Functional Check for ILAS III Valve - Manual and Automatic
Refer to Figure 3 for proper setup of the test equipment. The line connected to Port 11 will require
regulated air. Ports 21, 22 and 23 will need to be plugged and supply air will need to be connected
to Port 1. For on the vehicle testing, leave all Ports connected except for Port 11, a regulated pressure
line will be needed and the Height Control Valve (HCV) line will need to be pluggged.
WARNING: Wheels should be blocked and proper support of the vehicle should be used.
Lift axles will cycle up and down during Functional check. Extreme caution should be
used when testing the ILAS III on the vehicle.
1. Connect regulated air pressure line to Port 11. connect the air switch and gauge to the test port
as shown in Figure 3. A test port adapter fitting may need to be installed into the test port to
properly connect the gauge.
2. Set the regulated pressure to 80 PSI entering Port 11. Check all ports with a soapy water
solution for air leaks.
3. Close the air switch connected to the test port. Pressure can be seen building in the test port
via the test port gauge. the test port gauge shows you the response of the valve. The test port
gauge will be used to identify the pressure settings of the valve.
4. As the pressure increases in the test port gauge watch and listen for the exhaust of the valve
when the Ps1 setting is triggered. Caution: If the valve is on the vehicle, the axle(s) will drop
when Ps1 is reached. Factory setting is approximately 62 PSI. For the manual valve, the air
switch can be used to release pressure and to repeat Steps 1-4. For the automatic valve,
proceed to Steps 5 and 6.
5. Once the Ps1 has triggered and the test port gauge has equalized to Port 11 gauge, the
pressure on the regulated gauge can be turned down to 10 PSI. Do not open the air switch
until Ps2 has triggered and the gauges have equalized.
6. The pressure in the test port gauge will begin to decrease slowly, watch and listen closely
again for the exhaust of the valve when the Ps2 is triggered. Caution: If the valve is on the
vehicle the axle(s) will raise when Ps2 is reached. The factory setting is approximately 20 PSI.
Ps1 Adjustment for ILAS III Valves - Manual (90555293) and Automatic (90555288)
IMPORTANT NOTE: The Ps1 setting of the valve must be lower than the fully loaded
airbag pressure of the suspension with the lift axle in the up position. If this guideline
is not followed, the Ps1 will not trigger and the lift axle will remain in the up position.
1. The ILAS III Ps1 setting is factory set at 62 PSI. If adjustment is necessary, use the adjustment
wrench shown in Figure 4. Turn in the adjustment nut (under the yellow cap) until it stops, then
back nut out four turns. DO NOT TORQUE! Repeat Steps 1-4 of the Functional Check to verify the
Ps1 setting is now above the desired new setting for Ps1. The Ps1 has a setting range of 45 PSI
minimum to 75 PSI maximum. (See Figure 5 for adjustment range.)
2. Connect a regulated air pressure line to Port 11. Connect the gauge and the air switch to the test
port as shown in Figure 3.
3. Set the regulated pressure in Port 11 to the desired
Ps1 setting. Allow the test port gauge to equalize
to the regulated pressure in Port 11 (may take
several minutes).
4. To change the Ps1 setting accurately, the test port
gauge must equal the regulated pressure gauge
of Port 11 (EXTREMELY important for precise
setting of the valve). Very slowly back the
adjustment nut out (turn to the left) until the
exhaust of the valve is heard. Caution: If valve is
on the vehicle, the axle(s) will drop. Stop
adjustment when exhaust is heard. The valve is
now set to the regulated pressure supplied to
Port 11. Repeat Steps 1-4 of the Functional
Check to verify that the Ps1 setting is at the
desired pressure setting.
Figure 4
Figure 3
Figure 5
