how do we drop the air suspension when dropping a trailer?

You can buy them from the dealer. I bought one for my trk.. Not trying to be a smart arse..

 

I have found the manuals that I need/want. And it's cost my nothing so far.

 

Rear Air Ride Suspension
CAUTION
The vehicle must not be operated on the road
without air in the suspension air bags. Failure
to observe this will result in ride degradation and
suspension damage.
Rear Air Ride Suspensions automatically adjust to different loads
to maintain constant frame height. The system maintains vehicle
ride quality and driver comfort.
Rear Air Suspension Air Dump
This feature also allows the rear of the vehicle to lower several
inches for trailer attachment/detachment.


The system is controlled by the two position
SUSP/DUMP switch with an indicator light in the
DUMP position. This switch controls solenoids, which
direct air to the suspension dump and height valve.
When the SUSP/DUMP switch is in the DUMP position
andthevehiclespeedisbelow5mph(8km/h),air
supplied to the rear air suspension is released,
lowering the frame for loading.
Placing the switch in the SUSP position causes air to fill or remain
in the air suspension for proper operating ride height.
The SUSP/DUMP switch will operate the IROS system only
if the ignition switch is in either ACC or ON positions and the
air tanks have sufficient pressure to fill the suspension. When
the ignition switch is turned off, power to the solenoid will be
removed, therefore, the suspension will remain in the state last
set by the SUSP/DUMP switch.
NOTE:
The suspension will dump when the ignition switch is in
the either ACC or ON position, but will only fill when the ignition
switch is in the ON position.
NOTE:
The SUSP/DUMP switch functions will be inhibited
by either a Traction Control or ABS event. In either event for
either SUSP or DUMP operation, the ASD switch will have to
be manually recycled after the event has passed in order to
complete the operation

 

The above is straight from a manual i found .

http://www.crengland.com/content/servicecenter/pdf/prostar.pdf

The power off google.

 

http://www.youtube.com/watch?v=DAL-98d5FFI&list=UUBYGB7ww88lnDP9Fkv0m2GA&index=11

 

Same here, when my brother bought his truck, no manual.

 

Did the OP find it , or if his truck has one?

 

Some trucks come with them, some don't... When we leased we got a company spec truck (less $$ per week) and it does NOT have a bag dump... Pain in the back when others don't drop the landing gears all the way, then drop their bags... Puts the nose too low, or they drop the gear all the way down and then pull out, the nose is too high!! Yeah... There's no pleasing me

 

How do you drop the air you ask,just get out and poke the bags with a sharp object.That should work.