https://www.gap-diagnostic.com/wordpress/w...lV4.00.pdf
Page 96 onwards, the calibration formulae are on page 101 onwards.
I'd recommend getting an old centre cap and drilling a hole in the exact centre of it, bonding a metal pin or old 2 or 3mm drill bit into it and using that on each wheel as you need to be very accurate (to the mm) with the measurements.
Also
https://www.gap-diagnostic.com/wordpress/w...lation.pdf

I don't have or use IID so can't give you any guidance, there's plenty of 'long term beta testers' on here that should be able to talk/type you through it.

I've got a old cap so ill use that ,had a read (thanks) think ill have to read it a few more times to get it straight in my head lol .at the beginning of the week i did notice that when ever i tried the compressor it would start and then stop checked a few things and looks knackered so replacement sourced fitted and it now runs as it should (1 problem sorted ). now the other thing somebody said to go into test value's and try to get the wheel numbers as close as possible to "0" so anyway i did give it a go .........now when i alter the rear i can get it to move both up and down no problem .....but.... when i went to to the front nothing the compressor starts and runs but the front wont move up or down and i get suspension fault .so my thinking as that i have a problem with the front valve block which i have already refurbished new seals infract did them all 4/5 months ago .would go with my thinking or am i way out ??????

If there was an issue with the valve block, then I'd expect DTC's to be set - have you got the arm on the height sensor you replaced the correct way round? and for the correct side?
What DTC's are you getting? - not the internal IID errors.

ETA - also check the fuses and holders for corrosion, volt-drop across the fuses can cause all kinds of oddities - don't forget the one in the rear fuse box.

the height sensor was replaced last December and that cured the red flashing marker i was getting on that corner so don't think the height sensor is at fault ...hoping to jack the car up tomorrow and check the valve block -air lines/connectors and wiring (weather depending ).dtc ? do you error codes ? if so i get suspension fault on dash that's it outside of gap tool

DTC = Diagnostic Trouble Code = error code
Which one(s) are you getting? Ideally a whole vehicle scan, not just the suspension. They'll begin with a U, B, P or C - 'E' are specific to IID and meaningless in this context.

Before you go mad jacking up the car, check the fuses - also check the control module for signs of moisture ingress.

when i get a chance ill pop them in

right on going suspension problems..... one issue now sorted can now change ride heights, how ever over night the car drops on all 4 corners .put to off road height removed eas relay in boot in the morning the front had dropped rear still up (getting somewhere maybe) front valve block or leaking bag or air pipe .....so put the relay back in and i was expecting the back to drop when left overnight but it hasn't,i was expecting the system to off dropped to level its self out anybody know why it didn't ??????


I've got a valve rebuild kit coming when when it stops raining ill do that and all so try the soppy water again and see if i can see any leaks

Right replaced front valve block seals(again) and also fitted new height sensor (genuine)front now stays up 👍
Rear valve block next as back drops overnight 👎🏻
Have reflashed suspension ecu and firmware update on gap tool calibration error code gone 👍👍.

So once I have sorted the rear dropping I wil calibrate