2005 Ford Explorer 4x4 Auto

We recently rented a 2005 Ford Explorer XLT for the weekend and loved
it for both on-road as well as light off-road 4-wheeling.

Can someone explain or direct me to a site that explains how the "4x4
Auto" setting works? I am interested in the drive train details and
what the expected lifetime is for this setting?

How reliable is the 4.0 L V6 Engine? I found it had plenty of power for
our needs.

wrote:
>
> We recently rented a 2005 Ford Explorer XLT for the weekend and loved
> it for both on-road as well as light off-road 4-wheeling.
>
> Can someone explain or direct me to a site that explains how the "4x4
> Auto" setting works? I am interested in the drive train details and
> what the expected lifetime is for this setting?
>
> How reliable is the 4.0 L V6 Engine? I found it had plenty of power for
> our needs.

From the Ford Service Manual

Four-Wheel Drive Systems —Automatic Four Wheel Drive (A4WD)

The automatic four-wheel drive (A4WD) system is an
electronic shift 4X4 system that utilizes the following
components:

-transfer case
-four-wheel drive (4WD) control module
-mode select switch (MSS)
-gearmotor encoder assembly
-electric shift motor (part of gearmotor encoder assembly)
-shift motor sense plate (part of gearmotor encoder
assembly)

Transfer Case

Motor, Electric Shift

The externally mounted transfer case shift motor, located at
the rear of the transfer case, turns the shift cam assembly.
As the shift cam assembly turns, it positions the reduction
shift fork for desired transfer case operation. An integral
position sensor in the shift motor provides motor position
information to the 4x4 electronic module.

Switch, Push Button 4x4 Mode

The push button 4x4 mode switch, mounted on the instrument
panel, allows the operator to select the 4x4 Auto, 4x4 High,
and 4x4 Low transfer case operating modes. The indicator
light, on the instrument cluster push button, will
illuminate only when the 4x4 Low position is engaged.

Switch, Brake Pedal Position (BPP)

The brake pedal position (BPP) switch is located on the
brake pedal. The switch signals the 4x4 electronic module
when the operator activates the brake pedal.

Switch, Clutch Pedal Position (CPP)

The clutch pedal position (CPP) switch is located on the
clutch pedal bracket. On vehicles equipped with a manual
transmission and an electronic shift transfer case, the
clutch pedal must be fully depressed and vehicle stopped in
order to make a range shift from HIGH to LOW, or from LOW to
HIGH.

Sensor, Digital Transmission Range (DTR)

The DTR sensor is located on the outside of the transmission
near the transmission shift cable attachment. The DTR sensor
completes the start circuit in PARK and NEUTRAL, the back-up
lamp circuit in REVERSE and the neutral sense circuit (4WD)
in NEUTRAL. The DTR sensor also sends a digital output
signal to the powertrain control module (PCM) indicating the
manual lever position (P, R, N, D, 2, 1).

Sensor, Throttle Position (TP)

The TP sensor is located on the throttle body. The sensor
provides throttle position information to the PCM. The PCM
converts the throttle position signal to a pulse width
modulated (PWM) signal, and sends it to the 4x4 electronic
module to control and adjust the transfer case clutch duty
cycle.

Sensor, Front and Rear Output Shaft Speed (OSS)

The externally mounted OSS sensors are located at the rear
of the transfer case. The sensors provide the 4x4 electronic
module with front and rear driveshaft speeds to control and
adjust the transfer case clutch duty cycle.

Sensor, Vehicle Speed Sensor (VSS)

The Anti-Lock Brake System (ABS) provides the 4x4 electronic
module with vehicle speed information to control and adjust
the transfer case clutch duty cycle.

4x4 Electronic Module

The electronic module (located behind the glove compartment)
controls the operation of the transfer case in response to
inputs from the electric shift motor, 4x4 mode switch, CPP
switch, BPP switch, DTR sensor, throttle position output
from the PCM, front and rear OSS sensors, and the VSS.

Mechanical Operation

The Borg-Warner 44-11 transfer case is available in the
Explorer (A4WD) vehicle. The transfer case transfers power
from the transmission to the rear axle, and also to the
front axle when electronically activated.

In the Auto mode, torque from the transmission is
transferred to the input shaft which, in turn, drives the
rear output shaft that drives the rear axle assembly. The
electromechanical ball ramp clutch assembly drives the drive
sprocket after the 4x4 electronic module activates the
clutch coil. The drive sprocket turns the drive chain that
rotates the front output shaft and the front driveshaft. In
the 4x4 High mode, the operation is the same as in the Auto
mode, except that the 4x4 electronic module consistently
activates the electromechanical ball ramp clutch assembly.

The high-low shift occurs when the reduction shift fork
moves the high-low collar to lock the planetary gear set to
the output shaft. Then, torque, transmitted through the sun
gear, from the input shaft, turns the front planetary gear
set assembly. The front planetary gear set assembly, which
is now engaged, provides transfer case speed reduction.

Transfer Case Functions

There are three transfer case modes, Auto, 4x4 Low, and 4x4
High. Neutral is only available as a dealer installed
option.

Control-Trac Function

The Control-Trac transfer case uses an electromechanical
clutch assembly to control torque to the front wheels. In
the Auto mode, while at rest and under cruising conditions,
the 4x4 electronic module activates the transfer case clutch
at a minimum level. This allows for the slight difference
between the front and rear driveshafts which occurs normally
when negotiating a corner on dry pavement. Under any of the
following conditions, the 4x4 electronic module will
increase the torque sent through the clutch to the front
wheels in order to prevent or control slip.

Slip is detected (by monitoring the front and rear OSS
sensors in the transfer case)
Throttle position (by using the throttle position signal
from the PCM)

Range Function

NOTE: At zero throttle, the duty cycle remains low.

In the 4x4 Low Range, with throttle input, the transfer case
electromechanical clutch locks the front and rear
driveshafts for maximum 4x4 traction. The transfer case
shift motor rotates the shift cam to move the reduction
shift fork to the 4x4 Low range position. This low range
shift, accomplished through a planetary gear set, changes
the torque to the driveshaft from 1:1 to 2.48:1 ratio.

In the 4x4 High Range, with throttle input, the 4x4
electronic module signals the transfer case
electromechanical clutch to lock the front and the rear
driveshafts for maximum 4x4 traction. Never use the 4x4 High
range or the 4x4 Low range when driving on dry or merely wet
pavement. Use the 4x4 High range or the 4x4 Low range only
for driving off-road or in severe winter weather.

Ed

4x4 auto sends power to the rear wheels with advancetrac enabled. If rear
tires lose traction, power is dynamically sent to the front wheels.

4x4 hi sends power to all four wheels with advancetrac enabled

4x4 lo sends power to all four wheels with advancetrac DISABLED.

Wow dude this expanation is awesome. I thought I new alot about my trucks
4wd. Thanks to your explantion I think I know where to turn for my OD
blinking light problem, not to mention I know a hell of alot more about
the inner workings of my transfer case and drive train.

Thanks,

Rick