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Rear Ride height sensor on Envoy Denali

18K views 17 replies 7 participants last post by  lylesg 
#1 ·
My 2006 Envoy seems to go down in the rear at time over night. Not always but more times than not. Does anyone know where I can get a ride height sensor and can I do it myself?

Thanks from NY.
 
#2 ·
If it pumps back up in the morning to the expected height, your problem is not a sensor (which are off anyway overnight). It's bag, valve, or line leakage. Common problem with aging vehicles. Discussed plenty as well......

I would just hate myself if I let you buy a sensor and slap it in. Even on 4/1. :crackup:
 
#3 · (Edited)
The sensors (1 on each side) almost never fail. If the truck goes down while it is parked, it is not a sensor problem because the system is off.

Only an air leak can cause the rear to drop when parked.

Most reports are for bad air bags (original and aftermarket parts available)

Air Compressors also fail and occasionally air lines and fittings fail.

Soapy water in a spray bottle may reveal a leak, support the truck while you are under there, The system will stay pressurized even when jacked up, while you check for leaks.

Edit:I was too slow again.
 
#4 ·
roadie and bromanjr thank you for the replies. I thought it was the air bags also but the problem is that the rear doesn't always drop. At times it will drop within an hour other times never or several hours like over night. If no leak revealed with soapy water how likely are the chances of it being a sensor issue?

Regards
 
#5 ·
... how likely are the chances of it being a sensor issue?...
Absolutely zero. The system powers off with the ignition. Sensors are not being looked at with the system off.

The air bags retain their pressure while the ignition is off only if the valves in the compressor assembly close fully. So if they have a problem, like dirt in the seat, then the pressure will leak out. Same with leaky hoses or bags. So if you have an intermittent problem that isn't revealed by soapy water spray, it's more likely to be the compressor valves than the bags.

Removing the bags for a good inspection isn't out of the question. But I'd be looking at rebuilding the compressor or if that's not your thing, buying one from Ebay or the Arnott replacement.
 
#6 ·
Mine sits noticeably lower on the passenger side. (rear) Thought it was me..:weird: Until I measured. The rear end sits 1.5 inches lower on the passenger side. This, after about 10 minutes of sitting. I am also getting a lot of road noise now. By that, I mean it sounds like I have swampers on the truck. Tires are 8 months old, and have been fine. Can the air leak cause any rubbing issues? Hence, the moan I hear when rolling?

Thx

Chris
 
#8 ·
Unlikely a sensor adjustment if you haven't moved them.

Usually when only one side leaks down side or rides lower, it it something failing on that side. This could be the bag, the line or the Solenoid/Check valve in the compressor.

There is a solenoid/check valve for each side and they can operate at the same time or independently if needed.
 
#9 ·
The sensors WERE moved, to try to reduce the "Jacked up" look to something resembling normal. Following the first adjustment (by the dealership) I noticed that the pass side was down in the driveway and then down while driving. Do the sensors only operate the bag on their respective side?
 
#11 ·
...the first adjustment (by the dealership) ...
That's usually the beginning of a story that ends up poorly... :cry: You should have held their feet to the fire until they did the job you paid them to do. But of course the annoyance and inconvenience factor of leaving the vehicle somewhere for a day or more usually gets owners to not complain. Sorry to hear. But it's easy to move yourself - just do tiny changes and drive around for a while before getting out your tape measure to confirm the change. Keep a log so you'll know how much to move them to home in on perfection.
 
#10 · (Edited)
Yes, each side can independently signal too high (opens solenoid with compressor off) or too low (runs compressor then opens solenoid to raise). Usually they happen at the same time when you add or remove weight after key on or engine start.

I've heard of the system getting confused during adjustments, not sure what the fix has been. Try removing the fuse, or maybe jacking vehicle up to get them both to register high, then let down and see if the system picks up correct signals.

Finally, if they have been messed with and are way out of adjustment, put them both back to a central adjustment.

There is a procedure in the service manual to set "ride height". That process can be used with a modified dimension to get other than stock ride height. If one bolt has been removed, there is a larger adjustment range, but also a larger mis-adjustment possibility.
 
#12 ·
Will do! I have found that I don't have to remove the wheel to get to the sensor adjustment bolts, just jack the frame to get the tire out of the way. I will center both sensors and begin from there. When the bolts are loosened, there is vertical play as well as rotational play, so first I'll set them in the center of the rotational plane, then make sure that both are at the top of the vertical plane.

Whew.. sounds like a head scratching evening...
 
#15 ·
Well... I got the 'Voy up to do the adjustments and saw that the pass side bag WASN'T EVEN ATTACHED to the rear axle... the bag was totally deflated and just hanging there, wobblikg around. When I put the jack down, it set itself back in the right place... but won't inflate...

Screw it.. I'm going to springs...
 
#16 ·
NOW THE QUESTION FOR THE FORUM IS...

I have ordered the Strutmaster springs... I have brand new KYB shocks on the car all around, so I'm not interested in changing the rear shocks. I ordered the "Springs Only" kit. So far, so good.

I read in another thread that "Isolators" were recommended for the top of the springs. I found the part number and got them on the way, too.

But... Nowhere on the Strutmaster site does it say anything about "Isolators" or "insulators"... Are these needed for noise reduction? or ride quality??
 
#18 ·
Air ride sensor linkage

On my Buick Rainier, the plastic linkage rods on both sides deteriorated terribly and one broke in half so I made a replacement one out of a piece of nylon which brought the vehicle back into factory spec of 1/2" side to side. For the other side linkage (passenger) I made a replacement linkage with an adjusting nut. I can reach behind the tire and fine tune the nut which brings equal distance off the pavement.

The adjustable linkage I made from a screen door tensioner nut (aluminum) which has both left and right hand threads. I cut the tension rods off at the thread line which left approximately 2" of threaded rod. I then cut two pieces of nylon approx 1"x1" and drilled a .375 hole in the middle to slip over the sensor lever boss. In the end of the nylon pieces I screwed the threaded rods and twisted the nut to achieve approximately 5.25" between the replacement linkage holes center. After driving the vehicle for a bit, I reached behind the tire and fine tuned the adjusting nut which made both sides of the vehicle equal. Tire air pressure being equal of course.
 
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