You will need a voltmeter to check the height sensors on the front. They operate on a 5 volt scale. You can detach the lower mount of the height sensors, and slide them in and out while watching the voltage. You should see a smooth change in voltage, from .5v when extended to 4.50 volts when compressed.
Here is a diagram showing how to connect the voltmeter (the height sensors must be plugged in, so you will need to backprobe the connector or pierce the insulation of the wires with a pin to make contact with the wiring. I prefer backprobing so as not to damage the wiring insulation. But if you do use a pin to pierce through, you can seal up the hole with silicone afterwards. Backprobing is done by inserting a paperclip through the back side of the connector so it goes down in and contacts the terminal inside.
You don't need 2 voltmeters, I was just trying to show how it hooks up between pins 1 and 2 the same way on each side.
You can test the solenoids by unplugging them and running power and ground to them via jumper wires. Power is pin 1, ground is pin 2, use the diagram above to see the wire colors. The module supplies them with 12 volts to open them. Don't leave them connected to power too long to prevent overheating them. Once they are open, do your relay switch trick, to get the compressor to run, and if the solenoids and lines are not clogged, the front should raise. You may need to remove the solenoids and verify they flow or not, and check the air line from the compressor to the front solenoids.
The four wheel air suspension system is comprised of the following components:
- service switch
- control module
- two front height sensors
- one rear height sensor
- compressor and drier assembly (includes vent solenoid)
- air lines
- front and rear air spring and shock absorber assemblies
- four air spring solenoids
- compressor relay
WARNING: The service switch for the air suspension system must be shut off prior to hoisting, jacking or towing an air suspension vehicle. This can be accomplished by turning off the air suspension switch located in the jack storage area in the rear of the passenger compartment. Failure to do so may result in unexpected inflation or deflation of the air springs which may result in shifting of the vehicle during these operations.
WARNING: Do not remove an air spring under any circumstances when there is pressure in the air spring. Do not remove any components supporting an air spring without either exhausting the air or providing support for the air spring to prevent vehicle damage or personal injury.
Air Suspension Pneumatic Diagram
|Item ||Part Number ||Description |
|1 ||5319 ||Air compressor and drier |
|2 ||5B322 ||Air line T-fitting |
|3 ||5B321 ||Air line union |
|4 ||— ||Air line Y-fitting |
|5 ||18945/5311 ||Air spring and solenoid |