2005 GMC Envoy Denali ALC Issue

[RobHilton]

Good Day Y'All, new to the forum for the reason listed in the title. Looking to get some advice from all you experts out there. This is my wife's vehicle and it has 124,000+ miles. I changed the air bags two years ago when one developed a leak. System was working just fine until we got ready for a road trip and I noticed the rear end sagging. Usually when I start the vehicle you can hear the compressor come on and run until it is level. Not the case now, on the schematic I got on line I checked the "4WD fuse #48" and it is good, checked the "ECAS Fuse #1" and is good. Oh, I did check the "Air Suspension Inflation Switch Function" and the light illuminate and the compressor turns on and the compressor runs with plenty of air pressure. What I have not tested are the two air suspension level sensor. Also, in my research I have not been able verify if there is a relay somewhere in the system that would be switching on the main power. Given there is a 30 amp fuse I would have thought there would be a relay? If there is a relay were would it be locater? Thanks in advance for any help you might provide. Rob

 

[Machoman]

Good Day Y'All, new to the forum for the reason listed in the title. Looking to get some advice from all you experts out there. This is my wife's vehicle and it has 124,000+ miles. I changed the air bags two years ago when one developed a leak. System was working just fine until we got ready for a road trip and I noticed the rear end sagging. Usually when I start the vehicle you can hear the compressor come on and run until it is level. Not the case now, on the schematic I got on line I checked the "4WD fuse #48" and it is good, checked the "ECAS Fuse #1" and is good. Oh, I did check the "Air Suspension Inflation Switch Function" and the light illuminate and the compressor turns on and the compressor runs with plenty of air pressure. What I have not tested are the two air suspension level sensor. Also, in my research I have not been able verify if there is a relay somewhere in the system that would be switching on the main power. Given there is a 30 amp fuse I would have thought there would be a relay? If there is a relay were would it be locater? Thanks in advance for any help you might provide. Rob

I do the redneck check on my level sensor. Start the car up and stand on the rear bumper. The compressor should kick in.

 

[Mooseman]

This is a really failure prone system and we usually recommend that it be replaced with springs. I.know.you lose rride quality but the compressor is no longer available or very expensive to replace.

 

[RobHilton]

Yes, replacing the system with coilovers has been on my mind. But, as you mentioned the current system gives a nice ride and when I tow trailer, self leveling is a great feature. Rob

 

[TJBaker57]

I am not familiar with the air suspension system as I do not have one. However, after a quick look at yhe schematic it appears there is no relay.