Suspension Fault

[devo]

Hi all,

Have a 2009 Discovery.
Suspension light came on and was to busy at the time to sort it.
I drove for a few days and presume from reading here that it burns out the pump.
Noticed one day that the left front suspension was down more than right.
Decided to replace the front air springs and buy a chinese replica of the original pump to try before I outlay for the original.
Fitted air springs and pump but the pump wont run.
Nanocom fault codes are

U0164, UV0421, U0421.
Can anyone give me an idea where to start with rectifying this issue.
I try to do all my own work to keep me in-touch with my 185,000km disco but this has me stumped asI don't understand the suspension yet

Thanks for reading
Devo

[Eric SDV6SE]

These all appear to be comm codes, most likely due to the replica compressor you've fitted not talking to the BCM.

The Hitachi (and I think the AMK, but not sure, these were fitted to later models, so I'm pretty sure you have a Hitachi unit) compressors are fully rebuildable, you can get kits off Ebay that includes everything you need. most likely you've got desiccant dust in the lines or a leak somewhere.

Check that the airlines are fully pushed home into the top of the air struts and at the compressor outlets. do the soapy water check at each valve block.

Good luck

[loanrangie]

I doubt you need the new struts although they may be tired, more likely to be the front valve block and as Eric said the cheap pump.
Better off rebuilding your original compressor and putting it back in.

[scarry]

The valve block can leak back internally which is not an uncommon issue.

[devo]

Thanks for the positive responses.

Yes it is the Hitachi pump.
Yes. The message with the code was a communication problem. But where to start?

At the time of the original problem I didn't have a code reader so I was guessing and
I bought the Hitachi replica as i'm not sure if the original pump works still. I have read that if the fault light on the dash is ignored then the compressor motor burns out.
I am unable to check for air leaks presently as the pump replica does not run and therefore no air.
Is it possible to to check the old pump motor on the bench and if so what wires power the motor.
As for the valve body. Can the front valve body be overhauled or is it better to just buy a new one.

I feel I need to establish if the old pump motor still works.
As "suspension fault" was showing on the dash display and the old pump was not working I presume that the motor is burned out.

Any help appreciated
Graeme

[loanrangie]

If the light was still orange there's a good chance the compressor still works, when it gets to red and ignored it will run longer then burn out.
Valve block can be rebuilt with a seal kit but instead of stuffing around just buy a new one unless you have time to wait for parts.

[PerthDisco]

Check first the large main fusible link fuse in the engine bay fuse box closest to the front of the car. It’s a rectangle yellow colour 60amp or thereabouts. They blow with age and you can see looking above through the clear top. Then no juice to the relay or compressor.

You can bridge the big terminals (female side) of the EAS relay and force the compressor to run as another test.

They are big cables that run to the compressor main power feed.

[shamirj]

Does the valve block throw up a error message, I am guessing mine has a faulty valve block which can be bought for $100 approx from ebay cheapest or $400 genuine (referring to the fronts) only, but I do not get any faults when checked on the icarsoft code reader. My rears sag as well, so guessing I will need to replace both front and rear. cheers

[Plane Fixer]

I recently bought a genuine made in Japan Hitachi compressor from Island 4x4 delivered for just under $AU800 and fitted it last week. Solved my slow to raise warning. I did not consider the cheap knockoffs at that price.

[Bulletman]

Undo the power plug going to the compressor and run pos and neg straight from a 12v battery to the compressor , the compressor should run. You can then rule that out. check the relay, fusible link and the fuses in the engine bay, they are labelled under the cover .

The car will self level , so you may only have 1 leak but the car performs self level every 6 hours or so and this will cause all the airbags to deflate.

If you can get the car to pump up , pull the 20a fuse in the engine bay, this will stop the self levelling and you will see if the front or rear drops. A leaking valve block will see the front drop on both sides , a leaking airbag will drop only on that side.

Valve block rebuild is very easy , you tube is your friend, you just need to order the oring kit which you get from the uk , but after doing it myself recently i would think CBC or similar would have them on the shelf , you just need to get them out first to get the correct size.

I have also had a faulty brake light switch throw up suspension fault but the car didnt lower it just stayed at normal height and took out the ability to raise or lower the car.

Bulletman