What is the difference between full-time and part-time 4x4 systems?
Full-time 4x4 systems utilize a center differential, which enables the front and rear driveshafts to turn at different speeds, thereby allowing engagement on dry surfaces for normal driving conditions. A part-time system does not employ a center differential and locks the front and rear driveshafts together. With a part-time system, 4x2 mode should be used during normal driving conditions and 4x4 mode is to be used only when off-road or on wet or slippery surfaces.
Why can't you use a part-time 4x4 system on dry surfaces?
Part-time 4x4 systems effectively lock the front and rear driveshafts together, forming a single driving unit that does not allow for differential action between the front and rear driveshafts. Driveline noise and binding (Crow Hop) may occur when operated especially on dry surfaces or in turns. This binding can lead to heat buildup and early part failure.
Why does "Crow Hop" occur?
When a vehicle turns, each wheel rotates on a different radius to the turning circle, thus traveling at different distances and speeds. If the vehicle's front and rear axles are locked together and are turning on dry surfaces, the difference in wheel speed sometimes results in driveline binding that is released with a "bang" or vehicle "shudder" when one of the tires loses traction.
Can I shift into 4x4 High-Range at any speed?
On Jeep® 4x4 systems, shifting into 4x4 High-Range can be done with the vehicle stopped or in motion. If the vehicle is in motion, shifts can be made up to 55 mph (88 km/h).
How long can I drive in 4x4 High-Range?
With a part-time system, prolonged driving in 4WD high-range is recommended only for wet, loose, or slippery road surfaces. With a full-time system, you need not worry about switching to 2WD mode when road surfaces improve.
How fast can I drive in 4x4 High-Range?
You should not go faster than road conditions permit.
What is 4x4 Low-Range?
"4x4 Low-Range is a mode specifically designed for temporary use when additional traction and low-speed maximum pulling power is desired. Front and rear driveshafts are locked together and engine power is sent through another set of gears to multiply torque. Avoid attempting to engage or disengage Low-Range with the vehicle moving faster than 2 to 3 mph (3 to 5 km/h) and do not use this mode for normal driving."
Can I shift into 4x4 Low-Range at any speed?
No. With the vehicle rolling at 2 to 3 mph (3 to 5 km/h), shift an automatic transmission to Neutral or depress the clutch pedal on a manual transmission. While the vehicle is coasting at 2 to 3 mph (3 to 5 km/h), shift the transfer case lever firmly through Neutral and into the low-range position.
How fast can I drive in 4x4 Low-Range?
Do not exceed 25 mph (40 km/h).
Can I shift into 4x4 Low-Range when stopped?
Shifting into or out of 4WD low-range is possible with the vehicle completely stopped, however, difficulty may occur due to the teeth of the gears not being properly aligned. The preferred method to engage the low-range is to slow down to 2 to 3 mph (3 to 5 km/h) and put the transmission in Neutral. While still moving forward, move the shift lever firmly into the four-low position. Then return the transmission to the desired gear. Refer to your owner's manual for detailed instructions.
What if I never use the Selec-Terrain
In AUTO mode, the vehicle will automatically select the correct drive system for the condition it senses.
Does the vehicle need to be parked or moving to operate the Quadra-Lift® suspension or Selec-Terrain® system?
The vehicle can be in either Park or moving to operate the Quadra-Lift® air suspension or Selec-Terrain® settings. When the vehicle is moving, the driver can manually select the appropriate height setting of the Quadra-Lift system or have the vehicle select the optimal setting automatically. Drivers can also use the Selec-Terrain® control dial to optimize drivetrain and brake control systems for a specific terrain. There are speed thresholds for the various Quadra-Lift height settings. For instance, the driver can make the request for Park mode at speeds below 12 mph. The system begins lowering to Park height when the vehicle speed is below 6 mph. This feature ensures that Park height is achieved prior to exiting the vehicle. Off-road heights are also speed-limited on the upper end to maintain ride comfort objectives.