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Discussion Starter · #1 ·
hi, I have a v220 which has been suffering suspension problems.

The symptoms are different to those I have seen from others on the forum, in that the dashboard light does not come on at all - not even when the key is turned to start the vehicle!

I have removed the compressor, and been able to connect it across the battery to get it to work. (This is actually quite easy given it's location, & I can at least pump up the bellows if needed. It is a pain at the moment, as I need to crawl under the car, which usually means raising it, becase it is so low at the rear).

All the fuses appear intact, and I have access to the control module. Is the lack of panel indicator also an indication of control module failure? Could it be something else? (I have already had the dashboard module with the speedo in replaced once).

Any pointers helpful. THanks.
 

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v230 ambernite 1997
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You could try the easy bits first, do a Continuity check on the system in particular the wires under the car which are subject to road crap, clean all contacts up etc
 

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I t sounds like you might have two problems....firstly it sounds like the dashboard light has broken. Secondly, since the suspension is not working you could have a problem with the solenoid valves that allow air to flow in and out of the air bags. Have you checked that the valves switch when 12V is applied directly to them. Wheb you power the pump directly how do you control which side the air goes to?
Greetings,
Christof
 

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Discussion Starter · #4 ·
thanks guys.

I have removed the control module from behind the rear panel, and if I connect pins 9 (KOMP = compressor) and 15 (KL31 = ground/0v) the compressor works. The KOMP pin controls the relay, so I know that all the circuitry from the relay works fine. The solenoids are both open by default, so both sides pump up when I do this.

I'm tempted to get some flat bladed connectors and a switch, and leave the system as it is. The switch will be accessible in the access area where the jack is stored. I could even extend it to operate the solenoids manually (pins 1 & 2 QSVL&R).

I've got money on the control module being up the spout, but I'll need to take it in for connection to an analyzer to confirm.

I'm also considering removing the compressor again to give it a good coat of hammerite. That way it may last a little longer. It's in a really stupid position getting all the muck off the road on to it, causing it to corrode quickly.
 

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Hum, sounds like you have some interesting information. Where is the rear panel behind which the control module sits? I have thought about adding a switch to allow the suspension to be raised and lowered manually. But, I don't know what happens if the suspension is accidentally pumped up too high.
I thought the solenoids were meant to be closed by default so that the sides could be pressurized independently.
Have you looked at:
http://v-klasse-presser.de/shop/Scripts/default.asp
They have a very nice looking solution for protecting the pump.
 

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Discussion Starter · #6 ·
the control module is on the right hand side as you open the tailgate. Simply undo all the screws you can see up to the central pillar. The lining is clipped near the window, and requires a bit of force to remove - simply pull towards you. The module is directly above the access panel to the jack, and is held in place by a mounting plate. Once removed simply unplug the connector. Mine is marked with the connection pin numbers and abreviations.

The connector on the main wire loom is female, so should take spade connectors. I simply use a piece of wire at the moment, although I noticed today that the left hand side is lower than the right, so I need to work out how to control the solenoids for raising one side only.
 

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Does anyone have experience of changing the Air Suspension system for a standard Coil spring system ............. does a replacement system exist.

I'm currently having Air Suspension troubles and I'm looking for a conversion to try to advoid all the problems and costs !

TimH
 

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Discussion Starter · #8 ·
actually as systems go, the air suspension is straightforward. There are sensors on the wheels (not sure where) that feed to the control module. The compressor is driven via a relay that feeds air to the left & right side bellows through solenoid controlled valves.

All the components are easy to access - certainly the compressor, valves relay & control module. The bellows may be a different matter. With this in mind, any repairs shouldn't be too expensive, but for some reason the components cost an arm & a leg. The compressor can be removed in a couple of minutes by reaching under the car!!

So, to me, the problem is that the compressor is in a stupid position in that it collects all the muck from the road when the vehicle is moving. If it weren't for that, I think the reliability of the system would be a lot higher.
 

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TimH said:
Does anyone have experience of changing the Air Suspension system for a standard Coil spring system ............. does a replacement system exist.

I'm currently having Air Suspension troubles and I'm looking for a conversion to try to advoid all the problems and costs !

TimH
I have been told their is a problem with this air suspension since day 1. I have been told that people became sick of problem and changed over to shocksers and springs. I have been to Mercedes dealership today and they confirmed the problems and told me it would be £650 to convert and that I could convert, but they never told me this until I asked them. At £37+an hour for fault finding who would tell you that you could convert. I have been on to Mercedes head office and they are making enquires to ascertain if this is indeed a major problem. Basically if this is a problem why should I keep paying for a design fault even though my vehicle is a 1998.
 

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Sheils,

You speak sense !! I agree. I have been talking to the MB Dealers in Ireland and I have failed to get a straight answer. They charge £80/Hr for talking bull**** !

Last night I got under the V220 and a Vito van for a look and it all looks very feasible.

I suspect that £650 if expensive. I believe that the parts needed are 2 springs 2 shocks, 4 shim plates, spacers, bolts, nuts &screws. I saw on another forum that these parts cost £190 and where fitted in 2 Hrs by a local mechanic as opposed to a main dealer. Try Cardiff (02920542400).

My plan right now is to get MB to complete the same conversion under warranty.

My goal is not to spend my evenings/ weekends looked at a compressor and wondering why its not working ..............or giving money to MB for zero service !!

TimH
 

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Further developments in the suspension saga. It will cost me £808 to convert to a normal suspension which will be hassle free. MB dealership says it's a 5 hr job. I have been on to MB again and waiting for a reply, what really gets me anoyed about this is that I have been told their could be up to 50 points causing this problem. £37.00 per hr to TRY find the problem and one answer from dealership was leave the vehicle with them for a couple of days now I would be MAD to do this as could work out at 8 hr average working day x £37 = £592. and they may never find the problem. I have already gave the dealership £250 and they can't solve I think at the present time I am being merked. There is one thing vehicle out their that did give me hassle free and that was a Russian vehicle called a LADA I had one for 10 years with a 100,000 miles.
 

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Low cost upgrade?

Buy the Vito rear suspension......coils/shocks......from German-Swedish, much cheaper than merc.......do it yourself!
But I would stick to the AS, much better if working! Try getting second hand solenoid magnets....most probable cause of your problem.....keep us posted and avoid merc dealers!
 

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Thanks for your advice. What is happening now is that the Air Suspension comes on and goes off for about a minute, but at least that's better than staying off alltogether. I sprayed the Electrical points and the compressor unit with wd40, I do not know if that will help. So if I buy the Vito rear suspension......coils/shocks that would do the trick? I note your advice to stay with AS but if the problem keeeps returning I will need to replace it. Replacing the solenoid magnets would that be a big job and would it be a dealers Job. Do you www sites for coils/shocks......from German-Swedish.

Thanks again for your help.

Sheils
 

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2007 W221 Brabus D6 III S320 CDi LWB, 2003 W220 500LWB & 1999 W202 240 Elegance Auto
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If anyone knows how to put a switch in to lower the suspension I would be interested, I know it was an option on them, the switch was in the boot
Thanks
Alan
 

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I contributed a whole A4 page today to this forum regarding the problems related to air suspension on V-class vehicles, but even though logged on, for some reason it has not been posted onto the site. I will try again later.
 

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I have read all the comments re air suspension and many are similar to those being experienced with my V230 - the slight advantage is I have a 5 tonne vehicle lift and a good fitter, so between us we will try to sort these problems logically and rationally.

I've had V230 Trend for 5 years and done 90K miles in it (total 108k). Originally air suspension worked perfectly, but after 3 years I noticed it stopped self adjusting after using vehicle or when first getting into it. Compressor seemed to work intermittently and I had to assist the pumping up by using the dashboard activation switch. Then the red warning light on the dash started to stay on after vehicle had been used and sometimes would stay on for days, even flattening the battery on a couple of occassions. However, once the vehicle was restarted and the activation switch used the suspension would pump up and the warning light would go out. Also, worthy of note is that during use of the activation switch the red warning light would change from continuous illumination to flashing at a medium rate. Once the switch was released the red warning light would go out and it was possible to hear the compressor working until the correct ride height (pre-set by the position of the sensor switches underneath) was achieved.

More recently however the system has ceased to function at all. When first starting vehicle the red warning light stays on and when the activation switch is depressed the red warning light flashes furiously until the switch is released, but the compressor does not kick in. Interestingly now though, the red warning light on the dash goes out within 10 to 20 minutes of turning engine off.

Like many of you we have checked most of the bits independently of each other, the compressor is OK, the sensor switches on the top of the link rods seem OK from a visual inspection of the insides - if you prise off the dust cover and the brass cover plate, inside is an electronic/magnetic sensor device the which acts like a proximity switch in that the centre rotates to a point where a signal is given to the control unit that a given point (and therefore ride height) has been reached. Having passed current across the solenoid valves adjacent to the compressor outlet, we cannot detect any movement from within and suspect that these are ceased/stuck in the open position (since air comes out of both valve ports when we hot wired the compressor.) We need to investigate this aspect a bit further.

We have also removed the control unit located behind the interior panelling in front of the o/s/r tailgate pillar. Nothing seems obviously wrong here, but no way of knowing without substitution for another (known to be) working unit to see if system behaves any differently with substitute unit in place. Several thoughts about control unit - we think it possible that with faults on system the control unit may go into some type of self protection mode to prevent damage to its programming, and may revert to normal performance once the faults on the system are rectified and the control unit is getting correct feedback from the system. Does anyone have any information on this aspect ? Does anyone have a control unit that we could substitute for ours to see if we just have a faulty control unit ? We realise that there is a danger here in that putting a good control unit into the system may then damage it if there are faults on the system that knocked out the original one ! but no one in their right mind would want to actually buy another one at whatever huge price unless it would definitely cure the problems.

We also feel that there must be a relay in the group of them behind the fuse board under the passenger seat that controls the power supply to the compressor, since the current to the compressor would be too high to go through the control unit, and from a safety point of view you would not want to route it to the activation switch on the dash. Has anyone any knowledge or experience on this aspect ?

If we cannot cure the faults then we agree that utilising the original air suspension is better than swapping to mechanical spring suspension, so what we propose to do is as follows:

1) Dis-connect the control unit
2) Pull the fuse that controls the system
3) Wire in a fuselink from the battery to a spring loaded rocker switch
4) Attach the switch to the drivers side of the passenger seat base and wire up to earth and the compressor.
5) Insert a tee piece into the compressor outlet pipe and connect the two ends of the tee piece directly to the airbag supply air lines (yellow and blue) thus bypassing the solenoid valves.
6) This should allow for safe inflation of the air suspension with care.

We haven't had time to devise a simple system to protect against over pressurisation yet but we are looking at it. In theory the system above should allow for a level ride height with self levelling taking place as the air balances from one side to the other via the tee piece.

We would wlecome any comments about any of the above, please let us know if we have made any glaring mistakes (I'll blame the fitter for those !). Would also welcome any feedback on any of the questions that we've raised.

Good luck to all V-class owners which is a cracking vehicle apart from the suspension problems.

TimD
 
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