shred101

Hi guys,

I have a 2007 GL450 that is experiencing Airmatic issues. It keeps kicking up code 5507 (suspension strut is implausible) after trying to raise the suspension with the airmatic button on the console. It does raise the suspension some (all four height sensors showing change in height), but after a while, it kicks on the airmatic malfunction warning. When trying to lower the suspension, it lowers the suspension some, but continues to show that it is still lowering via the airmatic message, without actually lowering after a short time. After hooking up my scanner and viewing the airmatic pressure sensor (Y36b1), I noticed the readings are extremely sporadic (see attached video). Is this caused by a faulty compressor or possibly the valve block? Hoping it's not the compressor, as I have had to replace this twice already in the past. I also replaced the valve block in the past as well.

Max Blast

Check that the level sensor of the strut you're getting the error on isn't overtraveled.

BlackML550

Compressors only die due to being overworked because of a leak. You didn't say if you had replaced any airbags (the usual culprit) at all, but you've been through 3 compressors? The malfunction warning is the compressor overheating. Have you done a soapy water test on all components?

shred101

Replaced front struts about a year ago. All the struts never sag, even after sitting for several days without the car being started. Thinking I'm just having terrible luck with the compressors. And the compressor isn't overheating.

shred101

I checked them, but all level sensors seem to be in order.

BlackML550

Did you change the relay as well as the compressors? The factory relay was known to allow the compressor to overrun.

shred101

Yeah, changed the relays both times when I changed the compressors before. Thinking the issue could be the valve block not allowing enough air through. Also, the pressure from the pump (showing on the scanner) is completely bonkers, goes from 1.5 bar to over 30 bar. back and forth. You can see it in the video I attached to the original post.

BlackML550

From here it looks like a process of elimination. Work out what works to work out what doesn't. Seems like you're looking in the right spot. Be wary of the airbags. Soapy water test showed me that unless you have the bags fully inflated to their highest level, AND with the car on its own weight, not jacked up, the leakes can hide. You need the weight of the car to adequately pressurise the system to find the leak. Other than the valve block, the only other thing I could suggest is that the electrics are somehow forcing the compressor on when it shouldn't be on. Might have to test all the ride height sensors one by one? Patience is the key when testing

eric_in_sd

Are you using an AMK branded compressor? Chinesium compressors fail quickly. Varying air pressure at the sensor could result from that.

Your varying air pressure could also be due to a Chinesium valve block, with a garbage pressure sensor and garbage valves.

When it comes to the pump and valve block only get AMK; the good valve blocks all cost in the mid $250 range. I put in a $50 Ebay valve block and it never worked at all.

BlackML550

Agree with this 100%. AMK is the onky aftermarket brand to get.