What is 4X4 Auto?

[Donner]

Mine rolls smooth as silk! I only notice a change when I have to stop to do the 4lo thing in Neutral.

 

[GJarrett]

OK, to recap (seeing as I started this thread), this is what I've figured out from what I have read here and elsewhere:

4WD Auto = 2WD unless truck detects slippage between front and rear wheels. When slippage is detected, truck starts engaging 4WD clutch in transfer case on and off quickly to send power to the front wheels as well. Clutch is cycled instead of just engaged continuously to allow for front wheels to travel further in turns on dry pavement without binding up the driveline, due to a lack of center differential. Duty cycle (time clutch engaged vs time clutch disengaged) varies - with lots of slippage between front/rear wheels, clutch spends more time engaged. As traction improves, clutch spends more time disengaged.

Does that sound right?

Okay, I'll try one more time and then quit. No that is not right. We confirmed that nine years ago.

I was hoping the prior link I provided, along the first answer by heathmo when he talked about seeing the LED light on his brown wire mod glow dimly when in 4 auto, would clarify that when in 4auto there is in fact some power sent to the front even without rear wheel slippage. It is not full power and with a stock setup you won't be able to tell it, but it is there.

I have 35" tires and a front locker with the brown wire mod to disengage the power to the front. Do you know why I HAVE to have the brown wire mod? Because I can guarandamntee you that in 4auto on hard pavement, I can feel the front locker engaging. The only way it is engaging is because power is being routed to the front axle, even on dry hard pavement with no rear wheel slippage. I HAVE to turn off power via the brown wire mod to prevent my front locker from engaging while in 4auto.... while in 4auto it is a real struggle with my steering wheel fighting those big locked tires trying to push me straight through any turn. If 4auto was not sending on power to the front, there would be no need for me to turn it off. Once I flip the brown wire mod switch to disengage the transfer case, it drives normally as in 2wd.

I suppose the bottom line is that it doesn't matter how it works and goes back to another point that I think shadowless was trying to make.... it can be treated as automatic so you don't have to worry about how it really works; that's the whole point. Just use it.

 

[Cozmik]

Mine rolls smooth as silk! I only notice a change when I have to stop to do the 4lo thing in Neutral.

Mines very smooth too. Just that I can tell when the auto does its thing. Steering gets a bit heavy.

 

[Cozmik]

Just went to page 1 and clicked the link. Read Tom's post. VERY informative. Learn something new everyday!!! I had no idea that there was a 95/5% split and that there was almost constant power to the front.

However it works and whatever you want to call it, it works well.

 

[gijoecam]

Okay, I'll try one more time and then quit. No that is not right. We confirmed that nine years ago.

I was hoping the prior link I provided, along the first answer by heathmo when he talked about seeing the LED light on his brown wire mod glow dimly when in 4 auto, would clarify that when in 4auto there is in fact some power sent to the front even without rear wheel slippage. It is not full power and with a stock setup you won't be able to tell it, but it is there.

That's where theory and reality diverge, and has also been explained repeatedly in the last 9 years...

Yes, the light glows, even in 4auto when stopped. However, the intensity of the light in a lighted switch for the BWM does not indicate the amount of power being sent to the front wheels; it's only an indication of the duty cycle of the transfer case clutch coil. In reality, we've seen that the front driveshaft is not linked to the rear when the TCCC is at minimum duty cycle. There also does not appear to be a significant (or perceivable) difference in the 'gray area' between minimum and maximum duty cycle when the system activates it in 4auto. In reality, the TCCC is either locked or unlocked, similar to the way the clutch on an AC compressor works.

So, while the light may glow dimly, it's not a direct indication of whether or not the case is locked. At any rate, when slippage starts, it's a nearly instantaneous (and automatic) application of 4 wheel drive... it's still not all wheel drive.

I have 35" tires and a front locker with the brown wire mod to disengage the power to the front. Do you know why I HAVE to have the brown wire mod? Because I can guarandamntee you that in 4auto on hard pavement, I can feel the front locker engaging. The only way it is engaging is because power is being routed to the front axle, even on dry hard pavement with no rear wheel slippage. I HAVE to turn off power via the brown wire mod to prevent my front locker from engaging while in 4auto.... while in 4auto it is a real struggle with my steering wheel fighting those big locked tires trying to push me straight through any turn. If 4auto was not sending on power to the front, there would be no need for me to turn it off. Once I flip the brown wire mod switch to disengage the transfer case, it drives normally as in 2wd.

Humor me: The next time you have the front end in the air, with the key off, spin the front driveshaft. Then, with the key on and engine idling(BWM LED glowing dimly) try to spin the front driveshaft. On mine, there was no discernable difference. i.e. I could still spin the front driveshaft by hand. That tells me that, at minimum duty cycle, there is no discernable force applied to the front shaft. I can't vouch for what yours is doing, having not been there to monitor the GEM PIDs while it's doing it, but I would wager a bet that the TOD relay is at something greater than minimum duty cycle when the locker engages, and that's why the BWM works to stop that from happening.

I suppose the bottom line is that it doesn't matter how it works and goes back to another point that I think shadowless was trying to make.... it can be treated as automatic so you don't have to worry about how it really works; that's the whole point. Just use it.

Agreed... but just because it works automatically still doesn't make it all wheel drive. Mechanically-speaking, it's not driving all the wheels. It drives the rear output and locks the front output to it if necessary and on-demand... just the way a part-time 4 wheel drive unit does, but with fancier controls. All wheel drive systems drive all four wheels all the time.... It's a different mechanical principle all together.

 

[CDW6212R]

Auto 4wd is a passive AWD system in theory; obviously it's not the same TECHNICALLY, but in theory it is.

This thread was great until someone abused the term AWD and linked it to 4WD. Several others have done the same thing, dozens in the past, and countless more will in the future.

I suggest that everyone stick to the proper terms, and not confuse others by mixing meanings.

It is very hard to explain to a novice that 4WD must never be used on dry pavement. What do you think happens when you confuse them more by posting that A4WD is some kind of AWD?

Simply use other more appropriate terms to describe A4WD, like those posted all throughout this thread. Do not suggest that it is like AWD, or some part time AWD, those are your opinions, and they are very harmful to the understanding of a novice. Keep the definitions clear please. Regards,

 

[Donner]

4x4 Auto, I use it every time I drive - I have no choice. Others use the BWM so they don't have to deal with it, they have 2wd because of that.

OPINION: 4x4Auto, you don't have to use it, BWM. But if you do, you decide how it rides - simple enough.

Brown Wire Modification.

 

[Albino 94LTD]

This thread was great until someone abused the term AWD and linked it to 4WD. Keep the definitions clear please. Regards,

That would have been ME in post #4 describing the difference between the Control-Trac system and the Advance-Trac system. I thought it was relevant since his Limited and my Aviator were of the same model year and they might have the same type of system with the exception being a transfer case instead of a center diff.

Sorry to cause such confusion

I am curious if an '03 does apply braking force and engine power management even if it's not AWD.

 

[Donner]

I have to confess, I too abused the term AWD and linked it to 4x4auto. Guilty as charged... There's no confusion, it's all good... except I didn't ABUSE, I CHOSE to describe it the way it BEHAVES in my opinion... And all these people that don't drive 4x4Auto telling other members what to say and what not to say - WE drive them and have every right to present our opinion. And the manual says 4x4auto is power to all wheels - I'm good with that. But it, IMO, behaves like AWD.

 

[CDW6212R]

I know Donner, but remember that these forums are full of novices etc. who are trying to learn what so many of these terms mean. They read AWD and along with the 4WD system they easily confuse how the two differ.

The later Explorers, and Aviator, had both AWD and 4WD transfer cases available. The Advance Trac and stability control stuff were separate options, not part of the transfer case systems. Ford constantly confuses even the best enthusiasts, we just try to keep up with the changes.

 

[Donner]

Very true... Understood.