Tracker1

What is the proper way to use all the transmission features? In what circumstances?

The vehicle is always in 4 wheel drive. OR is the considered an all wheel drive vehicle until differenntaial is locked?

The four wheel drive stick is in high for most purposes. And the normal transmission stick is on drive.

The transmission is usually in drive, but low 2,3,4 are available. How's this differ from moving 4wd stick to low?

When 4wd selector is in low, what selection is made on regular transmission stick? Drive, 2,3, 4? Does it matter?

Then there's the second gear start button. This can be used in 4wd high/ reg transmission high? But why not just put ref transmission stick in second gear?

And when to use diff lock in high 4wd/ drive reg rensmission?

Then there the downhill button. What should I be in for this? (Tested once got an horrible thumping noise...

chiph9

First rule is never ever lock the center differential when on a high-traction surface like pavement. If you're on a low-traction surface (ice, snow, dirt, sand) you can lock the center differential at any speed.

The next thing to realize is that the transfer case, with it's high and low range gearing, is after the transmission. So if you're in high range, you get the normal 1-5 gearing. If you're in low range, you also have the normal 1-5 gearing but the transfer case will reduce the number of revolutions to a lower number, so you won't go as fast. But because of how low range works, you'll have more torque to climb over obstacles (you won't need to rev the engine as much). Try this yourself with a parking curb.

When driving on snow and ice, do not use low range unless you're trying to get someone (or yourself) out of a ditch. The extra torque will mean you'll just lose traction at the tires that much easier. Buy snow tires if you live in Michigan/Wisconsin. The GX has a switch under the steering wheel that lets you choose between two sets of tire pressure sensors, so if you have the money, buy two sets of wheels - one for summer and one for winter, and just push the switch in when the winter set is mounted (tell the tire company about this so they program it right).

The second gear start button will prevent the transmission from starting in 1st gear. This reduces the amount of torque so you'll have less chance of losing traction in snow. So if you live in Michigan/Wisconsin and you have fresh snow, use snow tires, stay in high range, consider locking the center diff, and use second start. Once the roads are plowed unlock the diff, and you can stop using second-start.

The downhill button is only useful offroad. Be in low range and in 1st gear (manually select it). It will use the ABS pump (the noise you heard) to control the brakes and keep your speed down, so you can concentrate on your steering & wheel placement.

Because the vehicle is full-time 4WD (not all-wheel-drive) if you ever get towed, make sure they use a flat-bed tow truck. It is technically possible to tow for very short distances with just one set of wheels on the tow truck IF you put the transfer case in neutral. I have never met a tow truck operator that knew enough to do that, so demand a flat-bed.

Chip H.

ALAN553

there were instructions on a placard on the drivers sun visor, also, if i remeber correctly proper usage and precautions are in the manual. If you are missing the manual, you can register at MYLEXUS, enter your vin and see the manual in PDF format.


the 2.3.4 on the shifter is the same as any car.....controlling the shift on an automatic, vs clutch and stick. you will never need to use L on transfer case...that is mainly for off roading....pushing the 4X4 button locks the front diff so both tires spin at the same speed...not to be used on dry road while turning.

chiph9

More on gear ratios -

1st: 3.52
2nd: 2.04
3rd: 1.40
4th: 1.00
5th: 0.72

Transfer case High: 1.00
Transfer case Low: 2.57

Final drive (the front & rear differential gearing) : 3.73

To get the effective ratio, you multiply the transmission ratio (for the gear you're in) by the transfer case ratio (for the range you're in) by the final drive ratio

So 2nd gear high range is: 2.04 x 1.00 x 3.73 = 7.61
2nd gear low range is 2.04 x 2.57 x 3.73 = 19.55

If you include the engine rpms in the equation, this tells you how fast the drive axles are turning relative to the engine speed. But you divide rather than multiply since the gearing reduces the rpms.

2nd gear high range: 3000 engine rpm / 7.61 = 394.21 rpm at the axle (wheel hub)
2nd gear low range: 3000 engine rpm / 19.55 = 153.45 rpm at the axle

This shows you that your speed will be reduced by more than half when in low range. Because rpms and torque have an inverse relationship, this also means that you'll have more than double the torque when in low range.

Notice that fifth gear ratio is below 1.00 - this is because it's an overdrive gear for highway economy. Higher rpm at the wheel hub means you're going faster. But less torque.

5th gear high range: 3000 engine rpm / (0.72 x 1.00 x 3.73) = 1115.24 rpm at the axle (and you'd be going somewhere around 100 mph)

Chip H.

chiph9

One more thing about using neutral on the transfer case -- you should be aware that it disconnects the engine and transmission from the axles.

This means that the "P" position on the transmission has no effect - the vehicle can roll away.

There is a red light on the dash to warn you about this. But you should develop a habit of using the handbrake when parked on a slope, even if you leave the transfer case in high. If for no other reason that it makes shifting out of P into R or D easier (because it relieves pressure on the gearing in the transmission).

Chip H.

tz693

Very informative

Tdoll

I am confused by this post. In this post you state that the 4x4 button is to lock the front diff. I thought the 4x4 button was to lock the center diff. Can someone clear this up?
Thank you!
Todd

ALAN553

i beleive it locks that too and you loose the computerized vehichle dynamics, ie where to transfer power under wheel slippage, instead of full time all wheel drive...which directs power to the front wheels when needed, vs 4x4 which locks it. both wheels spin at the same speed, hence the skipping sound when trying to make a turn on dry pavement. thats my understanding of the whole thing...fact is.....i have never used the L except sometimes to get the truck up on 4 ramps....i occasionally use 4x4 on unplowed deep snowy roads...not too many of them anymore here in the northeast...brining the roads prior to storms makes short work for the plows...down to black top on the first run...and i have never needed to use 2nd start...the truck just goes...oh one other thing...i do have dedicated winter tires but most tire shops can program TPM's to the same code for all 8 wheels so you no longer need the switch for a second set.

chiph9

There are no locks on the front or rear diff from the factory. You can buy aftermarket lockers for them - cost is around $2500 for the ARB products from what I've seen.

Chip H.

IanB2

Excellent info in your post, but I disagree that the GX is full time 4WD (not all wheel drive), 4WD is just Toyota marketing speak for AWD.

4WD = AWD, 4WD does not = 4x4. With the CDL locked, the front and rear axles get 50/50 power sent to them, this = 4x4. With the CDL unlocked the center diff works its magic to send power to the front and rear axles as traction dictates, with the CDL unlocked the truck is in AWD. These trucks are full time AWD.

These trucks also benefit from ATRAC, which acts as an electronic LSD for the front and rear differentials, not as good as lockers, but a whole lot better than open differentials. ATRAC uses the ABS to apply brakes to a spinning tire, so the power is routed to the opposite tire on that axle which may have better grip. Without ATRAC a spinning tire would continue to spin, and that axle would lose the ability to put power to the ground.

Tdoll

I feel like 4WD and 4x4 are the same, so it's just semantics. We have the ability to shift our transfer case to Low or High, this to me signifies it's a 4x4. I look at AWD as street vehicles or non off road vehicles ( WRX is an exception ). They run around in 2wd unless the computer senses wheel spin, at that time the computer will send power to 1 wheel and then the other to search for traction.
Our GX's roll around with power front and rear all the time, so for me that 's full time 4x4 or 4 wheel drive ( 4WD ), with the ability to run in "Part Time" 4wd ( locked CD ). I agree though, good info!

IanB2

That's the thing though, our GX's don't roll around with power front and rear all the time UNLESS the CDL is locked. Things get tricky in that the center diff is an excellent one and shifts power around very well, compounded by having ATRAC on the front and rear differentials, but until the CDL is locked sending power 50/50 to both axles, these trucks are very much AWD.

A transfer case with high and low range changes the gearing ONLY, not where the power is routed. I can't remember if shifting to low range automatically engages the CDL or not, but its the locking of the CDL that provides power to both axles, not the change in gearing. It's the ability to lock the CDL that signifies 4x4, not the selectable transfer case.

Part time refers to the ability to run in 2wd OR 4x4, which of course a GX470 can't do as it's "Full Time 4WD" = AWD.

Fun fact: all manual transmission Subaru's have 50/50 front/rear power distribution, not just WRX's, and auto trans WRX's are not 50/50 biased.

Tdoll

I am fairly sure my GX rolls around front and rear wheels driving. I can feel the binding like every other 4wd or 4x4 that's Shfted into or full time 4wd. Example: my 2000 Jeep XJ had the ability to drive around in 2wd or 4wd full time. That is to say you can drive it on dry pavement and not mess up anything. However, if you shift into 4wd Part Time, you need to be on loose surface. I put mechanical lockers in front and rear. After that there was no driving in 4wd anything on dry pavement.
My GF's Grand Cherokee Laredo also was full time 4wd and I know for sure it rolled around with front and rear driving. I had a 98 ZJ, it was full time 4wd and it drove front and rear tires all the time. None of those vehicles had a CLD. I am not sure of the transfer cases on the grand cherokee's that I mentioned, but the XJ has a NP241.

after rereading your last post I might be misunderstanding what you said. I do not believe the GX rolls around at 50/50 without the CDL. But does that mean that unless the power is 50/50 it's not a "true" 4x4 to you?

Tdoll

After a little research, I am going to say that the GX does in fact drive around ALL the time in 4wd. That is to say the front and rear wheels are driving the vehicle all the time. That is possible due to the Center Differential. The CD is just like a open diff. It allows the front and rear drive shaft turn and different speeds. When locked that Center diff sends equal power to both drive shafts turning them at the same speed. Just like a locker in the front or rear diffs does to their axles. The Transmission in our GX has a Center Differential "Gear" that acts like spider gears and connects the transmissions output shaft to the front and rear drive shafts of the transfer case. This means the GX is Full Time 4WD. ATRAC uses Sensors at each wheel to detect wheel spin, once detected ATRAC will hit the brakes on the wheel slowing it down and reverting power back to the wheel with traction. It kinda tricks the diff.

IanB2

"after rereading your last post I might be misunderstanding what you said. I do not believe the GX rolls around at 50/50 without the CDL. But does that mean that unless the power is 50/50 it's not a "true" 4x4 to you?" Short answer, yes. We need to get the terminology straightened out so we're all talking about the same thing. 4wd is Toyota marketing speak for AWD.

Equal power sent to the front & rear axles = 4x4. On the GX470, this only happens when the CDL is locked.

The GX470 has open diffs in front, rear, and center, only the center is lockable (to achieve 4x4 mode), but the F&R have ATRAC which functions as an electronic LSD.

"When locked that Center diff sends equal power to both drive shafts." This is true, and we agree on this. It then stands to reason, when the center diff is NOT locked, it does not send equal power to the front & rear axles, right? If it is not sending equal power to the front and rear axles...it's not in 4x4...it's in AWD.

The center diff used in the GX470 is the same Eaton unit used in Audi's Quattro system, which I think we can all agree is an AWD system. The GX470 has the ability to lock the CDL which the Audi does not, which provides us with 4x4.

To be clear, I'm not saying the GX470 is not a 4x4, I'm saying it's not "Full Time 4x4". AWD vs 4x4 isn't a car vs. truck thing, it's about how power is routed to the wheels.

I also own a '93 Toyota Land Cruiser 80 series, says "Four Wheel Drive" right on the side, mine has locking center, front, and rear diffs. Under normal driving, it's AWD as well. Lock the CDL, 4x4. To prove this is the case, here's an experiment I'm able to do:
-I have manual hubs on the front wheels, allowing you to disconnect the front wheels from the drivetrain, from factory there were drive flanges in place which mean the hubs were always connected to the drivetrain
-If I have all diffs unlocked, and the front hubs locked, the truck drives as normal, AWD
-Same conditions as above, but I unlock one of the front hubs, truck won't move, all power is routed to the front axle, to the side with no resistance (the spinning tire), still AWD
-Same conditions as above, but I lock the CDL, truck move again, as power is now being routed to both F&R axles, 4x4

Later year 80 series Land Cruiser's got a viscous coupler in the center diff, which acts as a LSD in the center diff, which would muddy the results of my experiment, but wouldn't change the fact the truck is full time AWD. The center diff in the GX470 is an excellent unit, and does a great job of putting power where it can best be used, but when unlocked, the truck is not in 4x4 mode, it's in AWD mode.

The awful fuel economy is attributed to the large body, heavy weight, and thirsty V8 engine. Compare to a same year Tundra with part time 4x4 for proof of same.