ECASS Electronically Controlled Air Suspension System - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum



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Go Back   Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum > 2002 - 2009 TrailBlazer/Envoy Tech > 02-09 Brakes, Suspension, Wheels and Tires > Suspension

Suspension Suspension

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  #1  
Old 03-18-2008, 09:30 AM
bobbrown6507 bobbrown6507 is offline
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ECASS Electronically Controlled Air Suspension System

Can anyone assist me with any type of diagram or schematic for the ECASS "Electronically Controlled Air Suspension System." The air compresser on my 04 XUV strangely ran without me (my wife) knowing until it killed the battery. (Then my IAC went haywire until the ECM could relearn it's status/condition under load --- another story) I pulled the fuse on the Air Susp, system until I had time to troubleshoot. I put the fuse back in and now the air compresser barely works (lucky my suspension air bags do not leak). I'd be surprised if this costly-looking air compresser is bad @ 60k miles. I planned to pull it out and troubleshoot it on the bench, but after cutting the spare tire out to access it(spare tire winch siezed - vehicle seems like a lemon so far) I saw how complicated this thing really is (2 different harness connectors and several air lines, 1 big and a few small). I'm positive I have no air leak. I assume it's getting it's call for air from a solenoid or the ECM but not sure. Maybe the compressor is shot. I also have access to a Tech 2 but didn't know if that would help. I need any help troubleshooting this. Thanks, Rob
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  #2  
Old 03-18-2008, 11:41 AM
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i know Ive seen pics of guys on here replacing a failed pump with some they had laying around (not OEM parts). they somehow got theirs to work.
Ive also seen OEM pumps on ebay.
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Old 03-18-2008, 07:39 PM
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the compressor is kicked on by two height sensors bolted to the frame behind each wheel. The bolts on those may have come loose and the sensors are telling the compressor to kick on. They could be moving randomly and changing ride height settings constantly

Did you notice the rear higher than normal at all? If not then their is possibly a leak somewhere so the compressor is just keeping the PSI where it should be
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Old 03-19-2008, 08:03 AM
bobbrown6507 bobbrown6507 is offline
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Thanks for the responses. I'm sure it is not leaking. My ride height has not changed at all since the compressor has been disconnected. I do appreciate your enlightenment on the location of those sensors. I'll definately inspect them. The mystery of it all is: Why was it running so much before it died? That's why I'm looking to see where all these wires come from that go into this compressor. I see some brave folks on this sight have simply elliminated it completely, tied the 3 lines together with a Tee and now adjust their ride height from the port in the cargo area. I like that. I may do that also while I look for another compressor (I'd rather seek an OEM but not if they haven't enhanced them). Everywhere I look I read this systems suffers tremendously. This is definately a weak spot in GM engineering of these vehicles. I keep my cars for many years and I'm sure I haven't seen the last of my trouble with this airbag suspension system. Any further help with these schematics or insight is greatly appreciated. I would love to purchase the OEM dealership repair manual but find it difficult to locate them. I guess I'll try Haynes or Chiltons. Thanks, Rob
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Old 03-19-2008, 12:55 PM
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i remember seeing a pic on here on the location of those switches.
If I remember correctly someone moved them to change the ride height.
I too was surprissed at the location of these.
theyre literally right there in the wheel well
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Old 03-19-2008, 10:20 PM
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Quote:
Originally Posted by rbarrios View Post
i remember seeing a pic on here on the location of those switches.
If I remember correctly someone moved them to change the ride height.
I too was surprissed at the location of these.
theyre literally right there in the wheel well
Yup, the SS guys and some Envoy guys are adjusting them to lower the truck. They are placed at the wheels for the most accurate reading of how much the ride height has changed.
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Old 03-24-2008, 09:18 AM
bobbrown6507 bobbrown6507 is offline
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Thanks for the help.
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Old 03-24-2008, 08:05 PM
n0kfb n0kfb is offline
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Here is a diagram from AlldataDIY.com for an '05 Envoy air suspension.

-- Dan Meyer
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Old 03-24-2008, 08:08 PM
n0kfb n0kfb is offline
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How often does your compressor run? Since the day I bought my '06 Envoy, I've complained to the dealer that the compressor runs too often. All they ever do is test the system, and tell me everything is OK. I called GM to try to contact someone who designed the system, and all GM would do is refer me to the dealer. As you might guess, this ticked me off.

On my own, I've determined that the ECAS is likely made by Wabco, and I fetched their brochure from their web site some time ago. I'd attach the .PDF, but I am getting a warning that the file is too large.

-- Dan Meyer
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Old 03-25-2008, 09:32 AM
bobbrown6507 bobbrown6507 is offline
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Dan,

I am most greatful for your contribution. Maybe you could try to send me that file to rsmithfj40@comcast.net

My compressor (when at it's worst) was turning on about every 1-2 minutes and would run for approx. 20-30 seconds with the vehicle off (drained the battery overnight). When it seemed 'more normal' it would run only when the vehicle was running (usually after start-up). I just bought this Envoy in Oct. 07 (e-bay auction - used-60k miles) and heard that compressor immediately. I measured ride height daily and it never changed and still no change with the fuse pulled. I guess I'm lucky I haven't sprung a leak. Now the compressor is completely dead when powered. I'm waiting for the day I come out and it is sitting on the axle!!! I search e-bay very often and have never seen an OEM replacement. I truly believe that this system will be more troublesome as it ages. I bet these OEM replacements will be a nightmare to find and afford. I'm planning to pull the compressor out see whats what. Maybe it can be rebuilt. I haven't put the Tech 2 on it yet. I'm not sure if the Tech 2 will communicate with the compressor.

Thanks again,
Rob Smith
586-634-4300cell
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