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One for the suspension gurus, harsh suspension with a twist
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gstuart
 


Member Since: 21 Oct 2016
Location: kent
Posts: 13576

United Kingdom 2005 Discovery 3 TDV6 Base 7 Seat Auto Java BlackDiscovery 3








Height sensors


Supply voltage. 5 volts - supplied by air suspension ECU
Output Vdc Left hand front and right hand rear - Decreases to 0.5 volts with bump travel. Right hand
Output Vdc Front and left hand rear - Decreases to 4.5 volts with bump travel
   
Post #204494910th Apr 2019 11:08 pm
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gstuart
 


Member Since: 21 Oct 2016
Location: kent
Posts: 13576

United Kingdom 2005 Discovery 3 TDV6 Base 7 Seat Auto Java BlackDiscovery 3

DSC SWITCH

Technical
What's crosslinked air suspension?
In low range, when one wheel is forced up as the vehicle crosses uneven terrain the air suspension forces the opposite wheel down, thereby improving the chances of it touching the ground and also increasing weight on it. Both are good for traction.

The DSC switch allows the DSC function to be selected off. Although Land Rover recommend that DSC is selected on for all normal driving conditions, it may be beneficial to de-select DSC, to maximize traction, under the following conditions:

If the vehicle needs to be rocked out of a hollow or a soft surface.
Driving on loose surfaces or with snow chains.
Driving in deep sand, snow or mud.
On tracks with deep longitudinal ruts.

The DSC switch is a non-latching switch installed in the center switch pack on the instrument panel. Pressing the DSC switch connects an ignition power feed to the ABS module. With the first press of the DSC switch, the ABS module disables the DSC functions. When the DSC switch is pressed again, the ABS module re-enables the DSC functions.

The DSC switch must be pressed for a minimum of 0.3 s for the ABS module to react. The DSC function is re-enabled at the beginning of each ignition cycle.

The status of the DSC switch selection is shown by the DSC warning indicator. The DSC warning indicator is off while DSC is selected on, and continuously illuminated while DSC is selected off.

A DSC switch request to disable DSC is ignored if the air suspension system has failed, or is in off-road height at speeds above 60 km/h (37.5 mph).

To guard against incorrect operation or a broken switch, if the input from the DSC switch is held high for more than one minute, a failure is stored in the ABS module.

Even if DSC is deselected, driving manoeuvres with extreme yaw or lateral acceleration may trigger DSC activity to assist vehicle stability.


HDC switch

On automatic transmission vehicles, HDC may be used in D, R and CommandShift 1 in high range, and in D, R and all CommandShift gears in low range. When in D, the transmission control module will automatically select the most appropriate gear. The vehicle should not be driven with HDC active and the transmission in N.

On manual transmission vehicles, HDC may be used in first and reverse gears in high range and all gears in low range. Once the vehicle is moving, the clutch pedal should be fully released. The vehicle should not be driven with HDC active and the transmission in neutral.
  

Last edited by gstuart on 11th Apr 2019 1:07 am. Edited 1 time in total 
Post #204495910th Apr 2019 11:35 pm
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gstuart
 


Member Since: 21 Oct 2016
Location: kent
Posts: 13576

United Kingdom 2005 Discovery 3 TDV6 Base 7 Seat Auto Java BlackDiscovery 3

Hi

Think that’s enough reading Rolling with laughter

Can’t find out yet if u have to select low gear to disabled the DSC , I always thought u could disable it in high gear but of course not 100% and always happy to be corrected if I’ve got my facts wrong

Hope this info may be useful and to others in the future Thumbs Up


EDIT

DSC

Yep I was wrong ,apologies Whistle

crosslinked only works in low Range

Technical
What's crosslinked air suspension?
In low range, when one wheel is forced up as the vehicle crosses uneven terrain the air suspension forces the opposite wheel down, thereby improving the chances of it touching the ground and also increasing weight on it. Both are good for traction.
  

Last edited by gstuart on 11th Apr 2019 1:07 am. Edited 2 times in total 
Post #204496010th Apr 2019 11:47 pm
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PROFSR G
 


Member Since: 06 Mar 2017
Location: Lost
Posts: 4581

Ukraine 2009 Discovery 3 TDV6 Commercial XS Auto Stornoway GreyDiscovery 3

[quote="gstuart"]
PROFSR G wrote:
White dust Gary Shocked
I didn't think you were into psychedelic gratification Rolling with laughter


Rolling with laughter Rolling with laughter

I wondered why people were waving at me Whistle


[/quote

Rolling with laughter Rolling with laughter Rolling with laughter
 yµ (idµ - eAµ) ψ=mψ

 
 
Post #204496110th Apr 2019 11:53 pm
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furnitureman
 


Member Since: 30 Apr 2015
Location: Stoney Stanton, Leicestershire
Posts: 1529

United Kingdom 2006 Discovery 3 TDV6 HSE Auto Lugano TealDiscovery 3

Do you sleep Gary 😂😂 some reading there I’ll Kay our what has been replaced below

All air bags about 2 years ago
All suspension arms, drop links and arb bushes last year from AF
New suspension compressor and relay last year from AF
New air tank
full v8 brakes upgrade last year inc all flexible hoses
Steering rack and lower column last year
Rear prop shaft last year
Cross climates fitted late last year

My accountant pointed out How much I spent on the old girl at our last meeting 😂

All suspension tightened up with wheels at correct height, then hunter wheel alignment done

I’ve played with tyre pressure and I’m currently at 31 front 33 rear but these tyres have a soft tread pattern anyway but the lower pressure feels better but not when going around a corner

It honestly feels like the tyres are made of mahogany when going over any rough roads but if I give it the beans up the very rough farm road it’s great 🙄

The car sits at the correct height after sitting on the drive all night and rises and lowers without problem, if I lower then rise and lower again it takes time to get back to odd road height but it’s always done that, when I start the car the compressor always runs for a while before venting the pressure from itself, not sure what other live values will be helpfull
 Range Rover Westminster 4.4 TDV8 what a car
Discovery 3 HSE 2006 gone but never forgotten
Member of the 234,567 mile club😎
 
 
Post #204499211th Apr 2019 7:23 am
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gstuart
 


Member Since: 21 Oct 2016
Location: kent
Posts: 13576

United Kingdom 2005 Discovery 3 TDV6 Base 7 Seat Auto Java BlackDiscovery 3

Hi

Rolling with laughter , with me recovering from the back surgery it’s been difficult trying to get usual sleep

Just thought I would make myself useful with the info and also gave me something to to Thumbs Up

Thks for the updated info

Interesting u saying about the suspension improves as the speed increases , is the battery and alternator ok

Only reason , is the correct voltage being supplied to the compressor ??

With live data , if u select compressor pressure and it’s voltage on the iid, can u have someone drive it for u so u can Monitor that the voltage and pressure is being maintained as u drive between lower and higher speeds

Plus have u checked ur brake speed sensors , via the iid to ensure all 4 x are working correctly
   
Post #204501011th Apr 2019 8:16 am
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Bardley
 


Member Since: 02 May 2018
Location: Hertfordshire
Posts: 437

United Kingdom 2011 Discovery 4 3.0 TDV6 HSE Auto Santorini BlackDiscovery 4

Surely the air pressure in the struts maintains ride height and unlike a conventional sprung setup, it cannot contribute to the harshness of ride given that the car is sitting at what has been described at it's correct level.
A hard spring (akin to what seems to be popular to be done to fiestas, polos etc,) will make the ride hard.
On an air system, more air will increase the height and only when at full extension, where the air bag units are fully extended and pressurised, then potentially give a hard feel.

My suggestion would be the damper units, even only one seized unit could give the sensation as described. These are clearly within the air struts, so full removal and deflation required. They can then be compressed and extended to feel their damping effect.
The upper and lower arms need to be checked for free movement to rule out any seized bushings also.
If the air units are disconnected at their lower end, the hub could be felt for binding in its up/down movement. The ARB will also need disconnecting at the drop links.


Report back on this one as it'll be a useful tip for anyone else having the same issue.
Thumbs Up
 2011 MY D4 HSE
Previously 2001 D2 TD5, 1996 D1 300Tdi, 1985 90 2.2 petrol.
Bikes! KTM, BMW, British, Classics and others.
 
 
Post #204517611th Apr 2019 7:43 pm
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gstuart
 


Member Since: 21 Oct 2016
Location: kent
Posts: 13576

United Kingdom 2005 Discovery 3 TDV6 Base 7 Seat Auto Java BlackDiscovery 3

Hi

Indeed u make some very good points , another reason it’s good for multiple people to throw ideas around with the set goal of sorting the issues out

Never know ref the struts if there past there best , my fronts were leaking air and had to replace them , the difference was like night and day

That’s what I was also thinking ref the arms etc, if the arms aren’t allowed to move freely

Wonder what the best way to test the springs would be without removing them

What do I think about using the iid for live data whilst driving alone to see if the compressor keeps at the correct pressure and voltages to each sensor , compressor , ie battery and alternator are working correctly

Also checking the ABS wheel speed sensors are also ok seeing it’s all part of the system

Indeed would be great to sort the issues out Thumbs Up

Know when going over speed bumps etc u notice it with worn out struts
   
Post #204518611th Apr 2019 8:20 pm
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gstuart
 


Member Since: 21 Oct 2016
Location: kent
Posts: 13576

United Kingdom 2005 Discovery 3 TDV6 Base 7 Seat Auto Java BlackDiscovery 3

Hi

Also just noticed that the air struts run at lower pressure to what the rest of the system does , I wonder if the valve blocks are slowly letting by allowing more air to get into the struts and therefore making the ride harder that it should be







But of course know ref the struts and how old they are , just pondering as u do Whistle
   
Post #204519511th Apr 2019 8:39 pm
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Bardley
 


Member Since: 02 May 2018
Location: Hertfordshire
Posts: 437

United Kingdom 2011 Discovery 4 3.0 TDV6 HSE Auto Santorini BlackDiscovery 4

As above, if more air was being allowed into the air units, then the unit would raise... and the overall height would change.
If the car is at its correct height, then any air added would change the ride height..

For harsh suspension look elsewhere than the air spring units. Dampers/lower or upper arms/bushes/ARB.
 2011 MY D4 HSE
Previously 2001 D2 TD5, 1996 D1 300Tdi, 1985 90 2.2 petrol.
Bikes! KTM, BMW, British, Classics and others.
 
 
Post #204525412th Apr 2019 6:06 am
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furnitureman
 


Member Since: 30 Apr 2015
Location: Stoney Stanton, Leicestershire
Posts: 1529

United Kingdom 2006 Discovery 3 TDV6 HSE Auto Lugano TealDiscovery 3

Thanks for all the input guys your going to love this update, since my iid tool got the update I’ve used the guided calibration when I’ve rebuilt the suspension or changed a height sensor, I’ve always marked the centre of the hub measured to the underside of the wheel arch and set the correct heights when prompted then I have saved the settings but the car always looks like the back is too high and it was if I measured it would always end up sitting at nearly 15mm higher than the correct height and the front was always 5-10mm lower.

So I went and recalibrated before I had the hunter alignment and it was the same too high at the back to low at the front even after setting the heights perfectly with the guided calibration part of the iid.

Here is the interesting bit, I decided to do a manual calibration and rather than get the chart out to work out what was what I just made sure the values for the front matched and did the same for the back no maths just a simple alteration of the numbers to match. I didn’t know which to use as the base so just went with one side and matched it, I then went for a drive around the farm parked up and the front heights are within mm of the correct settings and so are the backs the car sits nice and level looking at the front and back and it doesn’t look too heigh anymore at the back.

I then went for a test drive over my least favourite worn out road and it’s so much better the problem I have is that the suspend was so hard it’s shaken some panels loose so they vibrate but the difference is unbelievable I have no idea how but it’s staying with this calibration.

If your struggling with hard suspension and you’ve messed with the guided calibration it’s worth trying what I did to see if mine is just a fluke
 Range Rover Westminster 4.4 TDV8 what a car
Discovery 3 HSE 2006 gone but never forgotten
Member of the 234,567 mile club😎
 
 
Post #204621715th Apr 2019 6:37 pm
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robrs
 


Member Since: 30 Jan 2019
Location: Frinton On Sea,Essex
Posts: 36

England 2014 Discovery 4 3.0 SDV6 XS Auto Baltic BlueDiscovery 4

Gap tool arrived this morning and I’ve spent the day playing. There’s no codes showing. I adjusted the suspension hights with no success. I tried manually setting it all even that you had success with but it didn’t work and the car sat 12mm lower on the n/s. All the valves working ok
  
Post #204643416th Apr 2019 3:48 pm
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gstuart
 


Member Since: 21 Oct 2016
Location: kent
Posts: 13576

United Kingdom 2005 Discovery 3 TDV6 Base 7 Seat Auto Java BlackDiscovery 3

furnitureman wrote:
Thanks for all the input guys your going to love this update, since my iid tool got the update I’ve used the guided calibration when I’ve rebuilt the suspension or changed a height sensor, I’ve always marked the centre of the hub measured to the underside of the wheel arch and set the correct heights when prompted then I have saved the settings but the car always looks like the back is too high and it was if I measured it would always end up sitting at nearly 15mm higher than the correct height and the front was always 5-10mm lower.

So I went and recalibrated before I had the hunter alignment and it was the same too high at the back to low at the front even after setting the heights perfectly with the guided calibration part of the iid.

Here is the interesting bit, I decided to do a manual calibration and rather than get the chart out to work out what was what I just made sure the values for the front matched and did the same for the back no maths just a simple alteration of the numbers to match. I didn’t know which to use as the base so just went with one side and matched it, I then went for a drive around the farm parked up and the front heights are within mm of the correct settings and so are the backs the car sits nice and level looking at the front and back and it doesn’t look too heigh anymore at the back.

I then went for a test drive over my least favourite worn out road and it’s so much better the problem I have is that the suspend was so hard it’s shaken some panels loose so they vibrate but the difference is unbelievable I have no idea how but it’s staying with this calibration.

If your struggling with hard suspension and you’ve messed with the guided calibration it’s worth trying what I did to see if mine is just a fluke


Hi buddy

Am well chuffed u got it resolved , well done that man Bow down
   
Post #204645216th Apr 2019 5:22 pm
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furnitureman
 


Member Since: 30 Apr 2015
Location: Stoney Stanton, Leicestershire
Posts: 1529

United Kingdom 2006 Discovery 3 TDV6 HSE Auto Lugano TealDiscovery 3

Can’t quite believe it mate it’s not 100% but I think I’ve shaken the car to bits with it being so hard, only thing I’ve noticed is if I go to access mode front left wheel flashes red on the screen but all wheels are withinn 5-10mm of the correct height but it is just so much better, so much so I even aimed at some rough areas I normally avoid at the crashing was gone, some thing with cats eyes, I’m leaving it alone now 😂😂 thanks again for all your help
 Range Rover Westminster 4.4 TDV8 what a car
Discovery 3 HSE 2006 gone but never forgotten
Member of the 234,567 mile club😎
 
 
Post #204646916th Apr 2019 6:10 pm
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