4wheel drive system

[svndedlysyns]

Hello all!! I am new to this forum as i just bought a 2004 4runner V6 sr5 4x4 a couple weeks ago and i have never owned a 4x4 before this so i am excited. I have what the owners manual calls "Four- wheel drive system(multi- mode four- wheel drive model)".

My first questions: it says you can drive in H4 with a unlocked differential on regular roads. Is this safe to do? Would this be considered full time 4x4 while in H4? As i read this article SUV buyers guide he is saying in a 4runner you cant use 4 wheel drive on regular roads. Its hard for me to take anything this guy in the article serious as he sounds like a dick. The owners manual also says different then the guy in the article. Is this guy just ignorant? Or is what he is saying true?

Second question: in the owners manual it states you should drive in 4 hi in a unlocked differential for atleast 10 miles a month to keep the front drive components lubricated. And how many people actually do this. Should i take this bit of information seriously?


Third question: Does it seem like the unlocked and locked differentials signs should be opposite. When i see the x on the sign it seems to me that says unlocked. While the straight line would be locked in my mind.

Well any help with this would be great and i am excited to join this forum. And find out everything about the 4runner i can.

 

[BCfish]

1st question: You can drive in 4H in all road surfaces even dry with it unlocked numerous people on here run 4H all the time from fall until spring. In fact you can technically use 4Low unlocked on all surfaces. That guy don't know dick all about a 4th Gen.

2nd question: That's a good rule of thumb as well as to put it on 4Low once a month or so to keep the actuator working as number of people here have had a problem with them but not using it.

3rd question: Never really thought of this.

 

[having fun]

#3- When in 4wd,the green light will be on, in 4lo will say 4lo with it.
When the yellow 4 tire symbol comes on below the green one, YOU ARE ENGAGED DIFFERENTIAL. Your VSC light should come on also, does on mine.

Only run the differential on loose type ground only and shouldn't drive over 60 mph while in 4hi on these types.

The AWD models you can go over the 60mph.

 

[JB.]

H

...it says you can drive in H4 with a unlocked differential on regular roads. Is this safe to do? Would this be considered full time 4x4 while in H4?

Yes, that's full time 4wd. If you have any doubt about whether you can drive that way, consider the V8 4wd 4runners. They have no 2wd option, so they do it all day, every day.

 

[svndedlysyns]

Thanks for the responses. I dont know much about 4x4's but from everything the manual said i could do that article said the opposite. Thats great news. Does anyone know the difference in mpg between H4 and H2? Is there really more wear and tear in 4wd high all the time?

 

[BlackWorksInc]

Thanks for the responses. I dont know much about 4x4's but from everything the manual said i could do that article said the opposite. Thats great news. Does anyone know the difference in mpg between H4 and H2? Is there really more wear and tear in 4wd high all the time?

Nothing significant in terms of wear and tear from what I have seen. Fuel economy suffers maybe a 1mpg hit? Its not that much different than 2WD and really the detractor of the economy hit is probably some parasitic loss as power is transferred through more sections of the drive train and the V6 not having as much lower end torque as the V8 (still not sure why the V8's never got 2WD, not that I would really use it to be honest.)

The transfer cases between the Part-Time 4WD V6 and the Full-Time 4WD V8's is simply the lack of a 2WD mechanism (basically a shift fork and a shorter shift rod). The cases are exactly alike, the other difference is that the front clamshell (a term used to describe the front differential assembly)in the V6 is slightly smaller than the V8's and uses an ADD (Automatic Disconnecting Differential) to enable 2WD mode.

4Hi in both V6 & V8 models is identical and thus can be driven like any normal vehicle with the CDL (Center Differential Lock) disengaged.

In both cases the front and rear axles will still be spinning and the internal gears will still be spinning even in 2WD (in the case of the V6), but the front pinion shaft will not spin and the transfer case shouldn't spin in 2WD mode. But to be honest these transfer cases have been pretty reliable, the biggest issue we see is that the ADD & 4WD Actuator located on the transfercase seize up from lack of regular use which tends to be a costly replacement if it gets bad enough.

 

[c_mack9]

Second question: in the owners manual it states you should drive in 4 hi in a unlocked differential for atleast 10 miles a month to keep the front drive components lubricated. And how many people actually do this. Should i take this bit of information seriously?

Yes, you should take that suggestion seriously. I recently bought one from an woner that didn't take it seriously (more like didn't know that suggestion exists) and 3 weeks in the shop totaled up over $3000 and I'm an employee! Use it or lose it. I certainly plan on evercising my actuators from now on. If yours is currently working, engage the 4wd every now and then to keep it working. Congrats on your new truck, they're one of the best vehicles ever made.

 

[cmpcmp123]

Third question: Does it seem like the unlocked and locked differentials signs should be opposite. When i see the x on the sign it seems to me that says unlocked. While the straight line would be locked in my mind.

Interesting question. My thought is that the "X" is supposed to be over the central differential; indicating that it is now not operational; locked.

 

[JB.]

Is there really more wear and tear in 4wd high all the time?

None to speak of, it's just distributed differently.

Does anyone know the difference in mpg between H4 and H2?

Can't be much. If you compare various brochures, the difference between the dedicated 2WDs and the 4WDs ranges from 0 to 1 (due to rounding), so call it 1/2 mpg. BUT, that's a comparison that factors in the extra weight of the 4wd hardware. What you're asking about is just the drive train loss since you're already hauling around the extra weight. Let's call the weight and drive train losses equal factors (I suspect when netted out, weight matters more). That gives us an estimated loss of .25mpg for running around in 4wd (AWD) mode.

Knowing that, you might be hard pressed to take it out of 4wd. The handling and highway tracking is sweet in AWD mode.

 

[svndedlysyns]

None to speak of, it's just distributed differently.



Can't be much. If you compare various brochures, the difference between the dedicated 2WDs and the 4WDs ranges from 0 and 1 (due to rounding), so call it 1/2 mpg. BUT, that's a comparison that factors in the extra weight of the 4wd hardware. What you're asking about is just the drive train loss since you're already hauling around the extra weight. Let's call the weight and drive train losses equal factors (I suspect when netted out, weight matters more). That gives us an estimated loss of .25mpg for running around in 4wd (AWD) mode.

Knowing that, you might be hard pressed to take it out of 4wd. The handling and highway tracking is sweet in AWD mode.

In this model it isnt okay to go over 60mpg in H4 unlocked diff so this isnt really awd is it? Here in atlanta it seems like 60 is the the slowest we go atleast on the freeways lol. So i should save the H4 for the back roads? I want to put it to use to keep it running nicely. Should i do the same on L4 also or does it use the same actuator? Or is it the same actuator but different parts in the actuator that puts it in L4?

Interesting question. My thought is that the "X" is supposed to be over the central differential; indicating that it is now not operational; locked.

I guess that makes sense too. I guess it is how you look at it. Easier for me to remember what it does that way. Thanks

 

[KidVermicious]

Thanks for the responses. I dont know much about 4x4's but from everything the manual said i could do that article said the opposite.

I spent about fifteen seconds scanning the first part of that article and spotted at least four glaring errors right away. Whoever wrote that is a clueless windbag, and you should forget everthing that article told you.

Here's the basics that you need to know: four wheel drive trucks have a transfer case that splits the output from the transmission to the front and rear differentials equally. A "part-time" four wheel drive (most older trucks, fewer modern trucks) has a RWD mode for normal driving, and some sort of selector that engages the front output for 4WD. This is the kind that people are referring to when they say you shouldn't drive in 4WD on pavement. And they're right, sort of, but it's not nearly as drastically wrong as most nervous nellies make it out to be. A "full-time" 4WD system is similiar, except it has a differential on the transfer case (you'll see this referred to as a "center diff") that lets the front and rear driveshafts spin at different speeds, just like the differential on your axle lets your left and right wheels spin at different speeds. This relieves the driveline binding that's caused when you use part-time 4WD on the pavement - a truck with full-time 4WD doesn't have that problem. Some trucks with full-time 4WD have what's referred to as a lockable transfer case differential - this provides the increased traction of a part-time 4WD system when locked (for off-pavement use) and the flexibility of a full-time 4WD system when unlocked (for on-pavement use). As a side note, some people erroneously use "full-time 4WD" and "all wheel drive" synonymously - they're not the same thing, although they sometimes behave similarly.

What you have is the full-time 4WD with a lockable center diff - Toyota calls this "multimode". You can use your 4WD up to the speeds indicated in your owners manual if you unlock the center differential, which will give you a little better traction on slick or snowy roads, and won't hurt anything if the roads are dry and sticky. The drawback to having that center differential open is that if you get in a tough spot (mud, deep snow, whatever) and lose traction with even one tire, it can start spinning and draw all the power from the other tires, leaving you stuck. That's when you use your center diff lock, which ties the front and rear driveshafts together and makes sure that power is being transmitted to the front and rear axles equally, giving you better traction.

In this model it isnt okay to go over 60mpg in H4 unlocked diff so this isnt really awd is it? Here in atlanta it seems like 60 is the the slowest we go atleast on the freeways lol. So i should save the H4 for the back roads? I want to put it to use to keep it running nicely. Should i do the same on L4 also or does it use the same actuator? Or is it the same actuator but different parts in the actuator that puts it in L4?

Personally, I would save any possible wear on the system and leave it in 2WD unless you're on bad roads and need the extra traction to be safe, in which case I don't think you'd want to be going near 60mph anyway.

When you do pop it into 4wd just to keep everything working and lubed, I'd go into and out of low range at the same time. You can safely use low range with a locked center diff on pavement, but do it at slow speeds (under 10mph) and in a straight line just to be on the safe side.

 

[Synister]

You must be below 60mph to engage (2WD-->4WD) the system...once engaged, however, you may travel at any speed you wish. You may also disengage (4WD-->2WD) the center diff at any speed. You may also lock the center diff while moving, slowly, without turning. Same goes for unlocking. You only need to be stopped and in neutral with your foot on the brake to select 4L. If you havn't gleaned this nugget already, here it is again; this system is a use it or lose one...exercise it 1x month at least and you will have little to no problems with it at all. Fail to do so and you will join the dozens who discover 8 years down the line that their actuator has seized from lack of use. Good luck, its a great system once you understand it, probably one of the most advanced ever offered on a major production vehicle.

 

[BCfish]

#3- When in 4wd,the green light will be on, in 4lo will say 4lo with it.
When the yellow 4 tire symbol comes on below the green one, YOU ARE ENGAGED DIFFERENTIAL. Your VSC light should come on also, does on mine.

Only run the differential on loose type ground only and shouldn't drive over 60 mph while in 4hi on these types.

The AWD models you can go over the 60mph.

I have to say you are wrong you can do more than 60mph you need to be at that or slower to shift into 4Hi. Plus there is no real limit to how fast you can travel in 4Hi when unlocked I used to use it all the time in bad weather on the highway and freeway never had a problem til I got my Duratracs now I use 2wd pretty much only. Unlike earlier Gens that you would never run 4Hi on pavement or high traction surfaces.

 

[having fun]

I have to say you are wrong you can do more than 60mph you need to be at that or slower to shift into 4Hi. Plus there is no real limit to how fast you can travel in 4Hi when unlocked.

:doh: I stand corrected, kind sir. Miss read obviously.
Out here in cali, don't really get/have the need to go over the 60 mark in 4h.

Good to know if I decide to run upper mid north areas.

 

[JB.]

So, to recap for you svndedlysyns:

(1) Very little mpg hit for running in full-time 4wd (aka awd mode).
(2) No extra wear and tear running that way.
(3) No speed limit running that way. Only for shifting into it.
(4) Both center diff lock and low range should be engaged once a month (or more).

The best overall guide for such questions is to remember that the V8 drive train is virtually identical except has no 2wd option.

 

[svndedlysyns]

So, to recap for you svndedlysyns:

(1) Very little mpg hit for running in full-time 4wd (aka awd mode).
(2) No extra wear and tear running that way.
(3) No speed limit running that way. Only for shifting into it.
(4) Both center diff lock and low range should be engaged once a month (or more).

The best overall guide for such questions is to remember that the V8 drive train is virtually identical except has no 2wd option.

Thanks for everyones help!! :thumb3: