Suspension warning/misc compressor connection?

[Bowtied]

So I took the z55 compressor off to inspect it due to the “service suspension” warnings I’ve had since I bought my LTZ used -
and noticed the air line to the left rear shock had been disconnected and was too taught to give it some play.
Worked that a little bit with those hose junction inside the box, and was able to get the rear left shock as well as the right one working.
When I mean working, I mean the bladder fills with air - I don’t see any change in ride height adjustment though. How does that work?
Also, inside of the box is this tiny little zip tied plastic o ring with a connection on the end that looks disconnected and I cannot find any harness that looks like ti wouldnt connect to it (enclosed photo) -anybody know what this is/does?
Also what controls the ride height and what could still be throwing a fault code if both rear shocks fill with air and the pump works?

 

[Joseph Garcia]

There are 4 ride height sensors, one at each wheel. They are seen by looking for a 3-4" rod (1/8" in diameter) with one side connected to the control arm and the other side connected to a rotating module with a variable resistor inside that is connected to the frame. There is an electronic suspension control module mounted on the frame above the spare tire, that has wires running to each of these ride height sensors, and it monitors the height of each corner of the truck by measuring the resistance in each of the ride height sensors. The electronic suspension control module then activates the compressor as needed to maintain the level of the truck by adding or removing air from the rear shocks.

You should have a rubber line running from the compressor up to a location near the gas filler line inside the quarter panel that has a filter on the end, which is where the compressor receives its fresh air supply. Make sure that is connected. My first look at your photo suggests that this may be part of the fresh air line. Please check the inside of that connector to ensure that it has no electrical contacts inside of it, as that would suggest something else.

You state that the air bladders firm up when the compressor turns on. I suggest that you make a mixture of water and soap in a spray bottle and spray the shocks, bladders, and air lines to ensure that you have no leaks anywhere. If you see any bubbles, then all bets are off, and you will need to replace any leaking parts.

I would suspect your compressor may have issues, if you found that air line was disconnected. Being disconnected, that compressor would run continuously, trying to build pressure. This is a cause of most compressor failures. I'm told that later models of compressors have an overheat disconnect, but I don't think that existed for our earlier year models (I could very well be wrong here).

If you have, or have access to, a Tech 2, it has a very robust menu for troubleshooting issues with the electronic suspension control system. You can also reset the ALC (automatic level control) setting for this control system with the Tech 2, while parked on a known level surface.

Last, have you measured the ride height of all 4 corners of your truck? You can do so by measuring the distance from the center of the wheel hub to the bottom of the fender directly above the tire on all 4 corners to see what differences may exist.

Hopefully, this gives you some context for the air portion operation of the Z55 suspension. If you have any additional questions, please post them.

 

[wjburken]

So I took the z55 compressor off to inspect it due to the “service suspension” warnings I’ve had since I bought my LTZ used -
and noticed the air line to the left rear shock had been disconnected and was too taught to give it some play.
Worked that a little bit with those hose junction inside the box, and was able to get the rear left shock as well as the right one working.
When I mean working, I mean the bladder fills with air - I don’t see any change in ride height adjustment though. How does that work?
Also, inside of the box is this tiny little zip tied plastic o ring with a connection on the end that looks disconnected and I cannot find any harness that looks like ti wouldnt connect to it (enclosed photo) -anybody know what this is/does?
Also what controls the ride height and what could still be throwing a fault code if both rear shocks fill with air and the pump works?
View attachment 364865

Your vehicle likely came equipped with AutoRide and AutoLevel.

AutoRide adjusts the dampening of the shocks based on road conditions.

AutoLevel inflates/deflates the rear air shocks to keep the vehicle level.

Two separate features that are both connected to the shocks.

The previous owner may have gone cheap and replaced the front and/or rear shocks with non-AutoRide shocks and did not properly spoof the system with the necessary resistors.

Do you have a wire harness connected to your rear shocks? What about the front shocks?

On your rear shocks you should have an airline and a wire harness connection on both shocks. On your front shocks you should have a wire harness that connects to the top post of the shock under the hood.

That being said, even the proper shock could have a fault in the control module on the shock. Had a set of OEM’s go bad on my 2007.

Need to see if you can figure out what code is being thrown causing the service suspension message.