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
