Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum banner

1 - 19 of 19 Posts

·
Registered
2002 gmc envoy_slt
Joined
·
53 Posts
Discussion Starter #1
I have been searching and find lots of issues with these air suspensions but none of them are like my issue.

Just today I realized I don't hear the air suspension when I turn the the Envoy on. The rear looks a little low, not too low though.

I think I checked the right fuse (ECAS under hood). But my issue is it doesn;t seem like it is working at all. I read a lot of issues about air leaking.

Any quick suggestions?
 

·
Banned
2004 gmc
Joined
·
26,181 Posts
Does it run when you turn on the manual switch and connect the hose like you're going to inflate a beach ball with the system? Do you have a meter and want to trace electrical connections?
 

·
Registered
2002 gmc envoy_slt
Joined
·
53 Posts
Discussion Starter #3
The inflation system does not work at all, the light never turns on.

I do not have a meter, but I can pick one up if I knew what to do with it.
 

·
Banned
2004 gmc
Joined
·
26,181 Posts
You might need a friend or a mechanic with some electrical troubleshooting experience and access to the schematics. No other quick suggestions come to mind when you have either a dead compressor (big $$) or a wiring harness issue.
 

·
Registered
2003 gmc envoy_slt_xl
Joined
·
77 Posts
Compressor.

I have been searching and find lots of issues with these air suspensions but none of them are like my issue.

Just today I realized I don't hear the air suspension when I turn the the Envoy on. The rear looks a little low, not too low though.

I think I checked the right fuse (ECAS under hood). But my issue is it doesn;t seem like it is working at all. I read a lot of issues about air leaking.

Any quick suggestions?
You can look under the back of the car, there are some rubber bump stops. Is the chassis bottomed, laying on the bump stops, or is it above that?
If it's not laying all the way down you have air in your air springs.

The compressor is the only way it could have gotten there. So either the compressor isn't working however there are NO LEAKS at all and there is some amount of air trapped there, which seems hard to believe, or the compressor is working at some point.

By the inflator switch there is a valve stem. Push on the shrader valve and air should come out if there is pressure in the system. If you push the shrader valve and NO air comes out then your rear suspension must be bottomed against the bump stops.

But you say it's not too low. That sounds odd.

The height of the rear is called D Height.

I posted the troubleshooting info for this problem here.
http://forums.trailvoy.com/showthread.php?t=72264
Read in section 1 about how to measure the D Height. Section 2 contains troubleshooting for the compressor and the height sensors.

It's either bottomed, or not and air is somehow staying in the system, or it's working.
 

·
Registered
2002 gmc envoy_slt
Joined
·
53 Posts
Discussion Starter #6
Okay, it would appear that it has bottomed out. The back is super bouncy. I am not in front of it right now to see the bump stops but I am pretty sure it has bottomed out.

I read the other thread and this seems way too difficult for me to try to diagnose and I don't know anyone that would be able to help me.

So online the compressor is around $430. If I was to bring it in what would I be looking at for total cost? Is the dealer the best place to go? Anyone have experience with dealer letting them bring their own parts in and the dealer does the labor?

I just want to be able to not get ripped off and I don't think I can do this myself.
 

·
Registered
2002 gmc envoy_slt
Joined
·
53 Posts
Discussion Starter #7
I would say it's probably not a leak since the wife said it hasn't worked for 30+ days now. the only thing that happened is I put 200lbs in the back and thats when I started to notice it.
 

·
Registered
2003 gmc envoy_slt_xl
Joined
·
77 Posts
If it's bottomed out and has no air in the air springs the ride will be very bouncy and uncomfortable.

I don't think there is any way you wouldn't notice it.

That car is supposed to be high in the back, if it's level front to back that's not right.

Mine was flat, no air at all after being parked and if I didn't wait for the compressor to pump it up for a few seconds, about 30 or 40, it was really rough. Mine did hold air while driving but the compressor was likely running too much. So that had to be fixed.

When you turn on the key, if the suspension needs air in the back the compressor will start. It's in the back, you can hear it plainly, especially if the engine isn't running.

Is the ECAS compressor running or not? You can test this by pushing in the shrader valve in the inflator, and it should definitely go on if you let the air out. You can see the car raising.

If the compressor isn't going on fix that first. If your compressor is unplugged, or has a blown fuse or something, buying a new one won't help.

If the compressor is going on but isn't raising the back of the car you have a leak.

You have to find out which it is. Throwing money at it and buying new parts is not the way, unless they are very cheap parts like the check valve I put in. I may not have needed it but for $28, what the heck.
 

·
Registered
2002 gmc envoy_slt
Joined
·
53 Posts
Discussion Starter #9
Okay so are you saying if the compressor never turns on it might not be the compressor that is bad?

1. ECAS Fuse under hood is good
2. Inflator does not work at all (Light never turns on)
3. Back is bottomed out
4. Never hear the compressor run anymore

I have no idea how to check if it is unplugged and not sure how that would happen. Is there any other fuse to check?
 

·
Registered
2003 gmc envoy_slt_xl
Joined
·
77 Posts
Okay so are you saying if the compressor never turns on it might not be the compressor that is bad?

1. ECAS Fuse under hood is good
2. Inflator does not work at all (Light never turns on)
3. Back is bottomed out
4. Never hear the compressor run anymore

I have no idea how to check if it is unplugged and not sure how that would happen. Is there any other fuse to check?
So you know the compressor used to run?

BTW, when you click the inflator switch, the bottom part of the switch is what pushes in and makes it go on. Not the top. It's a momentary type switch, you push once for one once for off.

There are several plugs that connect to the compressor, there are three technical bulletins I posted in that other thread. There is troubleshooting info in pt2, I think. Connect a wire from here to there, and the compressor starts.

Since you can't replace that compressor without unscrewing the two bolts and lowering it down you might as well just unscrew the two bolts and check it out. The problem may be obvious at that point.
 

·
Registered
2002 gmc envoy_slt
Joined
·
53 Posts
Discussion Starter #11
I have been reading over the guides, some of the electronic stuff looks like I can handle. I found the compressor under the vehicle and it does seem easy to get to.

When trying to find the DTC codes, I am not understanding how to do it? The LED on the inflator switch is always off, I am unable to turn it on at all.
 

·
Registered
2003 gmc envoy_slt_xl
Joined
·
77 Posts
Okay so are you saying if the compressor never turns on it might not be the compressor that is bad?

1. ECAS Fuse under hood is good
2. Inflator does not work at all (Light never turns on)
3. Back is bottomed out
4. Never hear the compressor run anymore

I have no idea how to check if it is unplugged and not sure how that would happen. Is there any other fuse to check?
There is troubleshoting info on the documents I posted, I think in part 2. You need to try that. One test was to connect a wire from here to there and the compressor has to start.

What if a plug is unplugged? You would be sorry if you bought a new one and took the old one out to install it and find it's just not plugged in or has some other obvious problem.
 

·
Registered
2003 gmc envoy_slt_xl
Joined
·
77 Posts
I have been reading over the guides, some of the electronic stuff looks like I can handle. I found the compressor under the vehicle and it does seem easy to get to.

When trying to find the DTC codes, I am not understanding how to do it? The LED on the inflator switch is always off, I am unable to turn it on at all.
It looks like there is no electricity coming out of the wire at the back of the car. So the compressor and light are off.
 

·
Registered
2002 gmc envoy_slt
Joined
·
53 Posts
Discussion Starter #14
It looks like there is no electricity coming out of the wire at the back of the car. So the compressor and light are off.
Right so by hooking a test lamp to something would it tell me? Or is this issue with no power something totally different than what I am testing for. I just reached under the vehicle tonight, everything is plugged in. The vehicle was moved to Vegas 2 years ago so it has been in extreme heat for a couple summers already.

The no power thing made me think Fuse immediately but the #1 ECAS fuse is good.
 

·
Banned
2003 gmc envoy_slt
Joined
·
7,190 Posts
Did you actually test the fuse? Or just look at it? Some times the fuse can look good, but be bad where it doesn't show. Or the fuse socket can be loose. :m2:
 

·
Registered
2002 gmc envoy_slt
Joined
·
53 Posts
Discussion Starter #16 (Edited)
Did you actually test the fuse? Or just look at it? Some times the fuse can look good, but be bad where it doesn't show. Or the fuse socket can be loose. :m2:
Fuse is good for sure, now I gotta get a test lamp and try to rest of the stuff. Although I am worried I won't find the issue since it seems to be a power issue.
 

·
Registered
2003 gmc envoy_slt_xl
Joined
·
77 Posts
Fuse is good for sure, now I gotta get a test lamp and try to rest of the stuff. Although I am worried I won't find the issue since it seems to be a power issue.
If you are really not well versed in this type of automotive electrical troubleshooting maybe you should get some help. Maybe a friend who is good at such stuff?

There are wiring diagrams that are downloadable from the resources menu above.

I have helped friends with stuff like this. It's not that complicated with experience, and I am no mechanic. But sometimes a fresh pair of eyes can see something. Hopefully it will be something simple. No power at all, that might be straightforward. DOH!

Good luck!
 

·
Registered
2006 gmc envoy_denali_xl
Joined
·
9 Posts
Riding Low...

...Is the ECAS compressor running or not? You can test this by pushing in the shrader valve in the inflator, and it should definitely go on if you let the air out. You can see the car raising.

If the compressor isn't going on fix that first. If your compressor is unplugged, or has a blown fuse or something, buying a new one won't help...
Hi so, I know this is an old thread, but it most closely resembles my situation. Riding low, compressor won't come on and doesn't run at first like it always did for diagnostics. Poked around yesterday a bit, it will run in inflator mode. I'm at the office now but will check the #48 fuse this afternoon. Downloaded and printed all the Diag files by Steevo (thx!).

Mainly just want to ask if anyone ever tried to pump up the bags using the schrader fitting at the rear? That would be a great backup feature for when the compressor quits running, to keep the frame off the bump stops.
 

·
Registered
2006 gmc envoy_denali_xl
Joined
·
9 Posts
Hi so, I know this is an old thread, but it most closely resembles my situation. Riding low, compressor won't come on and doesn't run at first like it always did for diagnostics. Poked around yesterday a bit, it will run in inflator mode. I'm at the office now but will check the #48 fuse this afternoon. Downloaded and printed all the Diag files by Steevo (thx!).

Mainly just want to ask if anyone ever tried to pump up the bags using the schrader fitting at the rear? That would be a great backup feature for when the compressor quits running, to keep the frame off the bump stops.
So, I tried pumping up the bags at the schrader fitting. No joy. There must be a check valve somewhere in the system that will allow you to depressure the bags but no fill them. Bummer.

I did find the left height sensor was broken; may have happened when I lifted the rear wheels of the ground to re-set height. Sucks, that's a bad design feature... :duh: I read in another thread about someone accidentally doing the same thing. I'll order it from Rockauto (why is the left side $105 and the right side $40???). I'll try to set both of them so they won't stretch with back wheels off the ground. If possible...

Then maybe the compressor will start working again after I replace the left sensor. I'm thinking with the left sensor not functioning, the readings from both sensors are so far apart that the compressor went into shutdown mode. No DTC showing btw.
 
1 - 19 of 19 Posts
Top