DISCO3.CO.UK - View topic - Keeping the suspension "UP".

heine

Member Since: 07 Feb 2007
Location: Midrand
Posts: 4054

2009 Discovery 3 4.4 V8 HSE Auto Alaska White

I'd volunteer but I guess you need someone a bit closer

28th Nov 2008 10:07 am

caverD3

Member Since: 03 Jul 2006
Location: Oberon, NSW
Posts: 6922

2012 Discovery 4 3.0 SDV6 SE Auto Fuji White

yes!

If it gets up it will be in a kit and could be posted.

â€œThere are only three sports: bullfighting, motor racing, and mountaineering; all the rest are merely gamesâ€
Ernest Hemmingway
D4 3.0 Active Diff, Adaptive Lights, High Beam Assist, Surround Cameras, Privacy Glass.
D3 2.7:Adaptive Headlights,Electronic Rear Diff,ARB Bar,Blaupunkt Speakers,JVC Powered Subwoofer,Removable Snorkel,Mitch Hitch,Pioneer After Market Head Unit,Steering Wheel Control Adaptor,Remote Adjustable Supension Rod System, Taxside Dual Battery System.

28th Nov 2008 11:02 am

heine

Member Since: 07 Feb 2007
Location: Midrand
Posts: 4054

28th Nov 2008 11:05 am

GraemeS

Member Since: 17 Mar 2008
Location: NSW
Posts: 706

2010 Discovery 4 3.0 TDV6 SE Auto Nara Bronze

countrywide wrote:
This a long shot as I have no idea on how the suspension works, but from what I can see the height sensors are probably some sort of measurement based on resistance (bit like a potentiometer). Would it not be possible to wire in a second value which could be switched in to vary this value depending on whether you wanted to higher or lower the suspension. It would act like a shortened rod and you could just switch out the circuit via a dash switch. Obviously it would need to be calibrated to make sure it worked, but you could do this with a trimmer.

Of course all this is based on the level sensors being resisitive, so if they are not I am talking rubbish. Also if it were that easy I guess everybody would have done it by now.

You are correct - they are just single track potentiometers with the signal being the result of voltage-dividing 5V. I reckon I can make such a unit, controlled by a microprocessor that would reset to std values if the voltages get close to operating limits. The biggest obstacle would be finding M&F connectors for the suspension ecu (C0867 & C2321) to make it plug and play. However I can't do the R&D for some time as my D3 acquisition wont occur for at least 12 months. I have a device ready for testing that automatically operates the RAISE switch when the vehicle slows enough for off-road height to be selected after having attained the speed to cause the suspension to raise, purely as a way of not forgetting to hit the switch when approaching washouts etc.

26th Dec 2008 1:02 pm

GraemeS

Member Since: 17 Mar 2008
Location: NSW
Posts: 706

Further to my above post...

1. Can anyone provide the resistance across a sensor 5V and ground pins? This is for the sensor itself and disconnected from the wiring loom.
2. Can anyone provide a typical sensor signal voltage (eg 1 sensor but more is better) at both normal height and off-road height? This would most likely have to be measured at the appropriate suspension ecu plug behind the driver's footwell side cover. The ignition must be on. I can provide connector pin and wire colour if required.

These values are all I need to build a prototype unit that would need to have 5 wires soldered to existing wires at the suspension ecu, in the absence of M&F connectors to avoid soldering. The current design has the system enabled and disabled by a momentary switch with a status LED. It would revert to original access, crawl and super-extended heights even whilst enabled, with the LED flashing at these times.

Thanks if someone can help.

27th Dec 2008 4:40 am

phurley

Member Since: 19 Aug 2007
Location: So. NH
Posts: 175

Resistance across +5V to ground (pins 1 & 5) on height sensor is 1.618kohms for part #RQH5000042 (right rear sensor, I think...). Resistance range across signal to ground (pins 4 & 5) is 1.081 ~ 2.59 kohms. These are bench measurements - part is sitting on my desk. Note that at the low end, resistance increased then spiked into the Mohms before going no-contact.

Within the next couple of days, I'll take some voltage measurements at the air suspension control module. I'll also double check that supply and ground readings are the same for each sensor.

I just want to double check with you that the circuit you're designing is self-calibrating, ie. that you're accounting for the variance of each sensor signal voltage even when at-rest and "normal" height. Presumably, since the LR height calibration procedure does not require going into "off-road" height, you're relying on the soon-to-be-known linear, fixed resistance ramp which you will utilize to simulate each individual sensor, yes?

31st Dec 2008 3:00 am

caverD3

Member Since: 03 Jul 2006
Location: Oberon, NSW
Posts: 6922

I think you will need to vary each sensor by altering the output by the same amount as ech corner self levels on its own.

My system is now air tight.
Got final bill from actuator supplier. Looks like it will not retail for under $1000.

However it comes with Nito connector for air hose, so you don't need to buy a compressor.

â€œThere are only three sports: bullfighting, motor racing, and mountaineering; all the rest are merely gamesâ€
Ernest Hemmingway
D4 3.0 Active Diff, Adaptive Lights, High Beam Assist, Surround Cameras, Privacy Glass.
D3 2.7:Adaptive Headlights,Electronic Rear Diff,ARB Bar,Blaupunkt Speakers,JVC Powered Subwoofer,Removable Snorkel,Mitch Hitch,Pioneer After Market Head Unit,Steering Wheel Control Adaptor,Remote Adjustable Supension Rod System, Taxside Dual Battery System.

31st Dec 2008 3:31 am

phurley

Member Since: 19 Aug 2007
Location: So. NH
Posts: 175

"..vary each sensor by altering the output by the same amount ..." -- exactly!

For example, hypothetical measurements before & after of properly modified circuit (for same actual height - of course I realize that the whole point would be that the system would pump each damper until the "tampered" value reached the original value it was expecting, ie. 2.32V for LF sensor below).
Original "Tampered"
LF 2.32V 2.14V
RF 2.30V 2.12V
LR 2.35V 2.17V
..etc..

I just want to make sure it wasn't coming like this...
Original "Tampered"
LF 2.32V 2.14V
RF 2.30V 2.14V
LR 2.35V 2.14V
..etc..

31st Dec 2008 4:06 am

GraemeS

Member Since: 17 Mar 2008
Location: NSW
Posts: 706

Hi Phurley.

Thanks for the info.

I need the total resistance pins 1-5, so thanks. I know that one sensor is used on the RF & RR and a different one on LF & LR, and the fronts are upside down compared with the rears, and that is quite significant to me.

I need to establish whether the front and rear raise by the same approximate voltage, as pictures of the super-extended height seem to show the rear higher than the front, but that may not be the case. I would be increasing/decreasing the voltage at least in axle pairs by adjusting resistors, not by supplying a fixed or common voltage. This will increase the load on the 5V supplies (which I will calculate) but so far it appears to be by a rather insignificant amount.

I may get access to a vehicle later in January. I planned to get the sensor signal voltage of all 4 sensors at normal height (door open to stabilise) then again at off-road height (then door open again) to determine whether the voltage increases or decreases and by how much at each sensor. I will then be able to calculate the adjusting resistor value(s) and use appropriate components to connect/disconnect them.

If you can get voltage readings and I also get some from another vehicle, I may make a better initial calculation for a trial.

I also plan to include the facility to automatically send a RAISE request once speed gets low enough for the system to accept it, although this facility could not be activated if the RAISED RIDE HEIGHT function was active, purely for safety reasons.

Thanks again.

Edit: I will not be limiting the actual height to try to prevent over-extending the bags or to give standard access & crawl heights as the process would not be sufficiently rugged to always work, with the liklihood of lowering at the worst possible times. Hence the driver would just have to disable the function to allow proper heights when required.

31st Dec 2008 12:48 pm

GraemeS

Member Since: 17 Mar 2008
Location: NSW
Posts: 706

phurley wrote:
Resistance range across signal to ground (pins 4 & 5) is 1.081 ~ 2.59 kohms.

I had assumed the 2.59K was due to poor/contaminated contact with the track, as the swept range would be within the total resistance of 1.618K for a simple potentiometer. Can you confirm this is the cause?
Thanks.

31st Dec 2008 8:37 pm

phurley

Member Since: 19 Aug 2007
Location: So. NH
Posts: 175

No, that's the stable contact range on the bench. Link arm swings 360Â° when not attached to vehicle and track contact is maybe 130Â°. Of course, on the vehicle the link arm probably only articulates 50Â° at most.

When I take signal readings, I'll also take resistance readings as well (from ecu plugs), and just make a matrix of all the values, ok?

31st Dec 2008 9:01 pm

GraemeS

Member Since: 17 Mar 2008
Location: NSW
Posts: 706

phurley wrote:
No, that's the stable contact range on the bench. Link arm swings 360Â° when not attached to vehicle and track contact is maybe 130Â°. Of course, on the vehicle the link arm probably only articulates 50Â° at most.

When I take signal readings, I'll also take resistance readings as well (from ecu plugs), and just make a matrix of all the values, ok?

Hmm, I'll have to think about the range values some more. The matrix wouldbe very helpful.
Thanks.

31st Dec 2008 10:51 pm

GraemeS

Member Since: 17 Mar 2008
Location: NSW
Posts: 706

OK, there must be a 1K resistor between pin4 and the track contact. This may or may not affect the amount of extra height at other height setitngs.

31st Dec 2008 11:06 pm

GraemeS

Member Since: 17 Mar 2008
Location: NSW
Posts: 706

Actually, that 1K resistor presents a problem. It will be there to limit the current available to the ecu, but wont affect the voltage. I need to get access before that resistor, ie inside the sensor, so maybe my idea is a no-go. I'll have to give the project some more thought.

Maybe I'll end-up just being able to provide the auto-raise. More think time is required.

31st Dec 2008 11:44 pm

GraemeS

Member Since: 17 Mar 2008
Location: NSW
Posts: 706

I can continue with the project as the 1K in-line resistor doesn't really affect my plan. I don't require any more resistance readings, just the 4 sensor signal voltages at the ecu for both normal and off-road heights. No voltage measurements are req'd for the sensor inputs and the aforementioned increase in current draw by the sensors will no longer apply.

1st Jan 2009 4:06 am