rwmorrisonjr

The 99-2000 4Runners with the Multi-Mode system (AWD) had the center locker switch integrated into the 4x4 lever, which moves in a "J" style. If I remember correctly, it works in the following sequence:

-Lever in 2H= 2WD
-Pull shifter down to 4Hi= 4Hi, open center diff (AWD)
Dash Indicator: 4 green wheel lights
-Pull shifter down, move to right to 4Hix= 4Hi, locked center diff (4x4)
Dash Indicator: 4 green wheel lights, orange center diff light
-Push shifter up one notch to N= Neutral, drivetrain disconnected from powertrain
Dash Indicator: all lights flashing, red "AT/P" light on
-Push shifter up one notch to 4Lo: 4Lo, low range 4x4, locked center diff
Dash Indicator: 4 green wheel lights, orange center diff light

Rear Locker: Must be in 4Lo, truck moving <5 mph. Push button labeled "RR Diff Lock", listen for clicking from rear. red "RR Diff Lock" light on dash will flash, then go solid.

2001-2002 Models: Replaced this system with three position 4WD shifter, eliminated rear e-locker in favor of ActiveTRAC/VSC traction control system, a la JGC, Land Rover & 1998+ Land Cruisers.

-Lever in H= 2WD. VSC, ActiveTRAC engaged
-Push 4WD button in= 4Hi, open Center diff (AWD). VSC/ActiveTRAC engaged
Dash Indicator: 4 green wheel lights
-Push Center Lock dash button ([-x-]): 4Hi, locked center diff (4x4). VSC disabled, ActiveTRAC enabled
Dash Indicator: 4 green wheel lights, orange center diff light, amber "VSC OFF" light on dash.
-Push lever up one notch to N= Neutral, drivetrain disconnected from powertrain
Dash Indicator: all lights flashing, red "AT/P" light on
-Push shifter up one notch to L: 4Lo, low range 4x4, locked center diff. VSC disabled, ActiveTRAC enabled
Dash Indicator: 4 green wheel lights, orange center diff light, amber "VSC OFF" light on dash

The center diff is incorporated into the main transfer case and acts like the one on the 1998+ LC's which the system was transferred from. It allows the truck to operate in 4WD mode on dry & wet pavement and prevents the "wheel kick" associated with making tight turns (read: parking lots) with a part-time 4WD system. Locking the center diff turns the system into a "true" 4x4 system, transferring equal power to both the front & rear drive systems.

I really hope this clears up the confusion about the differences between the two variants of the MultiMode 4WD system used on the 3rd Gen 4Runners. Also, before anyone asks, in 99-00, ONLY the LIMITEDS had the MultiMode system with optional VSC, while the base & SR5's had the part-time system. In 2001-2002, the MultiMode became standard on all 4Runners, along with VSC & ActiveTRAC, and survives to this day.

Mystickal

In most situations, the poster was not correct. What IS correct is that when the differentials are not locked, both wheels receive equal torgue. So, if both tires have equal traction, they both get power. This can be proven by lifting up the drive wheels with a jack and pressing down on the gas. Since both driven wheels have equal traction (none!) they will both spin.

The reason for this is simple: When a vehicle turns, the wheels on the outside of the turn have a longer turn radius than the wheels on the inside of the turn. Therefore, the outer wheels must spin more than the inner wheels. With a locked differential (both wheels turning at the same speed), this can't happen. Usually the vehicle will respond with a jerking motion and/or tire slippage. If done repeatedly, this will result in increased wear on the vehicle (especially the tires).

If the amount of traction that each wheel has is not equal, the wheel with the least amount of traction will spin. Since each wheel receives equal torque, and it takes A LOT less torque to move a wheel that is off the ground (or on ice) than it does to move a wheel that actually has traction, the tractionless wheel spins. Note that even though only 1 wheel is spinning, BOTH wheels are receiving the same amount of power.

For more info on how a differential works, go here. Good pictures that will show you exactly what is going on inside there.

~Bill