air suspension pump problems 4.8is

[pieter4458]

I sit with a problem that is not the normal air strut leaking or car lowering problem, but the following:

1. The suspension height level stays constant at 715mm over a period of 2 months. The only change I can see after a drive is +-5mm on any side.
2. The air suspension inactive warning is on and the height control switch is inactive.
3. when getting into the car or switching ignition on, the pump can be heard for a few seconds and then stops.
4. The height back or front stays the same, regardless if the pump works or not.
5. Removing and replacing the 30A and 7.5A fuses have no effect at all
6. When doing a air suspension "reset" with the normal dealer software (GT1) reveals a error with the filling of the compressor and inactive pump.
7. The reset only last a day and then the inactive air suspension message comes back and an inactive control height switch.

My problem is that i do not want to buy a new pump if it is the air suspension control unit and vice verse. It can also be the pressure switch?

My car is the 4 corner, dual axle type.

WHERE SHOULD I START LOOKING FOR SOLVING THIS PROBLEM?

[Ricky Bobby]

Scan your car again and post the error code.

Most likely your compressor is out of spec, I had same symptoms as yours, compressor would run, but inactive was shown on dash, height control didn't work, etc. My car always stayed at the same height.

My error was EHC 74 accumulator filling requested (pressure remains constant) and it was because my car was driven for too long with leaky air bags and burnt out the compressor out of range to be workable.


Sorry to say but I think you need a new one, Arnott sells them for 510 and you can find a coupon code for 10 percent off usually. Replace the compressor (if your error is what I had), and reset the air suspension with GT1. Your ride height should work then!

[pieter4458]

The error code you mention is the same as mine. If I am not mistaken then it sounds as if the pump is pumping against a resistance as it starts good but slows down just before it stops. The BMW technician who did the reset also suspect the pump.

How difficult is it to DIY the replacement of the pump ?

[Ricky Bobby]

Originally Posted by pieter4458

The error code you mention is the same as mine. If I am not mistaken then it sounds as if the pump is pumping against a resistance as it starts good but slows down just before it stops. The BMW technician who did the reset also suspect the pump.

How difficult is it to DIY the replacement of the pump ?

Yes the compressor still pumps, however it is no longer within "tolerances" of spec for the computer, takes too long, etc, and throws the error and renders the air suspension useless.

It takes longer to take the spare tire out than it takes to replace the pump, one harness and one air line, and a few 8 or 10mm bolts on the "hump" as well to get it opened. If you go on Arnott Industries website they have instructions for replacement with photos.

[pieter4458]

thanks for the advise. Please help with the following questions:

1. If I disconnect the air pipe from the compressor, will the air suspension deflate?
2. How do I get the pipe out of the quick coupling? Push in and pull or how?

[Ricky Bobby]

1) No. There is air in the accumulators which keeps the suspension inflated
2) Push down on quick connect with a flathead or something and pull air tube out.

Directions here:

https://www.arnottindustries.com/fil...617&Size=SMALL

[sockethead]

I had that same error.
I replaced mine with the Arnott compressor a few months ago.. It comes with excellent instructions and the tool to get the quick connect fittings off. You can also use the same tool used for quick connect gas lines. It's extremely easy to swap out.

Once swapped, erase the error in GT1 and you should be good to go.

The Arnott pump IS the OEM pump BTW

Here are some PICs... It looks like a lot of stuff to disconnect but most of it comes off with the bracket as you can see in the second pic.

[pieter4458]

Feedback time. I took the pump out and did some test on it. My problem is I do not know what the spec should be:

1. The pump works very good on 12v and there is no noticeable decrease in speed after a time of continuous running of 2 minutes
2. The pressure on the pump as tested with my limited equipment reads +- 4 bar or 58 lb/in2.

Question: is this normal or should I now start testing something else?

[sockethead]

Originally Posted by pieter4458

Feedback time. I took the pump out and did some test on it. My problem is I do not know what the spec should be:

1. The pump works very good on 12v and there is no noticeable decrease in speed after a time of continuous running of 2 minutes
2. The pressure on the pump as tested with my limited equipment reads +- 4 bar or 58 lb/in2.

Question: is this normal or should I now start testing something else?

Just replace the pump I was thinking the same thing: why replace a pump that appears to be working normally. MY Gf works at a BMW dealer and even they didn't know how to test the pump...

[Ricky Bobby]

Originally Posted by sockethead

Just replace the pump I was thinking the same thing: why replace a pump that appears to be working normally. MY Gf works at a BMW dealer and even they didn't know how to test the pump...

X2, the pump does work and it seems that it shouldn't be replaced because it runs, pressure seems good, etc.


The problem is the pressure is not "great", just good, and it does not operate within spec of the control unit and must be replaced if you have the error that socket and I had. Its the only way.