2005 Envoy Denali XL air bag suspension uneven

slaviers

Member
I have a 05 Envoy Denali XL with rear air suspension. The driver side is higher than the passenger side. I have looked at the bags and both are quite hard and inflated, just the left is inflated more than the right. Sprayed soapy water and could not see any leaks. The air compressor does not seem to run very much. It does run at start so the power up test seems to work. The light on the spare tire inflation is not blinking on start up (was told by a mechanic that it can blink error codes) and I do use it quite often to fill the tires. Where is the leveling sensor. Can't seem to find anything (sensor etc..) linking frame to axle. I do not have access to a lift, so I may be missing something. Could someone post a picture of the sensor, or a diagram of its location. Troubleshooting procedure? Are there 2 sensors or 1? Since the car is leaning toward the passenger side, either a line is blocked, or a sensor is not working. Is the level sensor in the compressor? Are the bags independent, or tied in parallel? I have worked on many semi's with air ride and adjusted the Height Control valve. Even changed air bags before. All the big rigs I have worked on are hosed in parallel.

ps. My profile shows a 03 envoy with 4.2 I6. this is a vehicle at work that I have had lots of brake problems with. The 05 denali is the Mrs's
 

RedEnvoyDenali

Well-Known Member
slaviers said:
I have a 05 Envoy Denali XL with rear air suspension. The driver side is higher than the passenger side. I have looked at the bags and both are quite hard and inflated, just the left is inflated more than the right. Sprayed soapy water and could not see any leaks. The air compressor does not seem to run very much. It does run at start so the power up test seems to work. The light on the spare tire inflation is not blinking on start up (was told by a mechanic that it can blink error codes) and I do use it quite often to fill the tires. Where is the leveling sensor. Can't seem to find anything (sensor etc..) linking frame to axle. I do not have access to a lift, so I may be missing something. Could someone post a picture of the sensor, or a diagram of its location. Troubleshooting procedure? Are there 2 sensors or 1? Since the car is leaning toward the passenger side, either a line is blocked, or a sensor is not working. Is the level sensor in the compressor? Are the bags independent, or tied in parallel? I have worked on many semi's with air ride and adjusted the Height Control valve. Even changed air bags before. All the big rigs I have worked on are hosed in parallel.

ps. My profile shows a 03 envoy with 4.2 I6. this is a vehicle at work that I have had lots of brake problems with. The 05 denali is the Mrs's
I am sorry I can't find any good pictures of the height adjusters. They are located in each rear wheel well and there is a screw and an arm that can be moved to adjust the ride height. When the sensor gets an extra load it starts the compressor and pumps up the bags and when it detects they are too high it releases some air to lower the bags.

When I put a load (boat and trailer)the compressor will start to raise the rear end, I never hear it re-adjust to lower the bags.

You may have to pull the rear wheels to locate them.

here is a link to Rockauto showing the adjusters, you will notice there is a left and right so I think there are two. Good Luck

RockAuto Parts Catalog


 

The_Roadie

Founding Member
Administrator
There is a sensor for each side, and if you slightly loosen their mounting screws, you can rotate each one a tiny bit for an adjustment. You have to ride around for a while before it settles into the new position and you can measure your wheel well height with a tape measure. If a sensor was dead or had bad wiring, the error light would indeed flash at you.

View attachment 24010
 

Attachments

BRomanJr

Well-Known Member
slaviers said:
I have a 05 Envoy Denali XL with rear air suspension. The driver side is higher than the passenger side. I have looked at the bags and both are quite hard and inflated, just the left is inflated more than the right. Sprayed soapy water and could not see any leaks. The air compressor does not seem to run very much. It does run at start so the power up test seems to work. The light on the spare tire inflation is not blinking on start up (was told by a mechanic that it can blink error codes) and I do use it quite often to fill the tires. Where is the leveling sensor. Can't seem to find anything (sensor etc..) linking frame to axle. I do not have access to a lift, so I may be missing something. Could someone post a picture of the sensor, or a diagram of its location. Troubleshooting procedure? Are there 2 sensors or 1? Since the car is leaning toward the passenger side, either a line is blocked, or a sensor is not working. Is the level sensor in the compressor? Are the bags independent, or tied in parallel? I have worked on many semi's with air ride and adjusted the Height Control valve. Even changed air bags before. All the big rigs I have worked on are hosed in parallel.

ps. My profile shows a 03 envoy with 4.2 I6. this is a vehicle at work that I have had lots of brake problems with. The 05 denali is the Mrs's
There are 2 sensors as noted, and can be adjusted a number of ways.

If the vehicle is not level side to side, the documented GM procedure should be used, it requires jacking but a lift and a jack work best.

If this happened without any work being done around the sensors then possibly one of the sensors is failing and giving bad/innacurate readings.
 

jrSS

Well-Known Member
Just so u know......... driver side slide the bracket back (right) to lower. Forward (left) to raise

Passenger side is the opposite.......slide bracket forward(right) to lower and left to raise. Go in SMALL incriments. Good luck.

Keep the truck in the "run" position so the sensors have power
Mark the bolts w/ some white out(b4 u mess w/ sensors) incase u get them outta wack so u have a place to return.
 

jrSS

Well-Known Member
Also...I wish I could put a link up but there is a youtube video of NorcalSS lowering a tbSS with bags.
 
OP
OP
S

slaviers

Member
there was a +1-1/2" difference between LH and RH fender heights. Took LH rear tire off, loosened bolts (10mm socket) and slid the sensor rearward and CCW. Put tire back on and drove the vehicle for a couple of miles and remeasured the heights. Both are now 32-1/2" +/- 1/8".View attachment 24023:thumbsup::biggrin: Also, forgot to mention to be sure and check that the tire pressure is correct (35 psi rear and 30 psi front) per the driver door jam placard before taking the measurements. I just used a SWAG to judge how far to move the sensor.
 

Attachments

CharlestonUSC

New Member
My envoy 2006 slt is not keeping a normal height either. Both sides are equally bottomed out. The compressor works and doesn't give any light flash faults. It is an intermittent issue as sometimes it works fine and other times it doesn't raise the vehicle to the correct height. If it was one sensor not working wouldn't one side still raise? And it isn't a leak bc it isn't a consistent problem.
 

BRomanJr

Well-Known Member
CharlestonUSC said:
My envoy 2006 slt is not keeping a normal height either. Both sides are equally bottomed out. The compressor works and doesn't give any light flash faults. It is an intermittent issue as sometimes it works fine and other times it doesn't raise the vehicle to the correct height. If it was one sensor not working wouldn't one side still raise? And it isn't a leak bc it isn't a consistent problem.
IMHO,

Normal operations:
If the compressor runs for a few seconds shortly after the Truck is started, that is normal.
If it runs because you added weight, it should only be for a few seconds to a minute depending on the weight added.

Not Normal:
If the compressor runs but sometimes lifts and sometimes not, it is probably the serviceable check valve on the compressor. The is a strictly mechanical one-way check valve for intake air to the compressor.
When it leaks, the compressor can't build up pressure to raise the vehicle. GM has a TSB on it.

I agree if it was a sensor, your light at the inflation port would be flashing a code.
 

Wooluf1952

Well-Known Member
CharlestonUSC said:
My envoy 2006 slt is not keeping a normal height either. Both sides are equally bottomed out. The compressor works and doesn't give any light flash faults. It is an intermittent issue as sometimes it works fine and other times it doesn't raise the vehicle to the correct height. If it was one sensor not working wouldn't one side still raise? And it isn't a leak bc it isn't a consistent problem.
:tiphat: :tiphat: Welcome :tiphat:


In case you haven't heard:
http://gmtnation.com/forums/topic/218-welcome-to-gmtnationcom-heres-the-story/


There is a check valve rebuilding kit available from the dealer (part #15183676, about $35) or possibly Rockauto. IIRC, it's for the check valve between the compressor and the air distribution block.
 

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