Thread: Hill Descent Control

The sports mode in low range puts the gearbox into manual, so you can keep it in one gear if you are doing a difficult climb etc

Originally Posted by AussieAub

Why use the Sport Mode button?
Never heard or done that one before.....(curious)

Force of habit I guess ... makes the auto act like a clutchless manual ... sport mode ON, 2nd low, and it stays in that gear regardless ... then you can switch the HDC on/off during a decent, but the box ALWAYS stays in the gear selected, so as long as the overun gets the engine revs up to 2000rpm the TC locks and you have the benefit of engine braking & HDC ... makes the HDC less agressive .... if you leave it in Drive, there's next to no engine braking, and when you turn the HDC off the vehicle can run away down hill ... sport mode or not.

Originally Posted by Fluids

Force of habit I guess ... makes the auto act like a clutchless manual ... sport mode ON, 2nd low, and it stays in that gear regardless ... then you can switch the HDC on/off during a decent, but the box ALWAYS stays in the gear selected, so as long as the overun gets the engine revs up to 2000rpm the TC locks and you have the benefit of engine braking & HDC ... makes the HDC less agressive .... if you leave it in Drive, there's next to no engine braking, and when you turn the HDC off the vehicle can run away down hill ... sport mode or not.

It's Manual Mode when you are in Low Range. Sport Mode is strictly high range.

I don't see there is much benefit from engaging Manual mode on descents. The main difference from normal/economy mode is that manual will prevent downshifting unless there is a risk of stalling the motor. When you are descending the tendency is for the auto to upshift. If you have selected 1 or 2 the auto won't upshift to a higher gear, and won't attempt to (or can't in the case of 1) downshift while descending, so you end up with the same result regardless of mode setting.

In low range the TC will only lock up when the revs are above 1800 rpm with 0% throttle and unlocks pretty quickly once the revs drop below that point. In Low 1 with stock tyres 1800rpm equates to a road speed of about 8.6 km/h, and is 1.6km/h above the HDC minimum target speed for 1. It appears that the TC lock up is designed to give additional engine braking when decelerating after throttle application, or when engine braking with unlocked TC is allowing road speed to creep above the HDC target speed.

I do agree that using low 1 or 2 is the best way to drive with HDC. This is also what LR recommend in the D2 owners manual. Engine braking takes care of speed control for the most part, and HDC is left to monitor for and respond to wheel slip.

cheers
Paul

Originally Posted by OffTrack

It's Manual Mode when you are in Low Range. Sport Mode is strictly high range.

If you have selected 1 or 2 the auto won't upshift to a higher gear, and won't attempt to (or can't in the case of 1) downshift while descending, so you end up with the same result regardless of mode setting.

That's what I thought. I have an auto box, and still can't see any advantage to being in "sport" mode to use HDC. Or is it different with a manual box?

I do agree that using low 1 or 2 is the best way to drive with HDC. This is also what LR recommend in the D2 owners manual. Engine braking takes care of speed control for the most part, and HDC is left to monitor for and respond to wheel slip.

Definately!

Originally Posted by AussieAub

Why use the Sport Mode button?
Never heard or done that one before.....(curious)

In low range, the Sports button is actually a Manual button, in that the auto sticks in the gear selected, and doesn't change.

First time I heard the noise, I almost soiled myself. I was sure I'd buggered up something expensive.

Originally Posted by Pinelli

In low range, the Sports button is actually a Manual button, in that the auto sticks in the gear selected, and doesn't change.

Sorry mate, still not getting this....
I thought in high OR low range auto, that if I put the box into 1, then it wouldn't go up to 2, if I was in 2 it wouldn't go up to 3, but could go down to 1, and in 3 couldn't go up to D but could go to 2 or 1 as necessary?

Surely thats how it works ALL the time, high OR low range?
From what I'm reading on the posts (maybe not understanding correctly), is that, say, if I'm in 2 with HDC on and hit the "sport" button, it will stay in 2 irrespectively, EVEN if it needs to go to 1?
Surely THAT can't be good...?!?!

I see nothing on page 103 of my handbook - Gearbox & Transmission - Sport Mode - to tell me anyhting different (sorry, no access to RAVE from this PC to copy & paste, and can't be bothered to type it all in!)

Bit confused.....

1. my 2c on target speeds come from the Rave CD and were posted a while ago, see here
http://www.aulro.com/afvb/805934-post23.html

As for actual operation, long ago I used it but always found it a tad too fast and too slow to engage. I see the the D3 and D4 has a much more reactive HDC and is much better.

Nowadays and with very little practice you get more downhill control in a D2 if you to apply left foot braking and drive through the brakes.

2. Also when in low range the "Manual" mode can be selected to make the gearbox behave just like a manual box, where the driver must move the selector to change gear (D=4th) giving you a bit of engine braking thus some extra control for the driver. However, it will still automatically downshift to prevent a stall. ...Keiren, have no fear, your 2nd sentence is still correct. I thought in high OR low range auto, that if I put the box into 1, then it wouldn't go up to 2, if I was in 2 it wouldn't go up to 3, but could go down to 1, and in 3 couldn't go up to D but could go to 2 or 1 as necessary?

Originally Posted by AussieAub

Surely thats how it works ALL the time, high OR low range?
From what I'm reading on the posts (maybe not understanding correctly), is that, say, if I'm in 2 with HDC on and hit the "sport" button, it will stay in 2 irrespectively, EVEN if it needs to go to 1?
Surely THAT can't be good...?!?!

This section taken from page 44-17 of RAVE gives a pretty concise summary of the three Auto operating modes:

Economy, sport and manual modes
During the power-up procedure after the ignition is switched on, the EAT ECU defaults to an economy mode. Pressing the mode switch causes the EAT ECU to change between the economy mode and the sport or the manual mode, depending on the range selected on the transfer box:

• If the transfer box is in high range, the EAT ECU changes to the sport mode and illuminates the sport mode warning lamp in the instrument pack. In the sport mode the gearbox is more responsive to accelerator pedal movement. Downshifts occur earlier and upshifts occur later.
• If the transfer box is in low range, the EAT ECU changes to the manual mode and illuminates the manual mode warning lamp in the instrument pack. Kickdown is disabled and the EAT ECU maintains the gearbox in the gear selected on the selector lever (D = 4th gear) to give improved off road performance. Downshifts occur only to prevent the engine stalling. From a standing start, the vehicle pulls away in 1st gear and, if a higher gear is selected, upshifts almost immediately to the selected gear (shifts of more than one gear can occur).

After a second press of the mode switch the EAT ECU reverts to the economy mode, for the range selected on the transfer box, and extinguishes the related mode warning lamp in the instrument pack.