A few have suggested I bring the car to you Craig but sadly as your so far away its not possible.

It would be interesting to know what your process to diagnose this would be.

I can't see Craig but I imagine he is looking worried!  overfinch modified

Just to close-out the Defender hard suspension digression, the 2nd dealer confirmed the Gap tool's live value display of 0V to all CVDs while driving so a new chassis module has been ordered. It's taken 7 months to convince a dealer of a problem but at least the issue is now being addressed.

Hopefully the new module sorts it for the owner Graeme

I wish mine and the others problems were as simple as a module not outputting the correct voltages.

Had to do a 2 hour drive today to go to a suit fitting for a friend's wedding.

The suspension was the hardest it's ever been during todays drive.

Almost as hard as when you disconnect a shock and force an adaptive dynamics fault.

I pulled up the live values for damper current and duty cycle and they were as expected but looking at them got me thinking...

We can see a signal is being outputted and theoretically this is reaching the shocks as the module would know if any were open circuit but the signal sent is a PWM signal is it not?

What if the PWM signal outputted is not correct or faulty in some manner?

I dont think live data would show this...

Would an oscilloscope me needed to check the PWM output?

I can remember when I had my problem vehicle with the gap tool that there was a live data output that showed if dampers were hard or soft ! Is that something you have come across ? Last night I lay in bed looking up at the stars in the sky and I thought to myself, where,s the f**king ceiling!!

Yes that's what I was looking at ref my post above.

The current being sent is 1.5 amps varying over bumps slightly (which is correct)

And the duty cycle is on average 32-40% for the fronts and closer to 40% most of the time for the rears.

But the iid tool doesn't show the actual status of the PWM side of the signal so either that's bad on all our cars or assuming the shocks are genuinely good and the signal to them is good would be the problem lies elsewhere.

Nobody can tell me that how my car drove going there and coming back today is 'normal' or 'that's how they all drive'

As an example I don't think our late her majesty would have accepted such poor quality.

(Yes I know she favoured a 1st facelift L322, so do I!)

I know little on how PWM signals work, so had a google.
There’s quite a lot of science involved, but found some good ‘simplified’ articles. My very simplified overview is that the amount of power sent to the struts is controlled by the percent of time the voltage is either on or off. I’m not sure of the frequency, but this on/off cycle is likely several thousand times per second. Hard strut = 0% of the time power is sent, soft strut = 100% of the time power is sent, and a medium strut would be 50% of the time power is sent to the strut… and of course variations of this frequency varies the stiffness of the strut.

The bit I am still unsure of, is what effect poor cables have on the PWM signal. Cables can be damaged and also degrade over time causing their resistance to increase. As that resistance increases the voltage drops, so surely the PWM load would also decrease as those cables age?

Do we have an issue which is simply caused by cable degradation? Or damage? We often say the rears seem harsher than the fronts… is that simply due to longer cable lengths?
Or even is one strut affected, causing the system to interpret that somehow as needing to stiffen the rest of the system?

I am no expert in any of the above so please do correct me where I’m wrong. Currently driving: 2012 L322 SE Overfinch 4.4 tdv8

Past rides:
2014 Audi Q7 3.0d (good riddance)
2010 L322 Autobiography 5.0 Supercharged
2011 L320 HSE 3.0 sdv6
2014 Jaguar XF-RS 5.0 supercharged
2007 BMW 535D
2005 Mini Cooper S

https://www.fullfatrr.com/forum/topic59478.html

I've ordered a second hand chassis control module just to see if it acts any different with that fitted.

Hopefully they aren't VIN locked but if that's the case I should hopefully be able to return it.

https://www.rangerovers.net/threads/l405-c...ed.358280/

Might need some sort of reset.


The more I read the more I’m inclined to think earthing somehow to be honest. V8 or else ...

I've tried updating both the CHCM and CHCMB to the latest firmware with thanks to Pat and GAP but to no avail.

I dare not try the whole configuring like it's a new module thing as per that thread you posted Fisha as my SDD setup and cable are chinese clones and I can't afford to risk it bricking the entire car.

I'm awaiting delivery of a second hand CHCM to try.

Need to start logging everything I've done/tried in a document as suggested by the chap on Facebook I was speaking to.

You could use a DC clamp meter around the wire that supplies 12V power to the CVD section of the module (brown connector, RH end, large dia wire up 1 row from the bottom) while someone watches the change in current from when stopped to when barely rolling. You would then know the total extra current drawn by the shocks when the bypass valves are meant to be at least partially open as a means of confirming that the shocks are consuming power when they're supposed to be. Alternatively wire-in an ammeter in place of the CVD fuse with wires long enough to allow the ammeter to be seen whle driving.

Received and connected the second hand CHCM tonight.

As expected the car throws 'air suspension fault max 30mph' probably due to the module coding not matching my car.

The module does function though in that it outputs signal to the dampers and I was able to calibrate the suspension height (needed to be done as this modules existing calibration was tailored to the vehicle it came out of)

The ride feels perhaps a tiny bit softer but barely any different really and certainly not a massive improvement like I'd expect if this was a case of a duff module not outputting correctly to the dampers.

So I guess that rules out the module itself being at fault, I've left it connected for the moment as I want to see if there's any difference in the morning with my usual feeling that the suspension is ever harsher when first setting off for work.

No different this morning, still a stiffer ride first thing with the replacement control module.

I think that rules out a random control module fault so it's back to looking at the inputs to the module etc

Any ideas on a signal that's used by all 3 things?

I.e. the damping, steering and engine?

Obviously vehicle speed is the big one but I've checked the live data and that looks fine.

I've been following this and the other topic on the L322 forum for a while. I'm still not clear exactly what the system is supposed to do as using variable damping seems to be mainly about controlling roll in cornering which is a bit of a fudge compared to more modern systems on cars which have active spring rate and ARB controls. I had a similar setup on my old Audi Allroad - variable dampers and air springs but the system was user selectable between comfort (normal ride height and soft dampers) and sport ( lower ride height and harder dampers) Unintuitively the comfort setting was much better at speed in terms of comfort and the sport setting was more comfortable at low speed around town where the comfort setting was harsh and crashy. Mine had low profile 19" wheels which were I think ultimately why it was crashy and was the main reason in the end why i bought an L322. I have suggested before that low speed comfort is more down to tyres (sidewall compliance) than dampers and a combination of worn dampers and low profile tyres or low compliance ( all terrain) tyres will feel harsh. Mine is 'acceptable' most of the time and is still on original dampers at 160k miles but runs on 255/55 R20 Verde's. My biggest improvement in comfort was when I swopped all 4 tyres out for newer versions of the Verde which were either better designed or the old ones had hardened with age ( 7 years old) 2012 TDV8 Vogue (L322)