What if my rear drops on my load leveling suspension on 2004 gmce nvoy

Air Suspension ??????

Air Suspension Description and Operation
Air Suspension
The primary mission of the Air Suspension System is the following for the rear suspension under loaded and unloaded conditions:
• Keep the vehicle visually level
• Provide optimal headlight aiming
• Maintain optimal ride height
The Air Suspension System consists of the following items:
• Air suspension compressor assembly
• Air suspension sensors
• Rear air springs
Important: The Air Suspension System must have a voltage supply of at least 12.6V to operate properly.
The Air Suspension System will maintain the rear D height within 4 mm (0.15 in) in all loading conditions and the leveling function will deactivate if the vehicle is overloaded. The side to side D height variation is maintained within 8 mm (0.31 in). After ignition is turned off, the air suspension control module (ASCM) will remain active for between 30 minutes and 2 1/2 hours. The system will exhaust pressure within 30 minutes after the ignition is turned off to lower the vehicle after unloading. In a temperature-controlled environment, the leakage of the complete load leveling system will not result in more than 1.4 mm (0.05 in) drop of rear suspension height at GVWR during a 24 hour period. If the outdoor temperature drops from +20°C (+68°F) to -5°C (+23°F), the rear D height may drop as much as 25 mm (1 in). However, the Air Suspension System should return to the specified D height when the ignition is again cycled to ON.

What is the problem ?

Diagnostic Trouble Code (DTC) Displaying
The Air Suspension system has an internal clock to prevent overheating if the compressor assembly is running for a prolonged period of time. If the system overheats, all leveling function stops until the system cools down. During this time, the indicator LED on the air inflator switch will be quickly flashing at a constant rate.
The other three diagnostic trouble codes are displayed with a blink code on the inflator switch LED. The Air Suspension Compressor Assembly shall begin to indicate the code when the condition to cause the code becomes current.
The number of the fault code shall be represented by the number of flashing pulses on the inflator switch LED. The flashing pulses shall have a repetition rate of 0.5 seconds and each code shall be separated by a 3.0 second delay. All codes shall be flashed in the order of occurrence of the fault. The blink code shall take priority over other processes that have access to the inflator switch LED. Refer to the following:
• DTC 001
• DTC 002
• DTC 003

Trim Height Uneven or Low ??????

Search Results

1. 2004 Prado Grande Air Suspension Problem - PradoPoint

   www.pradopoint.com > ... > Suspension (120 Series) Dec 18, 2012 - 15 posts - ‎8 authors Found rear suspension not working Hi - Lo / auto level not working at all. Show toToyota dealer, informed air compressor faulty need replacement, but they do ... I have a2003 grande and the same symptoms as mentioned;

check for leaks in the lines, also check to see if the shocks have air leaks.

If you have Air suspension this can happen. The noise you hear like from an engine is actually the airpump trying to keep up.

The hissing is air escaping and the bouncing is an indication that the suspension is not fully inflated.

There are individual bleed valves so the system can be leveled by itself. The valve on one suspension unit may be leaking. Sometimes soapy water sprayed while the part is working and again while shut off will show a leak.

Some Makes have a diagnostic plug which a scanner can read to find the problem. Often a car is jacked or lifted on a rack and someone did not turn off the Air system and knocked it out of alignment.

I hope my solution is helpful and enables you to diagnose the problem now.

There has been a service bulletin for that type of concern. Here is what it states.









Suspension - Rear Suspension Is Low/Sagging/Uneven

Notes




ENGINEERING INFORMATION

Bulletin No.: 06-03-09-006B

Date: December 15, 2008
Subject:
EI06006 - Rear Suspension Uneven, Sagging, Low (Recalibrate Air Spring Sensor)

Models:
2006-2007 Buick Rainier
2006-2007 Chevrolet TrailBlazer SS
2006-2007 GMC Envoy, Envoy XL
2006-2007 Saab 9-7X


with Suspension Pkg - Rear Load Leveling (RPO G67)

Supercede:

This bulletin is being revised to update the labor operation in the warranty information. Please discard Corporate Bulletin Number 06-03-09-006A (Section 03 - Suspension).

Condition

Some customers may comment on the rear suspension being uneven or sagging.

Correction

DO NOT REPLACE THE COMPRESSOR.

Based on technician feedback, engineering has determined that the customer's concern can be corrected by recalibrating the air spring sensor. Refer to the Trim Height Uneven or Low diagnostics and Air Spring Sensor Calibration procedure found in SI.

If the spring is bowed down it would provide no load support, only adding height ot the suspension. It's possible the previous owner flipped the springs over to drop the rear of the truck or to soften the suspension a little. Go to a dealership and observe th new trucks. If they all frown, your ok.

Sounds like air suspension bag leaking. (bag instead of spring) You can convert the car over to springs again, which are much cheaper then bags, but it will not have the load leveling capabilites that it used to have. The bags cost my local repair shop $168 EACH to buy (at his discounted price from the dealer.) It literally takes about 12 minutes to change the bags on each side! It is weird to look at them when you get it off. You will find dryrot cracks which when full inflated they seem to stop leaking. But the next morning, after a cold evening, the rear end will be all the way down.

I found it destroys the rear shock if driven very far when this condition occurs. I ONLY changed my rear shock to the KYB Gas Adjust, which the auto parts store will tell you they are not applicable to your car, but if you call KYB they will give the part number too you. However, I REGRET not having changed my front struts to the same spec KYB upgraded struts to match the rear upgrade.

it is a compressor that pumps up the air shocks on rear of vehicle.it has a level sensor on suspension and when you load it the compressor will kick on to adjust vehicle height

there is a switch in the rear to turn air ride off whe vehicle is jacked up there isnt an enormous amount of pressure so when you undo the air lines you will be ok just make sure air ride switch is in off position

your shocks dampen the movement and up and down flow or you suspension. it is may be a bad coil spring