explain how 4wd auto works?

[cjben]

Just making sure something isn't wrong with our 2004 and making sure I have the 4wd selector in the right position. I think it is in 4wd auto. On slippery (wet pavement,grass) surfaces and sometimes under hard acceleration on dry surfaces around corners or tight turns into parking spots,you can feel the front wheels grab and get traction. I have shifted through all the ranges,all work as they should. Is this normal? I have never owned a vehicle with this type of system,always been a manual shifter person. And if this is normal,is there any way to get just 2wd all the time? really only need 4wd about 3 months out of the year,even if the drivetrain thinks I need it more often.

 

[SlinginIron]

On my 07, I also have three selections including 4X4 auto, 4 high, and 4 low. You should be doing most of your driving in 4 auto. The vehicle defaults to rear-wheel drive unless the computer believes you are getting too much slip, then it will engage power to the front end. So, if you don't need four wheel drive and you aren't trying to do burnouts the vehicle will remain rear wheel drive. You may already know the following but, over the past 5 years people have been throwing around the terms 4WD and AWD as interchangeable. They are different systems. With 4 wd you will usually have an open front and rear differential, in 2wd (or 4 auto in this case) power goes to the rear end and follows the path of least resistance. if you (or the vehicle) engages 4wd then you will also have power going to the front end. (also usually with and open diff) So, for the vast majority of stock 4wds are really two wheel drive when the 4wd is engaged, it just happens to be one front wheel and one rear wheel. In an AWD system you have power that can freely go to any wheel (but will go to the path of least resistance) so in a reality AWD vehicles are only one-wheel drive. Now computers having to do with the engine, ABS, wheel slip, lateral G forces can "overcome" or modify the route (to which wheel) that power will go to, making it so that the power will not go to the wheel with the least amount of traction. Also limited slip, and lockers can change where your power must go to get to the ground. I hope I didn't go off topic too much.

 

[imp]

Just making sure something isn't wrong with our 2004 and making sure I have the 4wd selector in the right position. I think it is in 4wd auto. On slippery (wet pavement,grass) surfaces and sometimes under hard acceleration on dry surfaces around corners or tight turns into parking spots,you can feel the front wheels grab and get traction. I have shifted through all the ranges,all work as they should. Is this normal? I have never owned a vehicle with this type of system,always been a manual shifter person. And if this is normal,is there any way to get just 2wd all the time? really only need 4wd about 3 months out of the year,even if the drivetrain thinks I need it more often.

1) That "grab" can be a bit disconcerting, and noisy, if it is engaged rapidly on and off, due to traction/no traction conditions.
2) It is normal with this type of "4X4 AUTO" design.
3) There are several ways to defeat the 4X4 AUTO function. Using any of them will disable all 4X4 operation. One way, rather difficult and inconvenient, is to remove the front driveshaft. The other, is to unplug the harness connector at the transfer case, or more attractively, remove the 2 fuses which "feed" the "Electronic 4X4 System". Either of these last two means, will cause the PCM (computer) to detect a "fault", and cause the "O/D OFF" light to flash on and off, and/or display an icon, usually "4X4 LOW" on the dashpanel, as well as illuminate the "ABS" icon there. If you can live with a Christmas-tree like dash panel, removing the fuses is an easy way to disable 4X4 AUTO.

If you want to pursue this, let me know, and I will retrieve my wiring manual to determine the correct fuses. imp

 

[fireball 440]

You can over ride the Auto4x4 system by doing the "Brown Wire Mod", found on these forums. It should be in a sticky, if not search for it. It's a cheap fairly easy fix for the grabby front axle. Sounds like its going to break sometimes, horrible design IMO, but it is what it is.

 

[D Hook]

http://www.explorerforum.com/forums/showthread.php?t=194875

It's a long read but a good mod for what you're looking for. Some do it without the relay.

 

[eric 2004]

I have a problem with an 04 explorer. at time my back rear does not work and while driving it kinda pushes you and while stopped at a light or stop sign it jerks and try to push you and when put into park it wont stay. know at times my back rear does engage and work and there is not jerking or pushing and when u put it in park it goes in and stays put. does anyone have any idea what that could be