Thread: Discovery 4 Restricted Gearbox Mode

If you're travelling slowly in high range then the gbox oil could be overheating from torque converter slippage, in which case use low range.

I'm not sure what you mean by having the car in 4WD since it is always in 4WD. However, I agree with Graeme about the overheating transmission if you are not using low range. The D4's systems all adapt to off road driving when it is in low range so the car is designed to be used in low range in slow off road conditions.


I once used high range on a beach in Esperance to try to keep up with my son in law who was flogging along at about 80 in his 80 series. After a while the car just started losing power until we got really slow and had to stop and then got bogged! I think the transmission was over heating so it cut engine power to reduce the heat. Put it in low range rock crawl, got out of the bog and then drove the rest of the way at a proper speed (below 60) in low range sand mode, with no further problems.


I always use low range off road and have never had a problem, except that one time when I used high range and pushed the car too hard in difficult conditions.


Bob

LR experience "driver" told me not to bother selecting special programme in the hill work in the D4 at the weekend. Apparently the D4 works it all out for itself (car leaning downhill will make it engage cdl ! ) I did use Hdc and it worked a treat! Maybe grass gravel setting is making the tranny work too hard in the conditions because it's trying to avoid wheelspin. Did the dealer report any faults from the bcu or the tcu ?

Originally Posted by Meken

LR experience "driver" told me not to bother selecting special programme in the hill work in the D4 at the weekend. Apparently the D4 works it all out for itself (car leaning downhill will make it engage cdl ! ) I did use Hdc and it worked a treat! Maybe grass gravel setting is making the tranny work too hard in the conditions because it's trying to avoid wheelspin. Did the dealer report any faults from the bcu or the tcu ?

The best way to get an understanding of what the various off road modes do, other than purchasing Gordon's (GOE) invaluable book, is to look at the FAQ. I don't think that the "driver" gave you a very good understanding of what is actually happening, from your comments.


Bob

Thanks Bob, he did explain quite well the modes (and I did know the principles but not exactly what the car is doing mechanically - locking diffs etc).
I think more the point he was making was the rocky loose-ish tracks we were climbing/ descending did not require any special tr mode selected (would have only been mud/ruts or rock crawl anyway) and the car was doing it on the fly anyway as we had the display on and could see the cdl or the rear diff locking unlocking as we drove along. - just my 2 bobs worth

The latest RRS has the auto setting for the TR so it sorts it out itself.
The D4 doesn't,i would use the mode that is needed.

Sure I don't disagree - especially sand, but we did do all of the circuit in normal mode in low range and it wasn't going to be stopped

The D4 will work OK in standard setting but it will work so much easier and better in the correct setting for the terrain, especially in low range. It is still a 4WD with traction control and locking centre diff to suit the traction demands, even in the standard terrain setting or on road.


The main thing is to get out there and try it all out and enjoy the capabilities of the machine.


Bob