4x4 not working in high. HELP!!

[JNE13]

I have a 2003 Disco. Im located in NY and few weeks ago we got some snow. I has zero traction and kept getting stuck. I realized only one wheel was getting power and my truck was a one legger. I thought my transfer case was bad. Then I put the truck in low and then my 4x4 worked perfectly but obviously i can't drive around in low. Any ideas of why it works perfectly in low but not in high?

[BogMonster]

It sounds like the electronic traction control isn't working in high range. Without it the D2 is useless as all the diffs are open, so as you have found you can get stuck with just one wheel spinning. You can find that very low speed wheel spin will not trigger the ETC but if you give it a bit of throttle then it should do, if there is nothing there I think you need to get it plugged into a computer to test the system properly. Usually if there is a problem there are warning lights etc to give it away.

[Chicken Drumstick]

D2's are always 4wd, however the centre diff is an open diff (as are the axle diffs). This means it will essentially become 1wd drive on slippery surfaces.

D2's are fitted with electronic traction control. This brakes a spinning wheel, which in turn will cause the opposite wheel to rotate providing traction. With an open centre diff, the TCS can work overtime however.

TCS also needs some wheel speed to work and you need to keep on the gas pedal a little bit (don't rev the nuts off it, more a constant power, but don't back off).

Most D2's still have a lockable centre diff all you need is the lever kit to allow you to lock it. This will make a huge difference in these conditions (this kit will make the D2's driveline work like a Defender or D1's does). However you need to check, as some years of D2 you can't fit the kit too.

As for the actual problem, it could be the TCS isn't working in high range, although that seems odd as I don't think the TCS knows what transfer range you are using. Of course it might be the TCS just didn't work as well in high range due increased speed the wheels are driven at. Or maybe the TCS wasn't working at all in either range and just the lower wheel speed of low range was making it appear to drive better. Do you have any warning lights on? Could you feel/hear the TCS? It should make a sort of clicking/pulsing sound and you might feel it on the brake pedal.

Remember in snowy conditions, good tyres for the conditions will transform a vehicle - any vehicle. If you aren't running some winter snow tyres, you might want to consider them.

This is the kit I mentioned:

http://www.roversnorth.com/ProductDesc.aspx?code=RNA199&type=0&eq=&key=it

Although seems very pricey. I suspect if you hit ebay (specifically ebay.co.uk) you could pick up these parts used and shipped to you for only a fraction of the cost.

[Bowie69]

...and an awful lot cheaper from Ashcroft, I expect even when you factor in transatlantic carriage:

http://www.ashcroft-transmissions.co.uk/miscellaneous/disco-ii-difflock.html

[JNE13]

I do have lights on, the "3 amigo" lights. TC, ABS, Hill. I originally thought this may be the issue but when i took it to a LR mechanic he said one issue has nothing to do with the other. Then again he was a little shady and told me an ABS shuttle valve to fix the light issue was $900 and i ordered it brand new for $80. Anyways that part should be here any day now to clear those three lights hopefully. May that be the cause of my traction/4x4 issue. Today i took it to another shop to get another opinion. And of course for that second guy the 4x4 was working fine which he explained to me its really a 3wd car bc the drivers front gets limited power not full like the other 3, is that correct info? Also 3 amigo lights weren't on yet since i turned off the car and it reset when the 4x4 was working.

[Escape]

As said, the Discovery 2 is a permanent 4x4, with 3 open differentials, so each wheel gets the same 25% of power. If one wheel loses traction, no power will be transmitted to the 3 other wheels, and you're stuck. Traction control will help as it uses the brakes to slow the spinning wheel. Most problems with the 3 amigos (ABS/ETC) are caused by the sensors, not the valve block. You would really benefit from a mechanic who knows Land Rovers...

Filip

[Chicken Drumstick]

I do have lights on, the "3 amigo" lights. TC, ABS, Hill. I originally thought this may be the issue but when i took it to a LR mechanic he said one issue has nothing to do with the other. Then again he was a little shady and told me an ABS shuttle valve to fix the light issue was $900 and i ordered it brand new for $80. Anyways that part should be here any day now to clear those three lights hopefully. May that be the cause of my traction/4x4 issue. Today i took it to another shop to get another opinion. And of course for that second guy the 4x4 was working fine which he explained to me its really a 3wd car bc the drivers front gets limited power not full like the other 3, is that correct info? Also 3 amigo lights weren't on yet since i turned off the car and it reset when the 4x4 was working.

Not sure I can offer much more help. However it may well help you if you read up on how 4wd systems work in general and then specifically the D2. It'll help you understand the problem and what any mechanic is likely to tell you.

I have no idea what is meant by 3wd and it sounds like total rubbish.

The D2 is permanent 4wd, it does not have a 2wd option.

The drivetrain consists of 3 differentials (reading up what a diff is and how they work will help you here).

There is a centre diff which splits power front/rear 50:50 this is an open differential.

On each axle there is also an open diff, which again splits 50:50, thus each wheel gets 25% drive.

When one side of an open diff spins, it will not provide drive to the other side. Hence why on rwd cars with an open diff they will only spin 1 wheel. If you want to do do burn outs you need a Limited Slip Diff to make both wheels spin.

The D2 is no different in principle, only it has 3 diffs to think about.

If say the front left wheel is on ice and spins, then the front right wheel won't rotate because the left one is not seeing any loading. But because the centre diff is also open, this means most/all of the power of the engine will be going to the spinning front left wheel and not to the rear either.

In older Land Rover's they have a locking centre diff. With this locked it makes the 4wd system act just like any other 4wd system from Ford, GM, Jeep, etc. In the above scenario with a locked centre diff, power would still be sent to the rear wheels, only the front right wouldn't be seeing power.

The D2 doesn't lock the centre diff, it uses traction control instead. When it senses any wheel spinning it will brake that wheel, this applies loading on it, which will make the wheel opposite also rotate. This in effects is an electronic simulation of a diff locker.

So in the above scenario, if the front left spins, it would brake that wheel, this would have two affects. One to make the right front rotate, and two, to make the rear wheels rotate. The end results is very similar to having a locked centre diff (arguably better in some cases).

The down side is relying on TCS to keep all 4 wheels spinning means the system has to work hard. Many people retro fit the locking mechanism to D2 for the centre diff, this way the TCS only has to deal with one diff per axle and works even better.

My hunch would be if there is any problem with the TCS/ABS then this would affect or stop this working. In low range it was just likely that the torque multiplication of the gearing made the vehicle perform better.

[Nigelw]

Not sure where you are, but your mechanic experiences are not unusual, ie, $900 to replace an $80 part

I would suggest you seek out a local club and see who is using who for garage repairs for complex stuff you can't handle yourself.

As for the 4X4, LR made a fundamental flaw with the D2 in believing the TC alone was strong enough and removed the center diff lock (CDL) the problem there is that you don't have the true 50/50 split between front and rear when you need it, and as you have found, your truck with disabled TC and no CDL can become one wheel drive, although I anot sure why the TC is working in low range and not in high?

Good luck with sorting this out.