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LTZ Autoride

This issue REALLY makes no sense.  A sensor problem would not work when the truck is on, yet fail when the truck is off.  If the sensor is reading it wrong, or if the ride height is wrong, it wouldn't just change when the truck is turned off.

There has to be some sort of failure somewhere that is telling the computer to release the pressure.  I just don't have a clue as to what. 

Didn't someone report an issue like this once before (in this thread?)
 
Coopers_dad said:
Well, the soapy water showed massive leaks on the top and bottom of both bags. While under the truck I could hear my drivers side bag hissing.

Thanks to Amazon 2 new shocks will be at my place on Monday.

Lets hope the compressor doesn't give up now.

I going to bet the problem with your air compressor releasing air when you turn off the key is an air compressor that is worn out from trying to keep those leaky air shocks filled up since who knows when.
 
Cooper - change the shocks and see if the new ones still do this.  My thinking is that there is a check valve within the shock which is releasing when the truck is powered off.  I'm assuming this valve is failing. 

If the problem still persists with the new shocks, we'll have to keep pondering.
 
FYI: There is no checkvalve in the shocks, they either hold air or leak at the connector or thru the bags. Either is very easy to spot using soapwater.

If his is making the Whoosh Sound and instantly dropping only after key is turned off, then something is tripping the system into sending a signal to the exhaust valve to release the air...this could be checked using a voltmeter or light pen to verify its actually getting an electrical signal.

JohnnieMo said:
Cooper - change the shocks and see if the new ones still do this.  My thinking is that there is a check valve within the shock which is releasing when the truck is powered off.  I'm assuming this valve is failing. 

If the problem still persists with the new shocks, we'll have to keep pondering.
 
Well I pulled the trigger on the dorman compressor today. Hopefully that will solve my issue. Will report back on how it goes?.

bought this one?

DORMAN Part # 949001 {#20930288} Electronic Air Compressor
 
arizona-dave said:
FYI: There is no checkvalve in the shocks, they either hold air or leak at the connector or thru the bags. Either is very easy to spot using soapwater.

If his is making the Whoosh Sound and instantly dropping only after key is turned off, then something is tripping the system into sending a signal to the exhaust valve to release the air...this could be checked using a voltmeter or light pen to verify its actually getting an electrical signal.

What actually tells the system to release air?  I'm assuming "too much load" would be one reason.  "Overfilled" must be another.  Is there any other reason the computer would be releasing pressure?  A computer won't change its programming.  It either works or it doesn't.  So it must be a sensor or a moveable part somewhere that goes limp when the power turns off.  I just have no idea what.
 
I believe the controler module receives signal from the ride height sensor and the pressure sensor.

The system does have a maximum pressure, which it wont exceed - however that is both less than a few hindred lbs, and it wont allow it to go over that limit with ignition on.

In other words, it shouldnt be able to over-pressure with ignition on, and then only release when off...

I do know mine will vent with ignition off when I unload the hitch...so there must be some sensing going on and computer monitoring it even with key out...maybe its a time-limit, or maybe there is a "wake-up" command when a sensor see a change in height when unloading.

make sense?

In any case, it should not be venting just because key is turned off...mine held 1500lbs of rock overnight without loosing 1/16th inch of height, and that had to be some serious PSI going on.

JohnnieMo said:
What actually tells the system to release air?  I'm assuming "too much load" would be one reason.  "Overfilled" must be another.  Is there any other reason the computer would be releasing pressure?  A computer won't change its programming.  It either works or it doesn't.  So it must be a sensor or a moveable part somewhere that goes limp when the power turns off.  I just have no idea what.
 
arizona-dave said:
I do know mine will vent with ignition off when I unload the hitch...so there must be some sensing going on and computer monitoring it even with key out...maybe its a time-limit, or maybe there is a "wake-up" command when a sensor see a change in height when unloading.


^ I can confirm that as well. I have had a load in the truck while running. Turn the truck off, unload, and the system will vent out the 'extra' air from the bags that isn't needed.


 
Seems to me its even vented when I unload after the truck has been off for a while (like 30+ minutes)...Ive never really timed it, but I know it wasnt just 30 seconds.

It will also vent when running and I unload a lot of weight.

blu_fuz said:
^ I can confirm that as well. I have had a load in the truck while running. Turn the truck off, unload, and the system will vent out the 'extra' air from the bags that isn't needed.
 
I used to tell people that the auto-leveling suspension was great, but NOT heavy duty.  Given what you have tested, I no longer say that.  It is seriously heavy duty when its working properly. 

I have to retest mine this spring to see if I have any other leaks.  The compressor still runs more often than I think it should.

 
I'm still having problems with mine. Slow leak somewhere (empty bags after 3-5 days) and "service suspension" light comes on and compressor runs for 3 seconds every time I start the truck.


I'm just trying to save up enough money to take it in to be fixed. Its probably a ride sensor, I dunno anymore  :beating:
 
My compressor just gave up so it's time to get some work done. I guess I'll change the compressor then check for leaks. I really didn't notice it run much at all so hopefully it's just the compressor.  :E:
 
JohnnieMo said:
I used to tell people that the auto-leveling suspension was great, but NOT heavy duty.  Given what you have tested, I no longer say that.  It is seriously heavy duty when its working properly. 

I have to retest mine this spring to see if I have any other leaks.  The compressor still runs more often than I think it should.

This is what mine is doing. I think the compressor is just worn out.
 
With the amount of boulders I had in mine last, Id have to agree...when working properly, this thing is pretty Heavy Duty.

I will get to test it with the trailer soon enough...that will put the mettle to the test, if it holds air up the mountain, then Im gunna have to say its "Very Heavy Duty".

Nothing lasts forever, and all working parts wear out, just like brakes. 75-90K miles imho seems like a decent life span for shocks that get fairly abused...


JohnnieMo said:
I used to tell people that the auto-leveling suspension was great, but NOT heavy duty.  Given what you have tested, I no longer say that.  It is seriously heavy duty when its working properly. 

I have to retest mine this spring to see if I have any other leaks.  The compressor still runs more often than I think it should.
 
Coopers_dad said:
My passenger side shock had a different clip holding the air line in place which I reused but will replace when I can figure out the part number.


^ My '07 also had a different clip that holds the air line to the shock. It was plastic VS metal like all the other ones. So they must come factory like that on some trucks for some reason....?


Glad to hear the swap went quick, and I'm glad you went with the "leave the wheels on" method because it is the easiest and quickest way to swap the shocks. Nice job.
 
Any of you guys have any tips on changing the compressor out? Mine will be here friday and haven't really seen much info on those. I have yet to crawl under and really study anything other than shocks when I changed them so its a bit intimidating.
 
Very easy, and don't worry about the shocks/truck dropping down.


Climb under the drivers side rear wheel. Pop some of the pressure tree buttons out to flip the rubber away from the compressor. Unhook the big block shaped harness. Use a TORX head bit and remove the 4 torx bolts holding the compressor to the truck. Drop the compressor a little so you can get your hand up around it. Twist the metal air line clip 90* and pop the air line off the dryer canister. Pull the rubber hose off the compressor pump (clean air intake tube). Wiggle it out, done.
 
OK.

You will probably still have to take the original unit out of the bracket to access the bracket bolts where they go through the frame.

Same with your new unit, probably have to take it off the bracket to mount the bracket to the truck.
 
Changed the compressor out in about 15 min. 3-13mm nuts, one electrical connector, unhook airline from driver shock, unhook passenger side airline from the "T" on the compressor, pop christmas tree clip loosed that holds the drier, pull the entire unit down. The dorman unit is as loud as my stock one so maybe it wasn't as loud as I thought. I was very pleased with the fit and finish of the dorman set up, looked just like the OEM. I don't know how long it will hold up but, it has a limited lifetime warranty. I usually don't buy aftermarket parts so it was a nice surprise to see how close it was to oem.

Keep in mind, I bought the entire unit new. Part number is on the previous page. I did not have to take anything a part, just the nuts holding the bracket to the frame.

 
My Pass side is also a plastic clip, drivers metal.

No idea why came from factory like that. Maybe a study/test to see if the plastic ones lasted.

Incredibly they do.

blu_fuz said:
^ My '07 also had a different clip that holds the air line to the shock. It was plastic VS metal like all the other ones. So they must come factory like that on some trucks for some reason....?


Glad to hear the swap went quick, and I'm glad you went with the "leave the wheels on" method because it is the easiest and quickest way to swap the shocks. Nice job.
 
90 mins is a LONG grocery stop :) lol

Nice that they are holding!

Coopers_dad said:
Just an update.  Pulled my 29ft trailer camping this weekend went 300miles in total with zero issues.  The bags pumped up fine with the weight and held it without leaking with the truck off for 90 minutes while we went grocery shopping.  Pulls much better now. (y)
 
1) Beer - Check

2) Meat - Check

3) Chips - Check

Checkout time! LOL

PS: 4) CHECK Airbags - Check.

Coopers_dad said:
90 is a VERY long time.  My wife likes to search out the deals which means going down every single isle slowly and methodically. :E:  I prefer the parameter attack method.  Fruit, Veg, Meat, Beer Checkout.
 
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