Member Since: 29 Apr 2018
Location: Nova Scotia
Posts: 46
DSC on sweeping turns
Good day,
For a while now I have been having an issue where DSC kicks in on sweeping turns on more twisty roads. Initially this was only happening on lefts but has also started happening on rights. I've read through many of the threads on this but am unable to solve the issue thus far.
Prior to the first occurrence I had made a maneuver getting around a gate on a logging road that required a turn to full left lock. While no issue was apparent in the next dozen km or so, after stopping for a while and heading back home on the roadway, I first encountered the DSC kicking in on sweeping lefts at speed. A day later as soon as I would take any sharp left onto a road/out of a driveway, HDC fault, dropped to bumpstop etc. This would go a way and would go back to normal height after shutting down and starting up until the next sharp left. Fault code with the gap indicated faulty front left wheel speed sensor. Had this replaced at a shop and suspension issues went away but the DSC on sweeping lefts at speed continued and have also been happening now on some rights.
A year + later I am still chasing this gremlin. Tire pressures have been confirmed, alignment done, steering angle sensor collar is fine. Had the dealer look it over asking that they look at bushings, links etc. They say all is fine but could not recreate the problem as roads in the city do not have the long curves required to trigger it. Local garage was able to replicate but where not able to determine the issue. Have since also replace the front/rear sway bar bushings and front sway bar links which were shot( dealer never noticed the link issue so question how hard they looked at the vehicle)
Last couple days have been looking at live values. Wheel speed sensors seem to be fine as does steering angle. A couple items got my attention and seem off.
On any left the yaw rate seems to be fine going from 0 on a straight to 145 deg/s or so depending how much of a turn. However with any right input yaw rate starts at 65500 deg/s and goes down to 65400 or so depending how much of a turn. Not familiar with usual reading but I expected to see either a negative number like the steering wheel angle or a similar positive like on left input.
I did an additional reading looking at yaw rate, lateral accelerometer and longitudinal accelerometer. Interestingly this showed the Lat/long displaying readings in the 65K range on left turns and "normal" readings on right turns.
The graph from the log shows the 65K spikes on yaw/lat/long the whole drive as steering input went left to right.
Click image to enlarge
Perhaps related or not, perhaps even normal, I had also viewed the gallery pressure and notice it seemed low, it was sitting around 174kPa when driving. Later I went back and plugged in gap to take some readings. With a cold vehicle the Gallery pressure was sitting at 125kPa.
I started the vehicle. There was no change to the gallery pressure and the compressor didn't kick in at the time. I selected off road height, the vehicle raised compressor kicked in and brought it up to about 1780kPa, compressor temp went from 15c-33c. As soon as the compressor stopped, I hear a release of air and the gallery pressure plummeted back down to about 145kPa. I dropped back to normal height and recorded it the second time. Same thing happened after selecting off road height, compressor started, pressure increase to 1780kPa, temp went from 30-50c. As soon as the compressor cut out, release of air, pressure plummets. Selected normal height, compressor stays off pressure spikes to around 600kPa then settles down near 200.
Click image to enlarge
I have not noticed any suspension issues, vehicle holds its height overnight and even if sitting a week only minor adjustment on startup, no sagging. Have not had any issues moving between height settings, reservoir was replaced 1.5 years ago. AMK compressor installed by previous owner expect via dealer. No fault codes related to suspension, compressor etc.
Booked into a local shop next week for another stab at the DSC issue. Curious if any of the above information is relevant to help point them in a direction.
Ryan R
18th Mar 2023 11:50 pm
BradC
Member Since: 29 Apr 2019
Location: Perth
Posts: 118
That gallery pressure behaviour is normal. As soon as the suspension has finished "doing stuff" it vents the gallery to ensure next compressor start isn't into a big head. Nothing unusual there.
19th Mar 2023 2:51 am
Naki Blake
Member Since: 31 Dec 2021
Location: Taranaki
Posts: 241
I had my DSC activating when driving around tight corners at open road speeds. I used my GAP IID tool to lower the ride height by 10mm and it hasn't activated since. I know its not fixing the root cause, I'm suspecting wheel height sensor calibration is required or one of the sensors is crook, but hasn't bothered me since, one year on.
Cheers Blake
19th Mar 2023 8:16 am
LittleG
Member Since: 21 Sep 2013
Location: Wombourne
Posts: 389
How old are the tyres? Had a similar situation to yours which was resolved with new tyres fitted. My original tyres had plenty of tread left and appeared to be in good condition, no signs of sidewall perishing. Can’t remember the age but they were a few years old.
19th Mar 2023 8:26 am
L319
Member Since: 14 Dec 2013
Location: Herefordshire
Posts: 2080
I can only say that the four times I have had this issue it was the steering angle sensor loose on its shaft
19th Mar 2023 9:49 am
RyanR
Member Since: 29 Apr 2018
Location: Nova Scotia
Posts: 46
BradC - Thanks for confirming normal ops on the gallery pressure.
Naki - I will see about doing a ride height calibration to see if that has any effect. I've yet to try one myself but will look up the process with the Gap. Done once at the dealer but that may have been a visit prior to this problem. I had taken a couple screen grabs while looking at that yesterday.
LittleG - I have thought about the tires. Believe they may be 5 years old and have 40K km on them. Nokian WR3's. Still have tread, have noticed a little cracking on the sidewalls. Is one item I am having the garage look at as I am considering more of an A/T tire for the occasional abuse I give them.
L319 - I will crawl under the dash and have another look at the yellow collar on the steering shaft to see if I can detect any play. During one of the garage visits to try and rectify the issue I had given them the "how to" about gluing it in place as a preventative measure but honestly never looked again to confirm if they actually did or not. Live values of the steering wheel angle did not seem out of place.
Good start on a few items to check out. Thanks!
19th Mar 2023 10:23 am
RyanR
Member Since: 29 Apr 2018
Location: Nova Scotia
Posts: 46
Did some troubleshooting today.
Calibrated the steering angle sensor, no change to the DSC kicking in. Angle may have been off by 2-3 degrees but hard to tell as it doesn't take much steering wheel movement for it to swing either direction by a few more without noticeable change at the tires. Checked out the yellow collar on the steering shaft. It appears to move with the wheel turn without any slipping, held a finger on it and seems to be solid on the shaft.
Did the guided suspension calibration on the GAP several times. Again no change to the DCS kicking in. Original measurements had FL 15mm under, FR 12mm under, RR 5mm over, RL 12mm under. I ran the calibration a few times. For some reason even after calibrating the fronts to 466 after cycling to off road and back to normal after completion they rested around 460mm. On the last calibration I set them a little higher around 471 when making the adjustments and they held closer to 465 after that. Normal to need to tweak the height a little to get them to stay at spec?
I think I have ruled out height sensors and steering angle sensor as the culprit. Hopefully the garage has more success than I. Will have them go over all the bushings, inner/outer tie rods and have a good look at the tires. If there are any other suggestions let me know and I will investigate.
20th Mar 2023 10:54 pm
Breg90
Member Since: 04 Feb 2017
Location: Falkirk
Posts: 349
Mine does this - its an unmatched tire. Even though its the same 'size'. Try borrowing a different set of tires from some one and going for a quick drive to rule it in/out.
I live with it as the tires still have good tread....
One way to check the rolling radius of your tires are equal:
1/. Park some where level with about 50m of straight road.
2/. Put chalk marks at the bottom of each tire
3/. drive 20 - 30 M in straight line.
4/. If the rolling radius of your tires are the same the chalk marks should all be at the same angle/position around the tire.
AdrianSeries one 1949 - in bits, chassis is strapped to the ceiling in my garage (beside the canoe)
LR 90 - In bits
Disco 3 - currently in bits
21st Mar 2023 1:15 am
M3DPO
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8124
Check tyre pressures, swap wheels front to back diagonally if not uni-direction tyres.It can when others can't,
It will when others won't,
It goes where others don't.
21st Mar 2023 8:48 am
rrhool
Member Since: 28 Aug 2014
Location: Norfolk
Posts: 4410
Mine does this on a specific corner in the road near where I live. If the road is slightly damp, it'll trip the DSC every time. My tyres are all the same, pressures are correct, tracking is right, no suspension issues, steering sensor cal is right. I put it down to the calibration of the system.
Because it also takes info from the yaw rate sensor and lateral g sensor, I think certain road profiles will trick the system into thinking there is a loss of traction.
The road that trips mine, is a 40mph road with a 90deg corner and it is fairly banked, so the corner is still safely navigated at 40mph. at 38mph no problem, at 40 or above DCS kicks in.Richard
D3 SE 2007. Triumph 2.5Pi 1973. Ferguson TEA20 1948.
Discovery 2 4.0 ES 2001- Gone
Discovery 1 300Tdi ES '95 - Gone
Range Rover Classic '79 - Gone
Are you sure it's not the steering angle sensor that is loose, or at least not turning correctly with the steering column. I had a fairly intermittent and inconsistent problem with the DSC activating while cornering at normal (meaning appropriate for the corner) speeds. Sometimes it would be turning left, sometimes to the right, often not at all, but tracked down quickly by Steve Norman to a loose steering angle sensor which he said was not uncommon. This was quite a few years ago on a low mileage D3. He fixed the old sensor by epoxing back to the steering column I think and its been ok ever since, certainly more than 10years since the repair.
28th Mar 2023 11:49 pm
RyanR
Member Since: 29 Apr 2018
Location: Nova Scotia
Posts: 46
The yellow collar seems to be firmly in place so I am not suspecting that at this time. Truck went to the garage and they have found one of the upper rear control arms has a lot of play in the bushings and the other side appears to be on its way out to. New arms have been ordered so hopefully will be able to confirm if that was the issue once installed. Held up though as it has been noted the transmission oil cooler lines are leaking so need to get that sorted first, used set in coming in but shipping will be a while. Will update in the end if the problem gets solved with the upper arms.
29th Mar 2023 1:08 am
RyanR
Member Since: 29 Apr 2018
Location: Nova Scotia
Posts: 46
Just to update. After 2 years of dealing with the DSC kicking in, it is finally sorted. Drove a twisty road yesterday that was previously setting it off. Both rear upper wishbones have been replaced as they both had a lot of play in the bushing. Tires also changed out to a set of Toyo Open Country AT3.
26th Apr 2023 10:53 pm
John P
Member Since: 12 Aug 2011
Location: West Sussex
Posts: 1275
That's good news.
27th Apr 2023 10:56 am
Motolab
Member Since: 18 Oct 2019
Location: Sleen
Posts: 1820
RyanR wrote:
Just to update. After 2 years of dealing with the DSC kicking in, it is finally sorted. Drove a twisty road yesterday that was previously setting it off. Both rear upper wishbones have been replaced as they both had a lot of play in the bushing. Tires also changed out to a set of Toyo Open Country AT3.
I had the same positive experience after replacing all the controlarms on my D3
Worth every quid (and it was a few quid) feels like a new motor now…
I have a reasonable low mileage D3, but it is still 16 years old. Rubber does age and then wear often goes quickBest regards
Harold
Always looking for Pre '55's & Pre war British Motorcycles! knowing or having one for sale? PM please. I visit the UK 6 times a year
Ps. I edit my texts quite often, english is not my native language, so I will edit My “typo’s” etc.
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