NOTICE
Never exhaust air from the suspension while
driving. When the air is exhausted, the suspen-
sion will not absorb road shocks, and compo-
nents may be damaged.
A red LED in the switch is illuminated when the sus-
pension is deflated.
Aerodynamic Height Control
NOTICE
The aerodynamic height control (AHC) switch
should not be used to raise the vehicle in an at-
tempt to drive over objects in the road, as doing
so will result in vehicle damage.
AHC reduces ground clearance by approximately 1
inch (2.5 cm) at highway speed. If this reduction of
ground clearance is determined to be problematic,
such as a construction zone or poor road conditions,
AHC may be disabled. Pressing the AHC switch,
shown in
Fig. 4.25, disables aerodynamic lowering of
the vehicle. The switch should be activated well in
advance in order to avoid potential vehicle damage
in these types of road conditions.
ECAS Dash Switches
Vehicles with Electronically Controlled Air Suspension
(ECAS) may be equipped with either dash switches
or a remote control unit, not both. See
Figure 4.26
and Table 4.1.
LOAD XFER (Load Transfer)
This switch controls the ECAS manual load transfer
function by adjusting suspension air pressure. Use
this function to minimize wheel slippage in road con-
ditions where traction may be a concern.
The ECAS load transfer feature applies the maxi-
mum available vehicle load on the drive axle, up to
the maximum allowable limit, determined by the
gross axle weight rating (GAWR). In bobtail or with a
loaded trailer less than the GAWR, the tag axle sup-
ports a negligible load while the drive axle supports
nearly the full weight. Above the GAWR, the drive
axle is loaded with approximately the maximum al-
lowable load and the tag supports the remainder.
Load transfer mode can be deactivated by holding up
on the dash switch for 4 seconds. Load transfer
mode will automatically deactivate when the vehicle
reaches 45 mph (72 km/h).
For vehicles equipped with the ICU, when load trans-
fer mode is active, "Load Transfer" will display in the
message field of the driver display. See
Figure 4.27.
f61134209/15/2016
SUSP
HGT
LOWER
NORMAL
Fig. 4.24, Air Suspension Height Control Switch
f61152709/11/2018
AERO
OFF
A
Fig. 4.25, Aerodynamic Height Control Switch
f61147311/16/2016
1
2
LOAD
XFER
1. Load Transfer 2. Suspension Height
Fig. 4.26, ECAS Dash Switches
Driver Controls
4.13
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