Suspension flat / Fault code: 'B22/3(Rear level sensor) No signal'

[Nod]

Can you get the pump to run or test with the iCarsoft MB2?

I jumped the relay pins 87->30 and the pump kicked in, whilst pump was running with the jumped pins I undid the feed at the T piece on the rear axle and it was blasting air.
The new relay arrived, sadly no luck, still the same.

Think the fault must lay with the N97 unit or the length of cable from the N97 to the wheel arch. Kinda seems abit strange that it all sagged on a super rainy day, Guess really I got to check the length of cable that runs from the N97 to the wheel arch for continuity. How do you get access to it though? It looks quite high up and hard to get to.

Does the N97 need coding to the car with STAR if you change it with a replacement unit?

 

[Snake Charmer]

N97 according to Star Finder lives on the aluminium tray in the passenger footwell, LHD car shown.

 

[Nod]

N97 according to Star Finder lives on the aluminium tray in the passenger footwell, LHD car shown.

Thanks alot for that Snake Charmer, I thought it was the black unit on top but wasn't totally sure as the one in the metal casing(with white connectors) also seems to be called 'Air Suspension Control unit module', which is abit confusing. I think the one with the white connectors is for the ESP though. I will try and backprobe the signal wire(in the black top unit), which I think is coloured blue and white (although not sure totally), if anyone knows what one it is?

It did something strange yesterday, started the car and noticed that the pump had actually come on, it was only after I stopped the engine that I heard the pump running. It continued to run for about 1 or 2 minutes even with the engine off, which seems rather strange. Even though it was running, it did not inflate the airstruts(both sides still totally flat as a pancake).
Think it can only be either a broken lead that is not supplying a signal(as fault code states) or the N97 Control Unit itself has gone bad.

 

[Snake Charmer]

My stored 53 reg S211 with the saggy rear end starts the compressor when I open the door, it runs for a short while and you can hear pressure building as the motor loads up. The rear end stays on the floor until I start the car but has sat with the compressor running and not risen a couple of times with no dash message nor any codes.

 

[Nod]

Aah, I see, maybe thats normal then.
I will get to the ECU module tomorrow and try and get a signal reading off the wire.
Think it is the blue and white wire from what I can see from browsing the internut... but not totally sure.

 

[Snake Charmer]

I have sent you a PM.

 

[Wearsafoxhat]

Have you checked th wiring at the compressor end. One connector I’d the supply and the other is part of the control cct… apologies if you have as haven’t fully read the post as in a hurry this morning..

 

[Nod]

Have you checked th wiring at the compressor end. One connector I’d the supply and the other is part of the control cct… apologies if you have as haven’t fully read the post as in a hurry this morning..

I will get the thing jacked up and expose the compressor and check the wiring as you say, as well as getting to the N97 and having a probe of that.
Thanks for the help and ideas, much appreciated.

 

[Nod]

Have you checked th wiring at the compressor end. One connector I’d the supply and the other is part of the control cct… apologies if you have as haven’t fully read the post as in a hurry this morning..

Had the compressor on and off to clean up and check over. It fires up when you jump the relay as said, so appears the power connector is fine and supplying voltage. Just wondering, the other 2 pin 'Controller?' plug, what sort of voltage should that measure? what does that actually do?

 

[Nod]

Just tested for voltage at the ECU on the Blue/white wire which I think is the signal from the sensor. Is signal of 2.9v which sounds about right.
Assuming now its the ECU thats faulty, as it seems it is not sensing the signal even though 2.9v is there, as in original fault code message "B22/3 : Signal Failure".
I think the ECU being faulty is the only thing left, or am I missing something?
Also on the 2 pin plug(controller as said above) into the pump, there is no signal or voltage at all on that.

 

[Snake Charmer]

There are solenoid valves within the pump so a logical guess would be the other "controller" plug is for those.

 

[Nod]

There are solenoid valves within the pump so a logical guess would be the other "controller" plug is for those.

That's interesting and maybe explains that when the pumps runs and doesn't pump up the struts because the solenoid valve has not been opened in the pump. Assuming that the ECU triggers the controller to open up the solenoid thus enabling inflation. Think my ECU is not interpreting a signal(even though it is there(2.9v)), therefore not triggering the pump or solenoid into action.
I will try another ECU and see if this solves the issue, if not I am stumped!

 

[Snake Charmer]

Any luck with your car?

 

[Nod]

Any luck with your car?

Heya

Still awaiting on the N97 control unit to arrive. Its been off the road for over a month now, just hoping this replacement unit solves it.

Surprisingly I got a replacement off Eboy for just £15 quid, thought I may have to pay alot more than that, so thats something I guess. I will update with the results when the N97 arrives... fingers crossed.

 

[Snake Charmer]

I was thinking yesterday about the suspension lock and odd compressor start my other car has done. Nothing in the handbook I could find about jacking the car and suspension lock, the info I read about the suspension mentioned the wheel sensors and rotation plus door opening used for the resetting the lock. Have you moved the car since tge fault happened?

 

[Nod]

The replacement N97 unit arrived, sadly no difference on fitting that one. Kind of stumped, I guess I need to get it on STAR diags? Problem is think its probably too low to drive it there and may need a costly trailer.
I will get the wheels back on it and see if its drivable and also may reset it or something, re, Snake Charmers idea above- worth a shot for sure.

Just wondering if there is a way I could inflate the struts with a compressor line or anything by disconnecting the car pump feedline and hooking it upto compressor instead? Or will the solenoids in the struts not allow this? That may at least get me up my local garage who I think have STAR.

 

[Snake Charmer]

Does your iCarsoft unit not do suspension testing? I plan to cut the air spring plugs off my spares car later this year so I can make a lead up to allow me to test the air springs, I just need to confirm the solenoid feed voltage.
Where abouts is the car located?

 

[Snake Charmer]

I mention moving the car as when the suspension is locked with no dash warnings the system reads the doors and boot/tailgate switches plus rotation of the wheel sensors from what I see to override the suspension lock. It may not relate your problem but my car wasn't happy with an axle stand under the towbar and left the car on the floor with no dash warnings.
Have you tried locking the car with all the wheels on and leaving it a while then unlocking, getting in and starting? You may get a dash message, if not it might be worth trying to move the car and see if the pump starts.

 

[Nod]

Thanks for the help again Snake Charmer (and all).
I just put the wheels on and got the jack out and strangely one side does seem higher then the other. I am beginning to wonder if the lower of the air struts has failed.
As for the Solenoid in the struts, I think its 12v but a 9v battery will open it. I used this method when I had to deflate the struts to change them. I was thinking of unplugging the solenoid connector, hooking a 9v battery upto it(to open it) and jumping the relay on the pump to blow it up and then see if it deflated (which is probably the method Snake Charmer is suggesting above).
Something for sure seems to have stepped out bigtime but you never know it could just be that one strut has failed and it has had a knock on effect to 'weirding' everything out and making the car sit low.
Luckily I have a friend who is a mechanic and he is going to bring his Snap On diagnostic unit up and see what that says.

In the meantime I may try and open the solenoid with a 9v battery and jump the relay to inflate the strut and then see if it leaks back out.
Problem with this is that I did once ruin a solenoid by shorting the pins out, as when you poke bits of wire in there is hardly any room and you can accidentally touch them, so will be much more careful this time, may even use thin multi meter probes hooked up to 9v battery to do it.

 

[Nod]

Well, seems like we may have worked the issue out...
My friend came up who has the cool Snap on diagnostics kit and it went into alot more detail than the Icarsoft MB2, as one may expect.
We deduced that the right airbag was not getting a signal to open solenoid. Closer inspection found the right airstrut completely deflated and had even come off the mounting . This in turn had I think made the whole setup confused with one side sitting higher than the other and just one sensor gaining a figure for the 'average' of the sloping axle. Not sure of the ins and outs of it all but the whole system appears to have stepped out as well as me disturbing every single component in the system it seems, rear sensor, relay, N97 unit and the pump itself.

Think where the air strut had completed deflated (it had a leak caused by the plastic housing snapping on the Aerosus strut and puncturing the bag). This in turn was so deflated that it was hanging limp and had further dislodged the electrical plug for the solenoid somewhat disturbing the connection. I pushed the plug back in and once the door was shut (part of wake up process as Snake Charmer has described) the thing attempted to deflate. Sadly, my finger was above it and it gave me a right scare when my finger got trapped in it. Luckily got it out with only a bloodied finger to complain of! Small price to pay really for getting to the bottom of the problem!
Further more, the Snap on diagnostic unit seemed great, you could even inflate or deflate either strut to test it, left or right! I think it may also let you input ride height levels to program the ECU but not sure exactly as did not have too long to look at it all.

Luckily I do have TWO new unused Aerosus struts but they have damaged solenoid valves/plugs.
Does anyone have a pair of solenoids they may want to sell? They are the smaller Rapa types (see pics), not the large circular ones.


I can possibly get some from Europe but would rather try here first.