Guys,

Has anyone ever changed the air suspension ecu before? I have a Range Rover which will not sit correctly, it tends to want to lower the front suspension and raise the rear.

I have checked every input sensor with an oscilliscope, the readings are fine so I can discount the sensors, I also checked the wiring to the suspension ecu from the sensors by carrying out voltage drop tests - all of which were good.

I have the IId Tool and Hawkeye, I am able to actuate the 4 corner valves perfectly, I can also exhaust excess air when I want. Pressures from the compressor look good, as do reservoir pressures, temperatures etc.

I cannot find any leaks from the bags. I checked the suspension ecu and noticed that someone had previously connected something to a number of the cables (no doubt a phone kit).

In absence of any other faults, I am beginning to think that the issue is at the ECU itself, even more so after finding the marks in the wire were someone has utilised the dreaded scotchblocks connectors.

Can anyone advise me if they have changed the air suspension ecu, and if they did - did they have to code it in?

Many thanks,

Stephen

Hi Stephen,
I assume this problem happens when the vehicle is parked for a longer period? Can you check the current height and current calibration with the IIDTool before and after leaving the vehicle?

Christian (chief engineer) saw this thread and the consensus at GAP is that the ECU as a cause is unlikely. It sounds as though the valves are allowing pressure to bleed from front to rear. A good check would be to incapacitate the EAS ECU by going to the test valve function in the IIDTool and exiting the menu without leaving test mode. Or you can simply disconnect the battery.


And from the Manual;

When a new air suspension ECU is fitted, the air suspension system will not function until configured with TestBook/T4.

A used ECU might work without initialization (depending on the mode it was left in) but would still need a calibration (IIDTool). 
RRC 2Dr, RRC 4Dr,
P38, and 2 L322s
(wife thinks I'm nuts - prob right, too)

Hi Steve,

Thanks for the detailed response, unfortunately the vehicle squats down even after we have just calibrated it using the IID tool.

It does not matter how long the vehicle is left for.

I thought along the same lines as yourselves with regards to the test function. Indeed when we use the IID to set the level manually, and exit without leaving test mode the vehicle will indeed sit level, the airbags show no sign of leaks even after leaving them a few days. Problem is as soon as we drive it, it throws up suspension disabled (the fault code states articulation).

We have double checked the physical condition of each of the height sensors and have recorded a good waveform output from each sensor - at the sensor and at the ecu.

We are pretty switched on over here, and have the advantage of being able to use a picoscope to verify output signals etc, I am waiting for some more back probes to arrive so that we can look at some live data to find out more information.

Any further advice would be appreciated.

Many thanks,

Stephen

Hi Stephen,
Can you post the current height and current calibration values when you exit the vehicle - and then confirm that it goes nose down (so that we can see what we are working with)? 
RRC 2Dr, RRC 4Dr,
P38, and 2 L322s
(wife thinks I'm nuts - prob right, too)