DISCO3.CO.UK - View topic - Still DSC activation problem

alinton

Member Since: 06 Feb 2006
Location: Waterford, Ireland.
Posts: 108

2006 Discovery 3 TDV6 S Auto Bonatti Grey

Still DSC activation problem

Hey all, some weeks ago I posted about my problem with the DSC activating when I go round bends at about 60mph. Got some suggestions.

My indie LR mechanic (after the dealer said 'they didn't know what the problem was') has changed ball-joints that he found were worn, two reaction arms and ARB bushes. He also found a fault with the steering position sensor which he replaced.

But after all this, and after getting the car 4-wheel tracked, the problem remains!

Symptoms are, as I steer round a moderately hard bend at 50-60mph, the DSC activates, light comes on, etc. It happens more on a right hand bend than a left.

ANY suggestions at this stage would be EXTREMELY welcome!

Thanks

Andy.

4th Apr 2009 6:12 pm

caverD3

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

2012 Discovery 4 3.0 SDV6 SE Auto Fuji White

Could be wheel speed sensor related. I assumed from what you said that they have replaced the supension sensors. Could be a bad connection in either. 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.

4th Apr 2009 11:17 pm

Disco_Mikey

Member Since: 29 May 2007
Location: Dundee, Scotland
Posts: 20727

2005 Discovery 3 TDV6 HSE Auto Cairns Blue

Re: Still DSC activation problem

alinton wrote:

Symptoms are, as I steer round a moderately hard bend at 50-60mph, the DSC activates, light comes on, etc. It happens more on a right hand bend than a left.

ANY suggestions at this stage would be EXTREMELY welcome!

A moderatly hard bend @ 60mph? Surely that is the problem... Does it still do it if you go around the corner slower?

The DSC system can be quite sensitive. You can activate it by just rocking the steering at 60-70mph in a straight line... My D3 Build Thread

TDV8 Retrofit Build Thread

5th Apr 2009 7:04 am

alinton

Member Since: 06 Feb 2006
Location: Waterford, Ireland.
Posts: 108

Re: Still DSC activation problem

A moderatly hard bend @ 60mph? Surely that is the problem... Does it still do it if you go around the corner slower?

The DSC system can be quite sensitive. You can activate it by just rocking the steering at 60-70mph in a straight line...[/quote]

No it doesn't. But I can't expected to slow to 40mph every time I go round a corner. And it never used to do it!

(so there can't be much wrong!

)

A.

5th Apr 2009 6:46 pm

stapldm

Member Since: 11 Sep 2006
Location: Swine Town
Posts: 2330

2007 Discovery 3 TDV6 HSE Auto Stornoway Grey

In the absence of any of our real genius' adding anything new, thought I'd just look at your problem from a different perspective and then ~~guess~~ figure out what sensors are possibly at play.

During hard cornering, the following forces are going to be present. I'll assume a right hand bend for the observations; reverse for left hand bends.

Left hand suspension tower under extra compression       Right hand suspension tower under lower compression

Left hand wishbone assembly under compression            Right hand wishbone assembly under tension

Left hand tyre is under extra compression                Right hand tyre is under lower compression

(Creates smaller effective rolling diameter)             (Creates larger effective rolling diameter)

Left hand wheel is turning marginally faster             Right hand wheel is turning marginally slower

Solid State gyro shows centre of gravity has moved to the left of the car (I assume this part of the SRS or GPS system data is fed to the car for other purposes)

Steering wheel position sensor shows wheel is turned to right

I'd welcome any further input to confirm/dismiss my assumptions, but I'd guess at two main sets of sensors at the top of any issue list:
Wheel speed sensors (could falsely indicate loss of traction and cause DSC)
Wheel height sensors (could falsely indicate 'rollover' and cause DSC)

Other sensors that may be coming into play:
Air suspension pressure sensors in each turrett.
SRS/GPS solid state gyro is duff (if it is used)

Are the tyres definitely at the right pressures? Lower pressures could exacerbate any of these symptoms and push the sensor data past the thresholds for DSC. If it only happens for turning one direction, maybe swap the tyres over and see if the issue moves to the opposite direction of turn (is swapping tyres across axles safe?)

I'd think your best bet for resolution would be to get 10forcash sitting in the passenger seat with his box of tricks monitoring the car whilst you did your cornering. I've seen video of him hanging off the side of a mountain whilst spotting for a D3 that was 6" wider than the icy track it was driving so I know he's brave enough

That's it, brain is empty of further ideas, I hope that kicks off some thoughts by more knowledgeable members of the forum.

Edit : When I ask about correct tyre pressures, I mean by using a real gauge and not one of those random number generators on a petrol station forecourt. Dr. Ian Malcolm:
"Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should."
Transgenic tomato anyone?

5th Apr 2009 8:27 pm

alinton

Member Since: 06 Feb 2006
Location: Waterford, Ireland.
Posts: 108

That's very helpful, thanks.

I'll persue those avenues, as it sounds reasonable.

Cheers

Andy.

5th Apr 2009 8:33 pm

bkehoe

Member Since: 25 Feb 2006
Location: Wexford
Posts: 1481

2005 Discovery 3 TDV6 HSE Auto Zambezi Silver

I can provide an independent observation that it isn't andys habit of excess speed that induces this

I drove his d3 today and got the dsc activating in a mild right hand bend at 70kph - a bend you'd happily take at 100K+ safely normally.
Oh and I've never ever seen the DSC on mine activate while on-road

IE - 05 D3 TDV6 HSE - Zambezi Silver
SA - 07 VW Golf TDI - White - Sold!

6th Apr 2009 7:44 pm

GaryEss

Member Since: 27 Apr 2009
Location: midlands
Posts: 42

don't know if you have fixed this yet, but just a few pointers.
DSC is not too sophisticated - it's only really concerned with yaw rate (sensor under centre console) and steering angle (Sensor on column). It's main function is to quell unwanted oversteer or understeer. It does this by using the ABS system to individually brake one wheel on one side only (on the rear to control understeer, on the front to control oversteer).
It looks at steering angle and rate, "decides" where the driver is attempting to go and if the yaw rate of the vehicle does not concur it will brake the wheel on one side to "pull" the vehicle toward the desired direction. In extreme case DSC will also limit engine torque output.
The same warning light in the IPK will also illuminate when the the traction control is active. This is different to DSC (though the function is integrated into the same control unit). This looks for differences in wheel speed. Up to a certain speed it will brake the spinning wheel to maintain grip- no doubt you may have seen this during off road excursions. Over a certain speed threshold it will limit engine torque only (no wheel braking)when wheel speed differences are detected.
Does your car have the same size , make and load rated tyres all round? Can you try a substitute set and retest? Any difference in rolling radius can cause the VDM to falsely operate especially during cornering.
If these are all correct and identical then check the vehicle history. If the Steering angle sensor has been calibrated with the column turned off centre or if a significant adjustment to the geometry has been needed then it may require re calibaration again.
Sorry cannot help much more.

27th Apr 2009 4:21 pm

alinton

Member Since: 06 Feb 2006
Location: Waterford, Ireland.
Posts: 108

On the contrary, very useful, thanks.

It seems my steering position sensor was actually faulty; Its changed now and on the way home the car behaved fine.

My only remaining niggle is that the castor on the nearside front wheel is out of tol, and the local crowd with the computerised tracking system "don't do" castor.

What's Castor anyway?

Oh, and the same wheel needs a new bearing.

Everything's fine apart from that!

Andy.

27th Apr 2009 8:26 pm

wiggs

Member Since: 03 Sep 2006
Location: Manchester
Posts: 14368

2015 Discovery 4 3.0 SDV6 HSE Auto Fuji White

Click image to enlarge

Some info http://www.disco3.co.uk/gallery/albums/use...gnment.pdf

and here http://www.familycar.com/alignment.htm G4 Gone ...but not forgotten

27th Apr 2009 8:41 pm

caverD3

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

You are better going to the dealer. They will put it into geometry set mode before getting it aligned. Have a full tank of juice too. 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 Apr 2009 1:36 am

Bushwanderer

Member Since: 27 Nov 2007
Location: Northern Rivers, NSW, Australia
Posts: 2050

2005 Discovery 3 TDV6 S Manual Buckingham Blue

Don't forget to get the bearing replaced first. The Bearded Dragon

28th Apr 2009 1:50 am

alinton

Member Since: 06 Feb 2006
Location: Waterford, Ireland.
Posts: 108

My local dealer is useless. If they were any good they'd have noticed the bearing and the several badly worn ball-joints and ARB bushes the last time they serviced it, but they didn't.

As I said before, they said they 'didn't know what was wrong, as the computer showed no faults'.

"Computer says Nooo".

The car is out of warranty now, and I don't ever intend to give the car to them again.

A.

28th Apr 2009 2:07 am

caverD3

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

You could get BBS Spys kit and put it into the mode yourself.

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 Apr 2009 2:15 am

Synthdr

Member Since: 26 Feb 2013
Location: near coventry
Posts: 20

2005 Discovery 3 TDV6 S Manual Java Black

Hello I have been reading your thread my disco3 had a bump in the Jan snow the garage replaced the steering rack and some suspension components I am now having the same fault as you with the garage just blaming my driving. I have had my steering angle sensor changed but still have the fault does any on have any ideas. When the garage checked today after we went out and got dsc to come on the car had no faults recorded with any sensors when we got back to the garage and they plugged the car in, the car never did this before the accident and I am at my wits end I cant afford to replace and dont feel safe in the car as it is, the garage seem unable to help they got paid by insurance.

Parts changed by garage after accident on the drivers side of the vehicle.
lower trailing arm, ball joint, steering rack, wishbone, bearing & hub, steering angle sensor. recalibrated steering alignment. the steering rack was only part visibly damaged the rest were done on safety grounds

At the last MOT the trailing arms were both replaced so they are of comparable age and ball joint the wishbone is the only old part on the passenger side with all new on drivers they say this makes no diference the car is a 55 reg. Thanks for any help or suggestions, from a bedraggled D3 owner Sam

26th Feb 2013 4:35 pm