4WD not working

kennith

Well-known member
Apr 22, 2004
10,891
169
North Carolina
You're going to get spin like that even if everything is working properly. Unless the center is locked, you've got three open differentials. You do have traction control (unless it's failed) which sounds like a cartoon "spring" sound effect behind the dash.

Don't lock that thing on the road, though; not even in snow. Yes, you'll force a little more traction between the front and rear, but you'll still get slip side to side, and now there's no differentiation between the axle housings. That's not good, as the play in the center allows the vehicle to track where you point it without resisting the road conditions.

If you find the slip bothersome, you'll need to look into limited slip or torque biasing differentials.

There is no device in the vehicle capable of causing an actual "problem", in this regard. As Blue noted, you'd need to be missing a driveshaft. That transfer case is all gears. If it was broken, you'd know it; and they're incredibly difficult to break. It's easily the toughest part of the vehicle.

Even if traction control is working, you'll get some of that slip. If all wheels have grip, all wheels are pushing you forward. If one doesn't, and the traction control can't catch it, there's nothing to stop it spinning; but as noted, even traction control will allow it. If it didn't, they'd be nightmares to drive.

Cheers,

Kennith
 
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mgreenspan

Well-known member
Feb 28, 2005
4,605
76
Briggs's Back Yard
Does your vehicle have functional traction control? Has your vehicle been fitted with a center diff lock? Like blue said, do you have a rear drive shaft? What type of tires are you running in the snow and how much snow was there?

My understanding of the way open differentials and an open center differential works is that power will go to all wheels until one loses traction then that wheel spins and the others lose power. This is because of how a differential is designed. If you lock the center diff, the power goes to both front and rear axles evenly and you gain the ability to have one wheel spin in either the front or the rear while the opposite axle still moves forward or backward. With traction control in a DII you get the brakes automatically engaging to trick the diffs into thinking the spinning wheel(s) have traction sending power back to the wheels that lost it when wheel spin first began.

From what you described I cannot tell what is happening because my understanding of how diffs and wheel spin work is that for you to have two front wheels both spinning at the same time you’d have to have installed a front locker, locked your center diff, and removed your rear driveshaft. I doubt you drive around like that so it’s difficult to tell what’s happening.

If your front tires are spinning one at a time, e.g. front left spins, gets traction, front right spins, gets traction then the left begins again, and you’re not physically moving forward while driving in snow, then I’d say it’s time to upgrade your transfer case to one with a CDL or make a ghetto lever if yours has the CDL nipple. Another option is to buy some new tires with better winter traction. It sounds like you’re at the limit of the traction control and need to upgrade something, but I’m assuming what you described is missing details.
 
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kennith

Well-known member
Apr 22, 2004
10,891
169
North Carolina
Does your vehicle have functional traction control? Has your vehicle been fitted with a center diff lock? Like blue said, do you have a rear drive shaft? What type of tires are you running in the snow and how much snow was there?

My understanding of the way open differentials and an open center differential works is that power will go to all wheels until one loses traction then that wheel spins and the others lose power. This is because of how a differential is designed. If you lock the center diff, the power goes to both front and rear axles evenly and you gain the ability to have one wheel spin in either the front or the rear while the opposite axle still moves forward or backward. With traction control in a DII you get the brakes automatically engaging to trick the diffs into thinking the spinning wheel(s) have traction sending power back to the wheels that lost it when wheel spin first began.

From what you described I cannot tell what is happening because my understanding of how diffs and wheel spin work is that for you to have two front wheels both spinning at the same time you’d have to have installed a front locker, locked your center diff, and removed your rear driveshaft. I doubt you drive around like that so it’s difficult to tell what’s happening.

If your front tires are spinning one at a time, e.g. front left spins, gets traction, front right spins, gets traction then the left begins again, and you’re not physically moving forward while driving in snow, then I’d say it’s time to upgrade your transfer case to one with a CDL or make a ghetto lever if yours has the CDL nipple. Another option is to buy some new tires with better winter traction. It sounds like you’re at the limit of the traction control and need to upgrade something, but I’m assuming what you described is missing details.
I'll add just a bit for context, in case someone needs it in the future:

Center differential:

This allows the front and rear driveshafts to rotate at different speeds, obviously; but there's a reason for that. As a vehicle moves through a turn, the rear axle tracks closer to the apex of that turn than the front axle. Some will have noted in life that it's easier to scrape a rear wheel on a curb then the front, and this is why.

What that means is that the rear axle is not actually traveling as far as the front axle. Both rotate at different rates, as a result. This is the only reason you can pilot a vehicle through a turn while maintaining traction. Indeed, the "lack of traction" is where you're traction is coming from.

Were you to lock that center differential, it fixes both driveshafts at the exact same RPM. The front and rear tires cannot rotate at the same rate the road is going past. If it helps, think of tires as paint rollers. They must lay paint down evenly at the same rate they are rolling along the road, and in order to do that, the RPM needs to be variable.

Locked, some or all of the tires are now resisting the motion of the vehicle. Some paint rollers are just dragging paint instead of rolling it down, and anyone who's ever used a paint roller knows that this immediately alters friction. Even if the tires are not chirping, it's happening. When you get to the point at which tire deflection can't absorb it, you'll either get that chirp or... If you're in slushy conditions, control will be severely compromised, and it can happen quickly.

When you see people driving in rallys, on tracks, or in ice with traction aiding differentials of any variety, you're seeing someone that knows darn well they're literally gambling traction in one scenario for another, and they have to drive differently to make it work. They must approach and leave turns differently, as well.

Front and Rear Differentials (third members, etc...):

These do the exact same thing, but from side to side. Again, each wheel on an axle needs to rotate at different speeds. Being open allows them to roll at whatever speed they wish without smearing that imaginary paint. Again, if you limit or remove that differentiation (slip), you're forcing them to do things they don't want to do.

I've got Quaife differentials in my DII. They're not going to be as grabby as a limited slip, nor as capable as a locker; and I like that. By allowing more differentiation than the other two, the vehicle is more stable in sweeping turns and close to the limit than it would be otherwise; but it's still compromising that perfect stability open differentials allow...

...until you exceed the handling limits of the vehicle. At that point you're breaking traction, and at that point these differentials serve a purpose: They take that broken traction and render it less relevant. Each differential technology sits in a different place on that scale. Mine are closest to open differentials. Limited slips are closest to lockers.

Land Rover:

Land Rovers are not four wheel drive vehicles. They are All Wheel Drive vehicles. Yeah, yeah; "Permanent 4X4"... Whatever. Marketing nonsense. All that means is on most you can lock the center. It's still an AWD car. 1% of your customers using a feature 1% of the time doesn't win you a new segment, Land Rover. It just confuses people.

AWD is not a cop-out; it's great for many reasons, but chief among them is having the utility of all four tires as often as possible, without upsetting stability. You're much less likely to become stuck in the first place, and you get the benefits in normal conditions. Think of it as an over-built, over-sized Subaru. All the same benefits, with a fair bit of the same drawbacks. These weren't designed for rock-hopping. They just happen to be quite good at it when appropriately configured.

I know the information here may seem like a given to some, and yes, it's obvious to many people; but it's been obvious for so damned long that nobody bothers to explain it anymore, and without explanation, how are people to know?

If I got anything mixed up in there, let me know. I've got some focus difficulties of late, and I can get things backwards on occasion.

Cheers,

Kennith
 
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Swedjen2

Well-known member
Sep 12, 2018
405
64
California
If you have an early 2002, you might be able to lock it, but it's a crawl underneath and fiddle around process.
The P.O. on my 2002 hooked a wire to the locking lever and had it routed under the passenger seat area.
When he went off-road he reached underneath for the lever and engaged/disengaged it that way. The push/pull method.
Again, he had an early 2002. The later '02s and '03's...you're out of luck.
So your options are: A) Find out if yours can even be engaged or no.
B) Get an actuator lever that works with your t-case - not cheap, but Lucky 8 and others (Ashcroft) carry the lever assembly.
C) Get a 2004 T-case with the proper lever
D) Do nothing and take it
Option D is not and option, IMO.
 
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I'll add just a bit for context, in case someone needs it in the future:

Center differential:

This allows the front and rear driveshafts to rotate at different speeds, obviously; but there's a reason for that. As a vehicle moves through a turn, the rear axle tracks closer to the apex of that turn than the front axle. Some will have noted in life that it's easier to scrape a rear wheel on a curb then the front, and this is why.

What that means is that the rear axle is not actually traveling as far as the front axle. Both rotate at different rates, as a result. This is the only reason you can pilot a vehicle through a turn while maintaining traction. Indeed, the "lack of traction" is where you're traction is coming from.

Were you to lock that center differential, it fixes both driveshafts at the exact same RPM. The front and rear tires cannot rotate at the same rate the road is going past. If it helps, think of tires as paint rollers. They must lay paint down evenly at the same rate they are rolling along the road, and in order to do that, the RPM needs to be variable.

Locked, some or all of the tires are now resisting the motion of the vehicle. Some paint rollers are just dragging paint instead of rolling it down, and anyone who's ever used a paint roller knows that this immediately alters friction. Even if the tires are not chirping, it's happening. When you get to the point at which tire deflection can't absorb it, you'll either get that chirp or... If you're in slushy conditions, control will be severely compromised, and it can happen quickly.

When you see people driving in rallys, on tracks, or in ice with traction aiding differentials of any variety, you're seeing someone that knows darn well they're literally gambling traction in one scenario for another, and they have to drive differently to make it work. They must approach and leave turns differently, as well.

Front and Rear Differentials (third members, etc...):

These do the exact same thing, but from side to side. Again, each wheel on an axle needs to rotate at different speeds. Being open allows them to roll at whatever speed they wish without smearing that imaginary paint. Again, if you limit or remove that differentiation (slip), you're forcing them to do things they don't want to do.

I've got Quaife differentials in my DII. They're not going to be as grabby as a limited slip, nor as capable as a locker; and I like that. By allowing more differentiation than the other two, the vehicle is more stable in sweeping turns and close to the limit than it would be otherwise; but it's still compromising that perfect stability open differentials allow...

...until you exceed the handling limits of the vehicle. At that point you're breaking traction, and at that point these differentials serve a purpose: They take that broken traction and render it less relevant. Each differential technology sits in a different place on that scale. Mine are closest to open differentials. Limited slips are closest to lockers.

Land Rover:

Land Rovers are not four wheel drive vehicles. They are All Wheel Drive vehicles. Yeah, yeah; "Permanent 4X4"... Whatever. Marketing nonsense. All that means is on most you can lock the center. It's still an AWD car. 1% of your customers using a feature 1% of the time doesn't win you a new segment, Land Rover. It just confuses people.

AWD is not a cop-out; it's great for many reasons, but chief among them is having the utility of all four tires as often as possible, without upsetting stability. You're much less likely to become stuck in the first place, and you get the benefits in normal conditions. Think of it as an over-built, over-sized Subaru. All the same benefits, with a fair bit of the same drawbacks. These weren't designed for rock-hopping. They just happen to be quite good at it when appropriately configured.

I know the information here may seem like a given to some, and yes, it's obvious to many people; but it's been obvious for so damned long that nobody bothers to explain it anymore, and without explanation, how are people to know?

If I got anything mixed up in there, let me know. I've got some focus difficulties of late, and I can get things backwards on occasion.

Cheers,

Kennith
Kenneth, I really appreciate your write up. The traction control light came on and has stayed on. What should I look to next?
 

SCSL

Well-known member
Apr 27, 2005
4,112
131
Search for "3 amigos" in the forum. This is an ABS typical trouble. It is an additional issue more related with brakes. 4WD should still working.

Regards
He’s got no 4WD in that 2002 car. Since he’s got the three amigos, his ETC isn’t working. So he’s rolling AWD with no TC, hence the traction problems.
 

kennith

Well-known member
Apr 22, 2004
10,891
169
North Carolina
Kenneth, I really appreciate your write up. The traction control light came on and has stayed on. What should I look to next?
You'll want to investigate the specific codes.

Typically, it'll be a shuttle valve fault that's actually related to the shuttle valves, a poor internal connection that can be bypassed, malfunctioning wheel speed sensors, or even the little rings in the hubs with which they interact.

This is one subject in which searching will actually yield quite a few good results. Normally it's a pain in the ass to search for stuff, but sowing this particular seed into the search bar will feed a family for months.

The actual solutions are pretty solid. When this first started cropping up years ago, people didn't really know what the issues were. Looking at it all over time, Land Rover probably could have fixed it, but I don't think they had it figured out, either.

Cheers,

Kennith