Member Since: 27 May 2011
Location: Sticking the Ex back in the skanks bin
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The only thing you can do is studs or socks in such conditions. Unless fresh snow falls then you can use that to get some grip on top of the ice but still a death trap!
I've used waffles recently to help in really bad snow though FFRR Owner, very nearly became a D3 owner
Test piloted a new D4 XS SDV6.. Gone and being forgotten i hope!!
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2nd Jan 2015 1:46 am
LHD
Member Since: 05 Apr 2006
Location: Lugano area
Posts: 689
I've seen the case twice in 10 years where in Zurich it has snowed in the afternoon and then immediately melted. And then within 30 minutes, frozen again. Apart from the snow was now about 2" of ice on all surfaces.
Cars would not be able to drive on it and there are usually many accidents. And this is where everyone has winter tyres.
Cars will, for instance, come to rest on the kerbs when stopping due to the camber of the road.
The first time it happened, I walked a mile to the tram stop which would get me to work......a tram line not shared with buses so it was actually functioning.
Given the weather in Zurich now, I'm not shocked that cars can move when not required If you're parking on a slope, use the kerb to keep your Disco still.Discovery 3 Manual as PDF | Blackvue 500 | BAS Remap | Mates did South America in a Landie
2nd Jan 2015 7:14 am
DG Site Moderator
Member Since: 12 Dec 2005
Location: The Gaff
Posts: 50968
Robbie wrote:
If the transfer box is in low range when the EPB is applied then the brakes are applied with additional force.
Can't find any reference to this being the case on the D4 Rob ...the operating modes appear the same for high and low ...the only time that additional force is applied is when "dynamic apply" mode is activated i.e. when you pull up the lever over 6.25mph...then of course it activates the ABS module to apply full braking to all wheels. 21 year LR veteran > D2 GS 2003 > D3 S 2006 > D3 HSE 2009 > D4 HSE 2013 > D4 HSE 2015 > D5 HSE 2018 > DS HSE R-Dynamic P300e 2021
2nd Jan 2015 9:25 am
Robbie
Member Since: 05 Feb 2006
Location: ¯\_(ツ)_/¯
Posts: 17932
Interesting. The Topix writers could do with including the details of the HIGH/LOW range effect on the EPB.
In case JLR are reading this…
The EPB has a set of tension values sensed via the force sensor on the splined shaft (these are the 2 bits that come apart when you pull the emergency cable). The higher set of values is used when LOW is selected and the lower set is used when the box is in the HIGH range. These values are also used for the automatic load adjustment which monitors the force applied to the EPB for up to 30 minutes after 'ignition off' to stop heat soak from slackening the force applied.
For those with Drive Away Release (DAR) enabled when HIGH range is selected the EPB tension is released slightly to reduce the overall release time and provide a smoother drive-away. This coordinated tension release is prohibited when LOW range is selected in order to prevent vehicle movement. As such the DAR is rather sudden when in LOW range - this is not a fault. Incidentally the reduced / smoother release is disabled in HIGH range if the 'Failsafe' tighten has operated since the last ignition cycle. This will also lead to a rather jerky DAR experience.
One of the practical upshots of this is by selecting LOW range you can check your EPB under higher loads (squeal check) and adjust accordingly.
Land Rover - Turning Drivers into Mechanics Since 1948
Member Since: 12 Dec 2005
Location: The Gaff
Posts: 50968
May have changed for the D4 to simplify perhaps ? ...and the monitoring is only for 20 mins it seems ...but here you go
Quote:
Sleep Mode
To reduce quiescent drain on the vehicle battery, the parking brake module incorporates a sleep mode. The parking brake module enters the sleep mode, provided the ignition is off and there are no signals from the wheel speed sensors, when one of the following occurs:
20 minutes elapse after the last actuation of the parking brake.
If no actuation occurred, 20 minutes elapse after the ignition is switched off.
The parking brake module wakes up from the sleep mode when on of the following occurs:
An apply or release request is made with the parking brake switch.
The ignition is switched on.
A key out apply is activated.
The parking brake module wakes up within 500 ms. The high speed CAN bus is activated within 200 ms maximum.
When the parking brake module is woken with a release request from the parking brake switch, the parking brake module ignores the request but illuminates the red brake warning indicator. The parking brake module extinguishes the red brake warning indicator and goes back to sleep immediately the switch is released to the neutral position.
When the parking brake module is woken with an apply request from the parking brake switch, if the parking brake is already applied the parking brake module ignores the request but illuminates the red brake warning indicator. The parking brake module extinguishes the red brake warning indicator and goes back to sleep immediately the switch is released to the neutral position. If the parking brake is in the released condition when the apply request is made, the parking brake module illuminates the red brake warning indicator and applies the parking brake. The parking brake module extinguishes the red brake warning indicator and goes back to sleep 3 minutes after the apply activation, or immediately after the switch is released to the neutral position, whichever occurs last.
Dynamic Apply
In the dynamic apply mode, if the vehicle speed is more than 10 km/h (6.25 mph) when the parking brake switch is selected to apply, the parking brake module requests the ABS (anti-lock brake system) module to activate the disc brakes on all four wheels. When the vehicle comes to a standstill, the parking brake module statically applies the parking brake. Once the static load is achieved, the hydraulic pressure is removed. If the parking brake switch is released to the neutral position, or pressed down to the release position, during dynamic apply, braking is cancelled.
The anti-lock brake system (ABS) module monitors the deceleration rate using the wheel speed sensor signals, and adjusts the hydraulic pressure to the disc brakes as required to achieve the required rate. All of the anti-lock control - traction control system brake functions remain enabled in the dynamic apply mode.
The parking brake module incorporates two fallback functions for the dynamic apply mode.
Fallback 1 is invoked if vehicle speed is between 2.5 km/h (1.25 mph) and Vmax when the parking brake switch is selected to apply and the ABS module is unable to fulfill a hydraulic request. When fallback 1 is invoked, the parking brake module decelerates the vehicle, using only the parking brake. The parking brake module monitors the deceleration rate using the wheel speed information from the ABS module, and adjusts the tension of the brake cables to achieve the required rate. During deceleration the parking brake module also uses the wheel speed inputs from the ABS module to operate an anti-lock function for the rear wheels. When vehicle speed decreases to 2.5 km/h (1.25 mph) the parking brake module switches to the static apply mode.
Fallback 2 is invoked if there is a loss of communication between the parking brake module and the ABS module or the CAN bus has failed. When fallback 2 is invoked, the parking brake module decelerates the vehicle using only the parking brake. The parking brake module tightens the brake cables under the control of the driver, no anti-lock function is available.
While dynamic apply is active, including fallback 1 and fallback 2, the parking brake module also outputs high speed CAN bus signals to:
The ABS module, to apply the stoplamps.
The instrument cluster, to sound an intermittent warning buzzer, at 0.5 second on, 1.0 second off.
The instrument cluster, to illuminate the red parking brake warning indicator. The indicator is permanently illuminated except in fallback 2, when it flashes.
DAR Pre-arming
The DAR pre-arming function operates when the transfer box is in high range to reduce the parking brake release time during DAR and to provide a smooth take-off. DAR pre-arming is invoked when:
The ignition is ON.
The transmission is in gear 1, 2 or R.
The vehicle is stationary.
No failsafe tighten actuation has occurred.
Automatic Load Adjustment
While the ignition is on, the parking brake module constantly monitors the input from the force sensor. If the tension of the brake cables goes outside the limits for a given operating mode, the parking brake module automatically restores the tension within limits.
Failsafe Tighten. If, during pre-arming, the vehicle moves, then the maximum cable force is reinstated for the remainder of that ignition cycle.
Automatic Apply. While the parking brake is applied, if the tension of the brake cables decreases by a prescribed amount from the initial setting, the parking brake module automatically restores the tension to the initial setting.
Automatic Release. While the parking brake is released, if the tension of the brake cables increase to a prescribed amount, the parking brake module automatically reduces the tension to zero.
Parking Brake Switch Monitoring
The parking brake module monitors for the following types of fault in the parking brake switch system. If a fault is detected, the parking brake module stores a related fault code:
Short circuits between a pull-down transistor in the parking brake module and battery voltage.
Broken wires and microswitches.
Plausibility.
The parking brake switch has a degree of in-built redundancy. If a single microswitch fault is detected the parking brake module can still determine the operating state of the parking brake switch. Short circuits or multiple failures cause the parking brake module to disable the parking brake switch for the remainder of the ignition cycle. The parking brake module also disables the parking brake switch if a plausibility fault occurs. However, since plausibility faults are usually caused by incomplete operation of the parking brake switch, the parking brake switch is re-enabled if the parking brake module subsequently establishes a plausible operating state.
If a single microswitch fault is detected, the parking brake module signals the instrument cluster to illuminate the amber parking brake warning indicator. On vehicles with the high line instrument cluster, the parking brake module also signals the instrument cluster to display a message advising there is a parking brake fault. During an apply actuation, the parking brake module also signals the instrument cluster to flash the red parking brake warning indicator.
For all other fault types, the parking brake module signals the instrument cluster to illuminate the amber parking brake warning indicator, and, on vehicles with the high line instrument cluster, to display a message advising the parking brake has a fault and is not functioning. If it makes an apply actuation, the parking brake module signals the instrument cluster to flash the red parking brake warning indicator for the remainder of the ignition cycle.
On the next ignition cycle, the warning indicators and the messages are only activated if the fault is still present, although the fault code is retained by the parking brake module until cleared by T4.
Member Since: 05 Feb 2006
Location: ¯\_(ツ)_/¯
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In truth the 30 min became 20 min on later D3 software versions too, in an effort to reduce the time it takes for the vehicle to sleep. The increased force on low range applies equally to the D4 as the D3. It is there to reduce the load on the EPB when not needed yet prevent the vehicle moving with the higher effective torque of the low range.
Thanks for the D4 Topix extract and I note that they mention the change in DAR strategy depending on HIGH/LOW range, so someone at JLR gets it.
Land Rover - Turning Drivers into Mechanics Since 1948
Member Since: 02 Aug 2014
Location: Edinburgh
Posts: 1517
Robbie, DG.
A quick question (that I posted elsewhere with no responce)
How difficult would it be to drive if the EPB was engaged, and what damage would ensue?
2nd Jan 2015 11:37 pm
DiscoStu
Member Since: 09 Apr 2006
Location: London
Posts: 11412
The car won't move with EPB on
2nd Jan 2015 11:39 pm
Robbie
Member Since: 05 Feb 2006
Location: ¯\_(ツ)_/¯
Posts: 17932
... Or if it had drive away release it would release itself. If you applied it whilst moving there would be a short pause then warning bongs, flashing light and the ABS would come fully on.
The only realistic way to drive with the EPB on is with a fault or maladjustment.
Land Rover - Turning Drivers into Mechanics Since 1948
Member Since: 27 May 2011
Location: Sticking the Ex back in the skanks bin
Posts: 2824
If the epb didn't release and you did drive off after applying a decent amount of grunt it would take a mile or two to wreck the rear shoes and discs and possibly the normal rear pads.
Also the heat could possibly kill the rear brakes or severely shorten their life. Then there is gear box wear on the clutch packs and the rear diff and transfer box from the added strain of all this going on.FFRR Owner, very nearly became a D3 owner
Test piloted a new D4 XS SDV6.. Gone and being forgotten i hope!!
D4 HSE 10MY
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3rd Jan 2015 12:07 am
JMack
Member Since: 02 Aug 2014
Location: Edinburgh
Posts: 1517
Thanks guys.
Presumably if it one did drive with it on if mis-adjusted then it would depend on how bad it was as to how noticeable it would be and also this would reflect in any 'damage' caused.
i.e slight mis/maladjustment would be barely noticed and would just result in worn pads with no real drag noticed, but if it was nearly locked on it would be noticed and could damage discs and overheat bearings etc.
3rd Jan 2015 12:09 am
JMack
Member Since: 02 Aug 2014
Location: Edinburgh
Posts: 1517
kp wrote:
If the epb didn't release and you did drive off after applying a decent amount of grunt it would take a mile or two to wreck the rear shoes and discs and possibly the normal rear pads.
Also the heat could possibly kill the rear brakes or severely shorten their life. Then there is gear box wear on the clutch packs and the rear diff and transfer box from the added strain of all this going on.
So you would know about it!
3rd Jan 2015 12:10 am
kp
Member Since: 27 May 2011
Location: Sticking the Ex back in the skanks bin
Posts: 2824
You would indeed but then there are levels less than that as you say but any pad drag over normal results in disc temps getting very hot. Rear calipers are known for this on lots of vehicles FFRR Owner, very nearly became a D3 owner
Test piloted a new D4 XS SDV6.. Gone and being forgotten i hope!!
D4 HSE 10MY
D4 XS 11MY
SSRR Destroyer *2
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If you're parking on a slope, use the kerb to keep your Disco still.
