HolidayJones,
This might be helpful.
Info from the 2005 manual:
• 4L (4X4 LOW) provides mechanically locked four-wheel drive when
extra power at reduced speeds is required. The “4X4 LOW” light will
illuminate in the instrument cluster when this position is selected.
This position is not recommended for use on dry pavement. Use this
position for off-road low-speed operation or when extra power is
required, such as climbing steep grades, going through deep sand or
pulling a boat out of the water.
Note: If your vehicle is equipped with AdvanceTrac with RSC, the
AdvanceTrac with RSC system will automatically turn off the stability
enhancement feature when you shift the Control Trac A4WD system into
4L (4X4 LOW). The brake traction enhancement feature will still be
enabled.
The AdvanceTrac with RSC stability enhancement system can be turned
off manually by pressing the AdvanceTrac with RSC button (refer to
AdvanceTrac with Roll Stability Control (RSC) Stability
Enhancement System in this chapter) while operating in 2H, A4WD or
4H while driving in deep sand, very deep snow or more strenuous
off-road maneuvers. This will disable the engine management feature,
allowing the vehicle to maintain full power and enhanced momentum
through the obstacle.
AIR SUSPENSION SYSTEM (IF EQUIPPED)
If your vehicle is equipped with four-wheel drive and you shift into 4WD
LOW, the air suspension will not move to it’s lowest position; instead, the
ride height is raised above the normal ride height position (at speeds
below 35 mph [56 km/h]) to improve ground clearance.
If a load is added to, or removed from the vehicle, the load leveling
feature of the air suspension system will adjust the suspension to keep
the vehicle at a constant level.
When exiting the vehicle, the air suspension will automatically lower the
vehicle to its lowest height to provide easier exit. You may hear a buzz or
click from the air suspension system when the ignition is turned off. The
air suspension system will stay active for 40 minutes after the ignition is
turned off to accommodate any load changes. (The air compressor may
run when the vehicle is off; this is normal.)