Auto leveling

[kepler47]

I have a 2013 qx56

The compressor works and inflates the suspension which levels the truck. My concern is that it seem like it deflates after the truck is turned off. Is this normal ? Or does it suppose to stay level.

 

[marctronixx]

Hi.
No its not normal. The car stays level always. It will inflate when needed and release air when the rear is too high. There is a auto level sensor back under there by the compressor that governs this. Its a mechanical arm and can be adjusted if needed. In your case it sounds like its fine but is perhaps leaking. This has happened to others over the years.

 

[primov8]

I posted this over at clubarmada.com a couple months ago.

The auto-leveling rear compressor has an internal exhaust valve solenoid. The purpose of that valve is to vent air out when additional height isn’t needed; info relayed from the height adjustment arm to the auto-level ccu.

Unfortunately, that internal exhaust valve can corrode, which will lead to the rear suspension sagging because the valve is stuck open/leaking and not inflating the bags when needed.

It sounds like you’ve already ruled out the air shocks and lines not being the issues, therefore replacing the compressor should fix the rear suspension woes.

A friend of mine went through the same exact situation with his 08 QX56. He replaced the air shocks, height sensor and his compressor would turn on, but the rear would eventually start sagging once he drove off. We finally had the chance to meet up and I used my diagnostic tool to check out his auto-leveling system. It immediately showed a DTC for the exhaust valve solenoid. Also, when I turned on the compressor, the motor itself sounded very weak and took some time to inflate the rear shocks.

He installed a new compressor just last week and he immediately noticed the huge difference. Not only did the new compressor sound healthier, it inflated the rear shocks much faster.

If you happen to know a shop that has a diagnostic tool that does more than just read engine DTCs, have them scan the auto-leveling system to look for the exhaust valve solenoid DTC.