I need to troubleshoot the air suspension. Looking for tips/reassurance. The light on the button stays lit, no compressor action. Pushing button changes nothing (front or hatch accessory inflator). Ride height is appropriate so bags seem to be holding air. How do I start to troubleshoot this? Was thinking about taking air bags out and hooking up to schrader valve to test bags first, then trying compressor next. Ride height sensors seem to be secure and working. Has anyone ever encountered where the ride height is just a fixed height but the compressor doesn’t respond? If the bags were leaking would it be sagging in the back?

 

As you mentioned the right height is correct, then I would suspect there's no need for the compressor to come on. You can test it by turning the key on and having two or three people putting all their weight on the back, and then wait about 15 or 20 seconds and it should kick on. Or loosen a fitting and bleed the air off, then turn the key on and wait. Relays and fuses are always advisable to check first. I always carry a couple extra relays on hand. Makes it easy to test a relay by simply swapping it out with a known good one.

 

If the air has bled off it will sag. I see one that has been parked for some time and the rear suspension is sagging really low.

 

Just checking:-

• tire inflator needs the engine running in Park.
• extended ride-height (+2") the doors have to be closed, engine running and vehicle speed < 40mph

 

The Tire Inflator LED and Switch are wired directly to the AS module and are independent from the Ride Height Switch wiring i.e. no common wires, no common grounds.

Is there any history?.

• this a new vehicle to you?
• has the AS just started doing this and was fine before?
• Are the any MIL lamp, DTCs or warning messages?

If the AS Unit is not functioning you are lucky the height remains OK but typically you will get and error code if something is wrong.

Check the fuses:-

1. HVAC/ECAS (Underhood)
2. VSES/ECAS (Underhood)
3. 4WD (Left Of Dash)

Inspect the 16-Way connector wiring and pins linking the main harness to the AS unit, Serial Comms is on Pin K (Dark Blue White = Main Body, Yellow on the AS Unit)

If there's a problem with the Serial Comms and the battery was disconnected, the BCM will assume there is no AS Unit installed (this may true if there's a fuse problem)
If the AS Unit was reconnected after the battery was reconnected again the AS Unit may not be recognized.

 

This is a new to me vehicle. I did not know anything about the AS when I bought it (no error codes). When I started messing around with the dash button and the tire inflated button I realized there was no response from the compressor. I still need to interrogate the check engine with a reader.

will check these fuses and the relay

thanks

 

Something quick, try disconnecting the battery for a couple of minutes, then reconnect, you may find you get the message "Service Air Suspension"

 

curious to know if there are any updates or feedback on this?

 

Fuses and relay are all good. Inspected the connection at the compressor, did not check pins with multimeter yet to see if there is power to the compressor

 

DId you try disconnecting the battery?

This is important as the BCM checks for AS presence on battery reconnect and remembers this condition. Of all the remedies were battery disconnect is advised, this one really is significant.