This weekend I was driving along muddy ruts and had the terrain response set to, umm, 'mud and ruts'! Every now and then bits of more solid ground crossed the ruts and as soon as the front wheels hit these the car slammed to a halt, Apart from being uncomfortable, it killed-off momentum/progress.

Can anyone think of a way round this or a different setting that would be just as effective but without the slamming (possibly just 'normal')?

Cheers,

Hugh

Try disabling HDC or if your car has auto TR2 leaving the TR in auto mode 2020 Pangea Green 1st Edition D240 New Defender 110 is here and loving it
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Also in my garage is a 1996 TDi300 Defender 90 County HT made into a fake CSW

I don’t understand what you mean by slammed to a halt? When you let off the throttle? Sounds as though HDC was engaging as it automatically selects it when setting mud and ruts 2003 BMW M5 - 5 Litres of V8 Optimax Slurping Goodness in Carbon Black

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It will not be HDC as it is speed related not surface condition related. Oh what is "auto TR2" - never heard of that in an early RRS.

Most likely it is Dynamic Stability Control (DSC) activating (the DSC switch above the radio). It will apply the brakes and cut engine power if any sideways movement is detected as might happen when the front grips a firmer surface.

DSC should be switched off when ever offroading and note it reactivates with each TR change so needs to be switched off with each TR change and needs to be constantly checked.

Garry 07MY RRS TDV6
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TR2 and AutoTR2 are what is fitted to L494 RRS - TR2 pre 2015, Auto TR2 after ( yes I see the oP has a 2006 MY now!) The auto system is just that, the computers decide which mode Terrain response should be in rather that the driver and it refreshes the mode every 30secs to,a minute,IIRC, without disengaging the mode you were in. The auto mode is very good but I still prefer to choose which mode the system is in rather than have messages flashing across the satnav and TFT Dash advising that the “system is recalibrating” at frequent intervals

Agree that it could be the dynamic Stability Control, but then there would have to be other inputs like see-sawing to the steering wheel, heavy on/off the throttle and/or brakes to make it cut in because it is trying to prevent and accident on road

I wonder if HughN has the set in Speed for the HDC set very low, below 5mph as it is variable with the cruise control + and - buttons 2020 Pangea Green 1st Edition D240 New Defender 110 is here and loving it
2018 Melting Silver Mini Countryman PHEV - soon to be replaced
2015MY Corris Grey SDv6 HSE Dynamic, the best car I have ever owned, totally reliable only a cou0le of rattles in 3 years, now no longer in my care
Also in my garage is a 1996 TDi300 Defender 90 County HT made into a fake CSW

I think we need more info from HughN first. 2003 BMW M5 - 5 Litres of V8 Optimax Slurping Goodness in Carbon Black

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Thanks chaps.

The car was travelling in a straight line and I didn't notice any sideways movement. I had it moving at a constant speed and constant throttle and it was happy until the front wheels contacted a drier solid bit, at which point it was as if the brakes had been slammed on - the car slowed abruptly and the front wheels skidded/slid on the drier ground as if they had locked-up. As soon as it had stopped, it started moving again - until the next solid bit.

It sounds like I need to read about HDC in the manual. TBH, even though its been fitted in a few LR I've owned, I've never used actively engaged it - low ratio, low gear and a foot hovering slightly above the throttle has always done me.

I'll see if the dashcam captured it...

HDC is activated automatically in Mud & Ruts. It wouldn't normally bring to a stand still though as the minimum control speed is above 0mph. I wonder if the centre diff was locked at the point you got to the firm ground. If both axles were slipping slightly and the centre diff was locked, as the fronts found grip, it might have caused the DSC to kick in.

One thing with clever systems like LR use is that occasionally they do unexpected things. 2012 SDV6 - it's missing a couple of cylinders
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I've never had that issue with mine using mud/ruts.

No, neither have I but I'm just "thinking aloud".

I do also wonder if the hard bit of ground was raised slightly compared to the ruts and acted like a sleeping policeman. If the revs were only just enough for slow progress in the ruts, hitting a lump can be enough, momentarily, to halt progress. 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

I suspect it's the HTC kicking in, did it make a horrible grinding noise when you were stopping?

That's interesting advice about turning off the DSC, how does that interact with the special programs? I thought it just turned off the active anti roll bars.

Quote:

I'll see if the dashcam captured it...

Nope

d-9 wrote:

That's interesting advice about turning off the DSC, how does that interact with the special programs? I thought it just turned off the active anti roll bars.

d-9 wrote:

...did it make a horrible grinding noise when you were stopping?

It certainly did.

HDC then.

I usually turn off HDC when on reasonably level ground. I find it more annoying than useful in such situations - as you appear to have found. It's excellent on steep, long descents or in icy conditions where it slows you nicely without any skidding. In more "normal" off road situations, I find low range, first gear is usually all that's required to hold the speed down on a descent. A short, steep, descent on a slippery surface - wet mud over firm ground, for example - is also a good place to have it switched on.

The thing with HDC is to set it up to your desired speed whilst on the level. Then when you go over the brow in to the descent, the vehicle doesn't "run away" until it hits the default HDC threshold. Madly pressing the cruise buttons to reduce the HDC threshold speed midway down a slope is, erm, attention grabbing! As said, low range first gear often keeps one going slowly enough that HDC doesn't need to kick in. 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed