4.8is Air Suspension Compressor Gets no power

[brucemillar]

Folks

I have searched and posted to no avail. My 4.8is has the Suspension Inactive Message on the display. The suspension is "inactive" this started with no warning (excuse the pun). Working one minute, failed the next.

* The car is not sagging. I do not suspect a leak.
* the ride height switch is NOT illuminated - suggesting the system is dead?

I have checked all the fuses I see listed, two in the boot and two in the glove box. I also replaced all four with new tested fuses. All are good.

* There is no power to the compressor.

On the right of the spare wheel there is large white loom connector for the compressor. If I check there? I have no voltage. Note: I checked this with the ignition on and all doors, including the tailgate closed (it gets warm in that space)

* If I take 12 volts from the battery and connect to the black wire on the white plug. The compressor fires up.

* I have checked voltage all the way to the compressor pump. There is none, zero, zilch.

* I have checked the fused links behind the rear seats on the left of the boot (blue box with white lid). Continuity is good on all of them and all have 12+VDC with ignition on.

Is there a fuse that I have not found? With the system completely dead? I am sure that I have blown link or fuse or relay upstream from the actual compressor itself - hence no power at the boot plug.

I have seen mention of a relay, but cannot find one in the compressor dome. This is four corner system as standard on the 4.8is and NOT the rear only system fitted to other models.

I need to know where the fuses and relays are that could be killing the power ahead of the boot?

How can I raise the car in an emergency?

I can get power to the motor but it does not seem to lift the car.

[Awntchi]

Your compressor must have been working overtime and eventually shut down from overheating. Check the bags all around...spray soapwater on them for leaks and go from there. The compressor won't come back on unless it's reset through a diagnostics tool, activating it like you did won't do anything as the whole system needs to be in sync.

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[williamx5]

Good day!!

I discovered that if the suspension inactive message comes up, it will not go away until you reset the system with INPA or similar software... That is all I did with my 2-axle air ride that died on me... It fired up and stayed working... I only found this out AFTER I swapped the air ride over to sport coil springs... I did swap back once I found out the trick to reset it... I went into INPA and manually adjusted some corners and cycled between the different modes... If you have 2-axle (I think all 4.8is' do).... Your control module is behind the glove box... I did not have power to the compressor either, until I reset the system...

As far as getting the ride height correct in an emergency, I pulled the connectors and jumpered the different corner actuators... I don't recommend doing this!!! I'd just find someone that has INPA to reset the system (or whatever other software will work)... You can read the fault codes as well... So you don't have another failure to leave you as you are now...

Good luck!!! Let us know what you discover...

Cheers!!

[brucemillar]

Awntchi & Williamx5

Thank you both very much indeed. You have saved me a world of pain and time. This was driving me crazy, tying to find a relay or fuse that does not exist (from your posts).

I will get her re-set then check for leaks on the bags. She is sitting low now on all 4 corners but is not on the bumps stops as the ride is not harsh or bumpy. It has taken a week for her to get this low so I guess if there is a leak it is very slow one.

I may just buy the compressor kit from bagpipingandy and do that job while I am in the boot.

Thank you again gentlemen you have both been very helpful.

Bruce

[brucemillar]

Awntchi & Williamx5

I took the truck to my local Independent BMW Garage yesterday. They re-set the suspension using their diagnostics and VIOLA, the error cleared and the car raised itself up and leveled itself out.

Many thanks to you both for your responses that were absolutely on the money.

The garage reckon my compressor pump is on it's last legs as "it is taking way too long to pump up the bags".

I will get the kit from bagpipingandy on ebay. That should sort this out.

They are confident that if I disconnect the battery "before" I take the pump apart. The system will not need another re-set when I switch it all back on?

Thanks again.

Bruce

[Awntchi]

We're glad we could be of help. Let us know how it goes once you install the refurb kit. Remember to check the bags though, it's most likely a leak somewhere.

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