BenzWorld Junior Member
Date registered: Jul 2018
Vehicle: 2007 GL450
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
2007 GL450 airmatic troubleshooting assistance
Hi all, I have a 2007 GL450 with an airmatic issue that I could use some troubleshooting assistance with. Sorry for the long post but I prefer to give all the information I have and it helps me organize my thoughts lol.
Iíve been reading through the forums looking for things to check and am still not positive what the issue is. My nearest dealer is 150 miles away so driving there is not a good option, so I purchased an Autel meter to be able to read and reset the codes. The meter suggests the pressure release valve is faulty, but I know that doesnít necessarily mean that is the case. So in troubleshooting, I have:
1. Checked all 3 fuses. All are good.
2. Replaced the relay. Cheap possible fix, no effect.
3. Checked power to the compressor, didnít seem to have any, hence the relay replacement. I am not certain I measured the voltage correctly.
4. Checked for corrosion/broken wires going to the compressor/valve block, all appeared to be ok, but there appears to be heat damage to one side of the power plug. However, it does appear to still have a connection, albeit maybe not the most pristine.
5. Reset all codes via scanner, drove the vehicle for a day, then read the current codes. Only one for airmatic, as mentioned above.
6. Disassembled compressor/valve block assembly, all looks in order, more on this in a minute.
7. Checked for leaks, found none.
Now for the history. Car ran fine until one day the malfunction light cam on. It rode ok for a week or so then noticed it was riding really rough like it didnít have air or even springs. I jacked the car up to perform an inspection and after that the car started riding like it was ONLY on springs with no dampening at all. It felt like I was riding in one of those lowriders with the hydraulics active! Nothing I tried would get the suspension to air up, but somehow during my troubleshooting I noticed it was airing up and it leveled out to the proper level. I figured I must have done something that fixed it (without knowing what it was of course) and took it for a test drive. It malfunctioned again on the next drive, but it maintained pressure for two weeks, until I got brave and jacked it up again to perform brake maintenance. While the front wheel was up, I saw it rising (I noticed this the first time it bottomed out too) and now I am back to the lowrider again after putting it back on the ground. I have since been focusing on the compressor and valve block.
So one thing I noticed was any time I disconnected the air line between the compressor and the valve block, it was always pressurized. I also noticed that I have never been able to see/hear/feel the compressor run, and that has always sat in the back of my mind when I didnít seem to have power to the compressor. I disconnected the air line and left it off while I started the vehicle so that I could see if it ever put out any air. I discovered that it does not do so when it is supposed to, or when it is trying according to the dash, BUT when starting the vehicle, the compressor does it fact turn on and compress for 1-2 seconds.
So Iím having trouble deciding where to go from here. The compressor appears to have power, but doesnít seem to be turning on when it needs to. The scanner suggests the valve block, but when the compressor doesnít even seem to want to kick on when itís supposed to, I am reluctant to think that is it. Now I am starting to suspect the computer might not be sending the signal, but would think the scanner would catch that.
Ok thatís where Iím at. Thanks for reading and thanks in advance for any advice.