ECAS operation questions


Original poster
Dec 5, 2011
Central Pennsylvania
Hello all. I'm hoping to get some feedback on the ECAS in my '02 Bravada. My wife and I have identical '02 Bravadas (same trim, color, etc). We both have I6, etc...

When her ECAS engages the rear lifts at a noticeable pace, when it reaches height, the compressor shuts off with a "pachissss" sound, sort of like a tractor trailer's breaks. It then won't engage unless it sits for overnight or the load increases.

When my ECAS engages (which it does every time I get in it, and several times for the first few miles) I have a hard time noticing the rise in height. When the compressor shuts off, there is no sound - it just stops.

With 108k miles on it, I'm sure something in my ECAS system needs work, but I'm not sure what. I want to get under it and check for leaks in the springs and lines but haven't yet.

Is the sound hers makes "normal"? Should I be concentrating on the pump, the lines, the springs or something else?


Lifetime VIP Donor
Nov 19, 2011
Portland, OR
I don't have the system, and I'm sure someone who does will chime in, but in my years of reading threads about ECAS problems, nobody has ever mentioned a noise when the compressor stops. There is a vent valve to let pressure out, though, so that might be the source. But I'd be asking why it needs to pump up every morning. Unless there's a leaky bag, line, or valve, it should retain its height overnight. You may have problems in both vehicles.

And it's difficult to localize leaks without a lot of soapy water spray.

You can swap compressor assemblies with one from Ebay or the aftermarket Arnott unit. Or junk the system altogether and install coil springs. If adjustability for towing is very important to have on one truck or the other, just slap in Airlift1000 bags inside the coil springs and inflate them by hand or by a manual compressor (also sold by Airlift).



Nov 20, 2011
Milwaukee, Wisconsin
Your compressor should run for a short time every time you start the truck. It's a test and usually doesn't affect the ride height.
I've never heard the air escaping sound from my '03.

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