When does TC not work

[simonl8353]

Had a minor problem getting stuck in a hole in a residential country lane the other day :eek:. Very embarrassing.

What is confusing me is that normally the Traction Control kicks in when required but this time it didnt. Can anyone explain why?

Heres my situation, I have a standard D2 with all the usual ES bling (ACE, SLS etc) and wanted to take a look at the articulation, so on seeing an innocent looking 6 ft at it widest point, 3ft deep drainage gully/pot hole thing on a gently inclined bank, positioned then slowley reversed the D2 right rear in to it, then WOMP!, the gully was about 1ft deeper when the soft vegetation gave way and I ended up with the rear drivers side deep in the hole, rear diff resting on the ground (lip of ditch) and the front near side way up and only just touching the ground. The whole car was at about 25deg down on the drivers side and 10 deg up at the front, sitting heavy on the back. The sides of the ditch wer about 45deg.

Into low ratio but could not get the vehicle to budge forward or backward.

after only a couple of minutes, a passing mountaing biker came by, "you have no rear drive" he said "you need to lock the diff". You see the only wheel turning was the front n/s that was virtually in fresh air (oh for the CDL to be reinstated I thought). I explained the delights of the TC system to him, asked him to give it some gas while I checked, sure enough, only 1 wheel trying tio drive and no eveidenc of TC assisting. :blink:

I was able to bounce on the n/s front to give some traction and finally got the D2 out backwards.

Thanks to this bloke for stopping to assist otherwise I'd have been there quite a while. I wasnt carrying any recovery gear as I was literally on my way home from the park with my son and dog in the back.

So does anyone know what was confusing the TC to prevent it from braking the front wheel sufficiently to put drive to another wheel, any suggestions?

[Blknight.aus]

If youve stopped and shut down the restarted and dont go over about 7KPH then the TC wont activate as it wont have a base line to work from.

If youve blown a fuse that controls the TC or ABS the same deal applies.

so far thats the only reasons I know of that it wont try to do its job. If its a second hand vehicle the posability exists that someone has fitted a disable switch and hasnt told you about it. (dont ask me why they do, they just do)

it wont help you but it will work if your so badly hung up that the pull required to get you moving exceeds the traction you have availalble.


IF you dont get the ABS/TC/HDC lights turn on when you first turn on the ignition then you have electrical hassles.

[100I]

Yours would have the CDL that you can activate with a spanner - 10mm I seem to recall. Put a $2 supermarket one in your glovebox or under the seat.

[long stroke]

Lucky it wasn't a toyota driver that came along:D

TIM.

[Blknight.aus]

hed probabley just get out and whinge about his seats if he did.

[simonl8353]

Thanks Dave, Dan,

I cannot recall switching the ignition off, maybe I did for a while. The ABS TC HDC are still functioning, no amigos. Very good advice to know that in the future. cheers

I pack a 10mm spanner all the time, a very necessary addition as this also is the only essential tool to change the SLS airbags in an emergency. Getting to the spigot would have been near on impossible though, but yes, that was plan C.

Yes my biggest worry was a Toyota, but as it turned out the guy that stopped owned two 4WD's (dont know what) so my apologies to every LR owner for ruining our reputation.

[4X4V8]

The TC is pretty crude in the D2 compared with later cars, and you also need to aviod giving them too much throttle when traction is very limited as it sounds in your case. Clearly the stupid BMW engineer who signed off on taking out the diff lock lever should be shot, cos I bet you would have had a better chance with at least a back wheel helping out.

Did you try the extended mode for the rear suspension? I wonder if it makes any difference when articulated like that? May have increased the weight on the front.

[simonl8353]

The TC is pretty crude in the D2 compared with later cars, and you also need to aviod giving them too much throttle when traction is very limited as it sounds in your case. Clearly the stupid BMW engineer who signed off on taking out the diff lock lever should be shot, cos I bet you would have had a better chance with at least a back wheel helping out.

Did you try the extended mode for the rear suspension? I wonder if it makes any difference when articulated like that? May have increased the weight on the front.
Thanks 4X4V8, I tried all throttle speeds from a crawl to ..all of it!
I went in to the ditch with the SLS pumped up in Offroad Mode, so there was no more height that Extended Mode could have added.
My initial thinking is that there may be a maximum braking force that the TC brain will apply to the spinning wheel and not beyond, maybe to avoid unnecessary stress on the axels of the other wheels. But I'm just guessing here.

Now and then I engage the HDC to shake up the shuttle valve (on a small bitumen hill near my home), I think I'll check it again tonight and make positively sure its all still working, assuming if the HDC works the TC should be working.

[Blknight.aus]

It also uses the same system as ABS so a good hard braking application on a gravel road is all thats needed (read your books and your actually supposed to do this about once a month to keep the valves moving same same as turning the aircon on even though its about -400000 degress outside ATM)