Help with problem with Airmatic suspension on W212 E300

[Martin Hedges]

Friend of mine has a 63 plate E300 estate which has airmatic suspension on the rear (only I understand). Whilst his Mrs was driving it, it went down on the back completely. NO message on the dash. When the car is switched off and back on it says vehicle is rising but it doesnt rise and it doesnt sound like the compressor is firing up.

We have checked the relay and that sounds to be clicking in (checked with a multi-meter and got 6V on the switch supple) but there is no 12V feed across the relay. Checked the internet and it says there are 2 airmatic fuses - one in the front fuse box (no 12) and one in the rear fuse box (no. 68) but have checked both of those and they are fine. Have also checked with multi meter and there doesnt need to be a 12 V feed into the 68 fuse (which has continuity with the input feed to the relay supply), so it seems there is an issue with that 12V feed. If we hook the compressor to a 12V feed it runs OK and seems to have reasonable pressure behind it. Mate tried putting an airline to the outlet feed to see if that would inflate the suspension but wouldnt which suggests to me that the inflation valves were not open in the valve block (this was tried with the car running and the "vehicle rising" message on the dash which means that the compressor should be energised and the supply valves open. This also suggests therefore that the solenoids on the valve block are not being powered and hence a supply problem.

Can anyone suggest where to look next. Having checked the two fuses which are supposed to be for the auirmatic and both fine cannot understand why there is no supply. Have checked the control module in the passenger foot well and there is no fuse (that we can see) in there.

Any help would be much appreciated.

Thanks

 

[bembo449]

pumps do fail , id suggest getting it on star to properly diagnose the issue rather than guessing

 

[Martin Hedges]

Yeah I know pumps fail but it if the fact that there is no 12V supply to the pump / compressor. If it was running but not lifting then I could understand it but there is no supply to it, and it runs fine on a bench under a direct 12V feed

 

[bembo449]

have you got a power probe ? you could run the pump on the car connected and see if it rises

 

[Jonathon Wood]

it would of been the pre sam 60a fuse for the airmatic that would of blown. Old thread I know, but know from experience for anyone looking at this problem.