I am from Adelaide, Australia and this is my first post on this forum.

I have an air suspension issue with my 2003 L322 Range Rover. There have been lots of posts on several forums describing this same issue but no one seems to have reported a solution. So I am looking for any assistance.

After almost two years of relatively trouble free L322 motoring, I experienced a sudden drop in the front left (FL) air spring while turning a left corner whist towing a trailer. The ride height did recover and I was able to keep on driving but the problem progressively got worse and the FL now drops noticeably lower than the other corners.
A check with an iCarsoft i930 diagnostic tool showed the signal voltage from the FL height sensor as being an implausible 43 volts and the height a minus 14 mm. The other three sensors were reading about an expected 2.5 volts.

After jacking up the FL side for an inspection, there was the sound of air escaping from the air spring when the jack was let down. So I replaced that air spring.
As the L322 air spring and its air line connection is shrouded in a tower, it is almost impossible to visually check it for leaks with soapy water in situ. I was able to check the air spring and the air line feeding it for leaks at the front crossover valve using a Schrader valve connected to a 6 mm push on fitting. However that is another chapter that I will write up later as well as my experience in fitting the new air spring onto an existing strut.

My current issue is that although the FL air spring does not have a leak and that corner rises to approximately normal height but will constantly lower it self when I start driving. This happens even when the ECU is disabled. Using the iCarsoft i930, no faults are reported. It does however still show the signal voltage from the FL height sensor being approximately 43 volts and the height being a negative 14 mm.
I have back probed the FL height sensor connector and it reads 5 volts across the supply pins. Disconnecting the linkage and moving the sensor arm up and down, the signal voltage moves as expected from about 0.5 to almost 5 volts. Back probing the connector on the EAS ECU, I found the same plausible signal voltage there. I even checked with an oscilloscope to see if there was any interference on the signal wire and it was pure DC without any noise.

My conclusion is that the ECU has a faulty A/D convertor for the FL corner. The signal voltages from the height sensor seem to be normal so I think the ECU must be misinterpreting the signal from the height sensor as being 43 volts and then proceeds to adjust that corner.

My question is, has anyone successfully replaced an EAS ECU on a L322?
A note in RAVE says - “When a new air suspension ECU is fitted, the air suspension system will not function until configured with TestBook/ T4”.
Does anyone know if an ECU from a donor vehicle will work without needing to be configured by TestBook?

PS I did further testing today and am now thinking I might have two separate issues. As well as the ECU calculating a negative spring height, there seems to be a clue to an internal leak within the valve block. When I disable the air suspension by removing fuses 57 and 18 which are the supply to the air suspension ECU, valve block and compressor, the FL height still drops when the car is backed out onto the road. I had expected the valve block to retain pressure in the FL line like it does on the other corners as the valve in the valve block should not let air past if its solenoid is not energised.
I would appreciate any input if someone has been down this road before.

Cheers
Richard