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Ask Lou P. master tech Your Own Question
Lou P. master tech
Lou P. master tech, Mercedes Technician
Category: Mercedes
Satisfied Customers: 4248
Experience:  15 years master certified 100% fix rate and have access to factory radio codes, wiring, and instructions.
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Gl550: 2008 gl 550. Car is slammed to the ground on all 4 corners.

Customer Question

2008 gl 550. Car is slammed to the ground on all 4 corners. The left rear bag is completely deflated, loose. I checked for leaks, nothing. Disconnected air line to it, crank car, no air. I capped the line, still no rise on other corners. Left it plugged. Went to front right, disconnected air line, air is pulsing out ever few seconds, high pressure, capped it, still no rise anywhere else. Pump is running
Submitted: 1 year ago.
Category: Mercedes
Expert:  Lou P. master tech replied 1 year ago.
Hello my name is ***** ***** i will do my best to help you , i strive for EXCELLENT service and nothing less. If stopping the air from entering the shocks does not help then most likely the compressor case is cracked and air is leaking right out of the air compressor , also make sure to check the front shocks as the bags can actually literally blow out , but in a scenario like yours where all four corners are down it sounds to me like the compressor is failed even though you feel air. Spray soapy water on the compressor as it is running and I bet you will see air bubbles. Hope this information helps if You need any more information please ask I am here to help. Lou. Please take a second and click the box and rate my service GOOD OR EXCELLENT SERVICE if you feel I have been helpful and please request me in the future. If you feel I have not been helpful please DO NOT RATE BAD OR POOR AND WASTE YOUR MONEY , I will opt out to see if another expert can provide more or better assistance so you're not wasting your money!!. Thanks for choosing just answer. Lou. also , if you feel i deserve one , BONUSES are GREATLY APPRECIATED ! 😉
Customer: replied 1 year ago.

That was also one of my first things to check. What about relays that controls the valve block? How do I and where are the valve block relays.

Expert:  Lou P. master tech replied 1 year ago.
the valve block is never the issue and is control module controlled. how does the pump sound when it runs?
Customer: replied 1 year ago.

Runs life it always had.

Expert:  Lou P. master tech replied 1 year ago.
If it the pump is running and nothing is rising then check the main line coming from the pump and the valve block that runs up the fender liner it may have rubbed through. If all the corners do not rise then the pressure is not getting fork the compressor to the shocks , you can pull a line off the top of the clave block and see if you have air coming out that will tell you if the valve block is working. But most often the compressor is at fault when the whole car will not lift.
Customer: replied 1 year ago.

Put it in raise mode, rear lift all the way. Front bags no air, no air going to them when line disconnected. No leaks heard

Expert:  Lou P. master tech replied 1 year ago.
Ok , and you pulled the lines off the top of the shocks to make sure ?
Customer: replied 1 year ago.

Yes. Headed to get a new relay now

Expert:  Lou P. master tech replied 1 year ago.
Relay for what ? There's only one relay and it only works the compressor. If compressor works then relay is fine. U plug the electrical connection at the valve block and make sure all the pins are not corroded and the wiring going to the valve block is not rubbed through or damaged
Customer: replied 1 year ago.

The compressor had quit running. I jumped 30 to 87 and it ran. Put in new relay. Pump comes on and immediately shuts the car off. I'm at a loss

Expert:  Lou P. master tech replied 1 year ago.
Oh wait. So it shuts the car off ?? Like turns off the car ?
Expert:  Lou P. master tech replied 1 year ago.
Ok I'm typing this assuming you meant the vehicle shuts off, if I'm wrong please let me know.
There is a issue within the front fuse and relay box. , if you remove it and take it apart you may find burn marks inside the box , that would be the reason the vehicle would shut off also very possible the issue with the compressor and air suspension. To take that fuse box loose and take the halves apart and see if the circuit board is melted and or burned. Hope this information helps
Customer: replied 1 year ago.

Yes. That's it. Now, how do I test the relay before I try again. Circuit in board is repaired. Can I test the relay with just power, ground and a test light?

Expert:  Lou P. master tech replied 1 year ago.
Power to 85 ground to 86 and it will click and allow continuity between 87/30

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