations and identifications will always come in very handy if you ever need to carry out any “vacuum/pressure” leak-off tests later. Sometimes, a very simple vacuum/pressure leak can in fact cause the pump to run on much longer than necessary, and in the process, draw excess current which in turn will give rise to the fuse blowing, rendering all the PSE system inoperative – the car will not “globally” lock although the alarm system is armed. The“normal” current consumption (measured in series in place of fuse 62 with a good quality ammeter) from these pumps should not exceed 15 amps and fall within in the range of between 10amps - 14amps, and the system should be protected with a 20-amp fuse - (yellow) - fuse number 62 is in the rear fuse box under the right hand side seat.

The issue that you refer to appears to be one on one vacuum/pressure circuit only, and the two simple checks/tests, which I will list below, will indeed confirm this. Firstly, has this pump ever been changed to your knowledge, if so, then it may have never been properly configured to the vehicle, (this is not generally a plug-and-play module and forms part of the overall vehicles “global” security operated through the CAN bus network) if it has been configured, and it does appears to look that way from my point of view, then it’s quite probable that there is a leak in the vacuum/pressure pipe or that the pump output - MKL on the grey manifold port to the seat system is faulty or leaking, if its the latter, then you are going to need a replacement pump. You can check and confirm this quite easily though if you have a vacuum/pressure gauge, attach the gauge to the MKL port outlet on the pump and activate the lumber support system and note the reading. If it’s not working at all, or losing any pressure, then you may need to replace the pump.

To check the MKL vacuum/pressure line to the seats, attach a hand operated vacuum/pressure gauge, such as a (mityvac or similar) to the pipe and activate it, or, if you haven’t got a vacuum/pressure gauge, just suck or blow down the pipe, it should hold vacuum or pressure, if not, then a leak is evident and you will need to trace it back through to the seats. Alternatively, an even simpler or cruder test in the absence of any tools at all, would be to attach and secure an over-inflated simple balloon to the MKL pipe connector and if the balloon deflates, then there is an obvious leak in the seat system. If you listen very carefully as you work on the seats etc, you will hear it hissing. If you do need a diagram of the vacuum system and its connection points, then I can upload one for you, just let me know.

The part number if you do unfortunately require a pump is - MA 220 800 12 48. This is the revised pump number as the earlier one has a different part number and employed the use of a different motor. This is the one that you may need if you do decide to replace it. The cost of the pump from MB was £428.00 plus vat, although this is the price indicated on my invoice, which is dated 09/01/2009. It may and probably has increased in price since this date – check current prices with MB. This is my third pump by the way in just over 8 years now - notorious for failure – a really cheap and under-engineered unit. Even the one fitted at the above date was replaced under warranty after only16 month’s use, and even this one has had some problems of late, which I have now rectified and modified. Don’t tamper with it if you are not confident and electrically minded though, as you will certainly do more damage that good.

Generally speaking, these units are non-repairable items with the exception of the pump motor. You could very well remove the pump and dismantle it and check the circuit board for any dry soldered joints and the like, but they do fail on the solenoid/switching valves, and these are non-repairable/replaceable items. You will need to check the vacuum/pressure output at the respective MKL manifold port though to confirm this anyway. As a technical person yourself, whilst you are doing the above tests, then why not do all the tests at the same time and monitor all the outputs from every port for data reference in the event of any future problems, that way you can compare the data and evaluate as to whether or not its diminished in vacuum/pressure over time as the pump ages.

It’s a really complex car as I have already said, and I have tried to keep this post as brief and simple as is possible without going in to every single wiring pin-out test, given your own technical skills though, try all the above checks and then come back to me. I’m not convinced given your symptoms that either the SAM or the PSE units are at fault here. Before you do anything though, move the rear window isolation switch from left to right quite quickly and vigorously, as these switches are really cheap and inferior quality and the contacts soon fail. Also, don’t forget to check the lights on the rear window switches to confirm illumination and a voltage supply when you operate the light switch, as it could just very well be the plug is simply disconnected under the centre console. My apologies for the lengthy post, but I have actually cut this really short and tried to explain it as simply and as quickly as is possible, hope it helps anyway.


Best Regards and a Happy New Year.


Dash1

 

[Will Barber]

Dash 1
Thank you very very much indeed.... a very thorough explanation and very much appreciated.
I will take on board all discussed and will report back with my findings.
Once again, my sincere thanks.
Will

 

[bkubus]

New PSE pump

Hi to all.
Hi guys I do not understand that about new PSE pump. Just today got a brand new pump for my s class W220 3,2 CDI 2002 reg. from MB shop and it wont work on lumbar support. It does on everything else but that particular one it is not, does it mean that i have to go back to MB and it needs to be set up or how it does work. Any response will be more than appreciated