Auto Ride Problem

dmcglathery · January 23, 2011

I am also having issues with my air suspenssion on my 2001 Denali. I have replaced my compressor which was dead and both shocks which were cracked. My compressor still kicks on every time I start the truck and then shuts off. The compressor kicks back on about every minute. I am assuming the only thing left to replace would be the air hoses. Does anyone know where I can purchase new air hoses? The dealer didn't seem to be of any help.

Platinum1 · July 15, 2011

I have a 2000 Tahoe I just bought 4 shocks from Arnnot rear OEM and front Bilstein. Before my compressor was working find even though my old rear shock was gone to the dogs for awhile. everytiME I use to turn my truck on the compressor would come on now with the new shocks, the compressor doesnt comes on. IT ONLY MAKE A CLICK SOUND EVERYTIME I START MY TRUCK. I testit by running direct power and it works but once i put back on the truck ... it just click and doesnt turn on. I have now msg on my dashboard and my fuse is good. I talk to some one from Arnnot and they say it could be where the white and blue wire on the compressor since my old shock was bad for a long time.... is this true? if not can some one please HELP....

THANKS

medinab · July 20, 2011

OK, I found the suspension control module in the passenger side rear area behind the interior panel and under the rear HVAC blower.

When I ground the light blue wire on connector C2 - A10 the compressor runs which tells me that the automatic level control relay and the compressor are both working fine. I never found the relay but I guesss that it is now a moot point since it is working properly.

So now I need to find out why the suspension control module is not grounding the C2 - A10 output wire when it ought to be (heavy load on rear of truck). It looks like the suspension control module inputs that effect this are probably the left rear & right rear suspension position sensors (C3 - A5 & A7) and the pressure sensor (C2 - B5).

I now need to know how the suspension position sensors and the pressure sensor inputs effect the compressor relay output. It looks like all of the sensors use a 0-5vdc analog signal. Any help would be greatly appreciated.

medinab · July 20, 2011

Hi guys! I found this thread on Google so I joined the site to hopefully get some answers regarding the air ride system on my 2002 GMC Yukon XL Denali.

I replaced the complete compressor assembly (compressor, exhaust solenoid, dryer, pressure switch) as a complete unit last year and the system has worked fine until just this week.

I just tested the compressor by jumping 12v onto the red & black leads and it works fine. All three fuses that supply power to the entire system (IGN 3, Stud 1, & RTD) check out fine.

I have complete schematics of the system which show me that the red compressor wire is energized by the automatic level control relay (contact 87). The automatic level control relay (contact 30) is fed from the Stud 1 fuse under the hood. When the relay coil is energized, relay contacts 30 & 87 close to energize the red wire which feeds the compressor. The relay coil (contact 85) has + 12v supplied by a brown wire fed from fuse IGN 3 on the left side of the dash. The relay coil is energized when the other side of the coil (contact 86) receives a ground signal on the light blue wire fed from the suspension control module (connector C2 A10).

My problem is that do not know the location of the relay and the module. Can anybody please tell me where these two components are located?

I have one more question just out of curiosity. The orange wire fed from the RTD fuse under the hood is connected to one side of the exhaust soleniod coil. The other side of the coil is connected to a dark blue wire fed from connector C2 B5 on the suspension control module. My question is what is the purpose of the exhaust solenoid (purge water vapor?) and when does the suspension control module turn on this solenoid?

medinab · July 20, 2011

I found the main relay. It's under ther hood, attached to the side of the fuse box facing the engine. Hard to see as it's under the wiring harness but definitley the relay for the compressor pump/autoride.

Platinum1 · July 21, 2011

Can any one help me of did any have this problem.... Ihave a 2000 Tahoe(new body style) I bought new compresser and all ne shock but my compressor wouldnt come on. All I'm hearing when I start my truck is just a click in the compressor.

Please help..my last option now is to take it to the dealer and I dont have the money for it.

Thank you

jorkvilleyoe · July 31, 2011

Here is a link for the system as a whole far cheaper than gm's prices from the supplier for gm...hope this helps...the new compressor includes the necessary kit to rebuild the existing air dryer...

http://www.arnottindustries.com/part_GMC_A...id15_pid95.html

Spanky08 · February 15, 2014

I know this topic is old but i have a question, and i just cant find the answer to. I have an 08 tahoe i replaced the rear autoride compressor with an oem one, this is a complete unit. The unit is about a week old, when i installed it the system aired up with no problem, and the truck is at ride height. Its been a week and the compressor hasn't turn on again, the ride height is the same, is this normal?

godav · August 22, 2014

Does any one know the part number for the exhaust valve that is on the dryer. I have a 2008 Avalanche LTZ with auto ride. I want to replace the complete system but I can not find this valve/solenoid. Thank You Gary

gmtech4 · August 23, 2014

Does any one know the part number for the exhaust valve that is on the dryer. I have a 2008 Avalanche LTZ with auto ride. I want to replace the complete system but I can not find this valve/solenoid. Thank You Gary

dealer has the number

godav · August 23, 2014

I understand that the dealer would have the part number, but I was going to look for an aftermarket part.

Thank You

Gary

jamelfrazier · January 19, 2016

Pressure switch part 5846660 $8 to 20 bucks or buy a switch with a rebuilt drier for around 40 bucks on Ebay or Arrnott.com !

jamelfrazier · January 28, 2016

The ESC module has the ability to store DTCs as current or history codes. The system uses an ignition cycling diagnostic approach in order to reduce the occurrence of false or intermittent DTCs that do not affect the functionality of the system. This allows for the fail-soft actions to be taken whenever a malfunction condition is current, but requires the malfunction to be current for a certain number of ignition cycles before the corresponding malfunction code and message will be stored or displayed.

Automatic Level ControlThe Automatic Level Control (ALC) system maintains a desired rear suspension position under all types of towing, hauling and loading conditions. The system uses the Electronic Suspension Control Module (ESCM) and the serial data circuit to perform the system functions. When the vehicle is unloaded, the rear suspension is at a desired position, which is monitored by the ESCM using the position sensor inputs. As weight is added to the rear of the vehicle, the position sensor’s signal voltage inputs change.

When the ESCM detects a steady substantial change in the position sensor signal voltages for at least 10 seconds, it responds by commanding ON the ELC relay, which activates the compressor causing the air pressure in the shock absorber chambers to inflate. This inflation raises the rear of the vehicle to regain the desired suspension position. When weight is removed from the vehicle, the ESCM responds by commanding ON the exhaust valve causing the air pressure in the shock absorber chambers to deflate.

Each time the compressor is activated, the ESCM commands ON the exhaust valve for 1.5 seconds to release air from the compression chamber in the compressor’s cylinder head ensuring low motor current draw upon compressor activation. The ESCM also limits the amount of compressor run time to 255 seconds to protect the compressor components from thermal damage.

The system also performs a self test on each ignition ON cycle in which the ESCM commands the ELC relay ON, activating the compressor for 4 seconds then monitors the position sensor’s signal voltage inputs to verify the compressor is functioning and the system is holding air pressure.

Compressor ServiceThe compressor is a positive displacement piston air pump. The compressor draws filtered air through an intake line attached to an under body rail. The compressed air is then run through a dryer containing a moisture- absorbing chemical that dries the compressed air before it is sent to the shock absorber chambers.

The dryer should be cleaned and serviced during shock or compressor replacement. To service the dryer, remove the compressor assembly from the frame rail. The dryer twists apart and the desiccate beads and filter should be replaced. Service kits are available.

Trimset Recalibration

If the system is functioning abnormally, performing the Bumpstop and ALC Trimset recalibration procedures may correct the condition. When a system component has been replaced, the Bumpstop setup and ALC Trimset procedures must be performed.

1. Ensure that the vehicle has a full tank of fuel or add sufficient weight to the rear of the vehicle to simulate a full tank of fuel.

2. Place the vehicle on a flat level surface. Ensure that the suspension is in the normal resting position. With a scan tool, perform the ALC Trimset procedure by following the screen prompts.

3. With a scan tool, perform the suspension Bumpstop setup procedure by following the screen prompts. Once the process has been completed, the system should be fully functional.

Pressure TestChecking the integrity of this intelligent air ride system requires more than just soapy water. In order isolate a leak, the system must be at pressure. Since the system has solenoids, leaks may not be spotted until that circuit has been pressurized.

1. Disconnect the air tube from the air dryer.

2. Attach the air tube to the pressure gauge on the side opposite the toggle valve.

3. Close the toggle valve.

4. Apply service air pressure to the service valve and pressurize until the pressure gauge reads 550 kPa (80 psi).

5. Verify that the system maintains pressure for at least one minute. If the system does not maintain the specified pressure for the specified amount of time, check the shock absorber air sleeves, air tubes and all connections for air leaks using a soapy water solution. Repair or replace any leaking components.

rjplow1 · June 20, 2016

i have an o5 suburban put in a new compressor 2 years ago now not working again but this time there is no service air ride indicator coming on, will it hurt the truck to just not worry about it and let it just not work