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SRX 07 V8
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Discussion Starter #1 (Edited)
Hello members

While I made one post may as well write another, my rear compressor for the suspension never worked, pulled it out, not a hard job and connected it to 12 Volts and nothing, I actually would have been surprised if it did, it looks like a rusted corroded piece of junk!
Truck is a 2007 V8 with air suspension, but do I need it, I do not haul anything, just some people in the back(its a 7 seater) those seats in the very back were not made for anyone over 5 years old!!!, (The back seat middle is pretty hard after about 30 mins, the kids and their friends fight who's not going to sit in the middle OK getting off topic sorry) groceries, odds and ends. rear suspension is in good shape, no tears in rubber, no oily residue.
There is no sag. Truck is level all the time (at least looks level).
From what I have read on here, believe me I use the search. Its a noisy compressor anyway. I went to a used car lot just to hear one working,reminded me of the sound of a common garage compressor. If you were not familiar with the sound you might ask is something wrong with the truck?

So is this something the truck needs if one does no hauling with it, just light kids in the back, sometimes 2 adults and some occasional luggage. I mean its not like you put people in the back it sags to the wheels an never rises.
Should I just skip the 500 dollar investment and buy a fabulous BBQ grill?

It's actually a serious question, so please inputs appreciated

Thanks for looking,have a good summer
 

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SRX 07 V8
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230 Posts
Discussion Starter #2 (Edited)
Automatic Level Control Description and Operation
The automatic level control (ALC) system maintains a desired suspension position under all types of towing, hauling, and loading conditions.

The system uses the electronic suspension control module (ESCM), ELC relay, ALC compressor assembly, air dryer, air lines, shock absorbers with integral air chambers, suspension position sensors, exhaust valve, driver information center (DIC), and the serial data circuit to perform the system functions.

When the vehicle is unloaded, the suspension is at a desired position, which is monitored by the ESCM using the position sensor signal voltage inputs. As weight is added to the vehicle, the position sensor 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 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. This deflation lowers the vehicle to regain the desired suspension position.

The compressor is a positive displacement piston air pump driven by a 12-volt DC permanent magnet motor. 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. 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 signal voltage inputs to verify the compressor is functioning and the system is holding air pressure.

The ESCM has the ability to detect malfunctions within the ALC system. Any malfunctions detected will cause the DIC to display the SERVICE SUSPENSION SYSTEM message. For more information on other functions of the ESCM, refer to Electronic Suspension Control Description and Operation .
Wonder why my DIC (no pun) never showed malfunction if it has no compressor? All fuses are good

Electronic Suspension Control Description and Operation
Electronic Suspension Control Description

The electronic suspension control system, also known as the magneto-rheological real time damping (MRRTD) system independently controls the fluid viscosity in each of the 4 shock absorbers in order to control the vehicle ride characteristics. The electronic suspension control (ESC) system is capable of making these changes within milliseconds. The ESC system consists of the following major components:

• The electronic suspension (ESC) module
• The front/rear position sensors
• The front/rear adjustable shock absorbers
• The shock absorber electrical actuators, which are integrated within the shock absorbers
The ESC controls the damping mode selection according to the following factors:

• The vehicle speed
• The chassis pitch input
• The steering position
• The body to wheel displacement
The ESC module evaluates these inputs in order to separately control the shock absorbers, providing an enhanced ride and comfort level over the widest possible range of operating conditions.

Electronic Suspension Control Module

The electronic suspension control (ESC) module provides electronic control logic and output drive for each shock absorber. The ESC module makes decisions due to road and driving conditions based on various inputs. The ESC module receives input information by sensors that are directly connected to the ESC module or by other systems through the serial data line and uses these inputs to independently control the shock absorbers at each corner.

Electronic Suspension Control Position Sensors

The electronic suspension control (ESC) position sensors provide the ESC module with the body to wheel displacement input. The ESC module uses this and other inputs in order to control the stiffness of the shock absorber. If any body or wheel motion is detected, the ESC module will determine how soft or firm each shock absorber should be to provide the best ride. The ESC position sensors are mounted at each corner of the vehicle between the control arm and the body/frame.

Electronic Suspension Control Shock Absorber or Strut

The electronic suspension control (ESC) shock absorbers are monotube type which provide damping by increasing magnetic flux to magnetic particles to resist suspension movement. The ESC shock absorber has the capability of providing multiple modes or values of damping forces, in both compression and rebound direction. The damping forces are achieved by increasing or decreasing the magnetic flux to shock absorbers.

The front ESC actuator connector is located at the top of the shock absorber. The rear ESC actuator connector is at the top of the shock absorber.

Electronic Suspension Control Operation I guess this answers my above question, I assume no compressor will not trigger any signals, at least if you never haul anything or load the rear heavy

The electronic suspension control (ESC) system uses the information from other systems in order to execute certain functions.

The ESC system does not have a malfunction indicator lamp, but instead uses the instrument panel cluster (IPC) for the display functions. When the ESC system detects a malfunction that sets a DTC, the ESC system sends a message on the serial data line directly or through the powertrain control module (PCM) to the IPC, which will display one of the following messages:

• SHOCKS INOPERATIVE
• SERVICE SUSPENSION SYSTEM
• SPEED LIMITED
The SHOCKS INOPERATIVE message will only be displayed if the ESC system detects a malfunction that sets a DTC and causes the ESC system to disable all 4 shock absorbers. The ESC system will send a message on the serial data line to the IPC to display this message.

The SERVICE SUSPENSION SYSTEM message will only be displayed if the ESC system detects any malfunction that sets a DTC. The ESC system will send a message on the serial data line to the IPC to display this message.

The SPEED LIMITED message will only be displayed if the ESC system detects a malfunction that sets a DTC and causes the ESC system to disable all 4 shock absorbers. The ESC system will send a message on the serial data line to the PCM indicating that all 4 shock absorbers were disabled. The PCM then sends a message to the IPC to display this message.

The ESC module has the ability to store DTCs as current or history codes. Most ESC system malfunctions will display a message in the IPC and set a DTC. The message will remain ON until the RESET button is pressed on the driver information center (DIC). As long as the DTC is current, the message will be displayed after every ignition cycle and the RESET button must be pressed to bypass the message.

The ESC 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 ESC 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.

If the ESC detects a malfunction, the ESC system defaults with a fail-soft action. A fail-soft action refers to any specific action the ESC system takes in order to compensate for a detected malfunction. A typical ESC fail-soft action would be if the ESC system detects a malfunction with a shock absorber.
 

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05 srx awd v6 (gone), '07 GXP, 2010 li'l red wagon 3.6
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3,177 Posts
You've answered your own question, in short, no.
 

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2007 STS-V, 2005 STS 1SG, 2005 STS 1SC, 2004 SRX AWD MRC
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Should I just skip the 500 dollar investment and buy a fabulous BBQ grill?
I'd go with the BBQ grill, but if you use it excessively you may need the air suspension.

I swapped the third seat from my SRX to The Wife's. Mine had air and hers didn't. We took a 1400 mile trip a couple of months ago with 5 passengers + a 3 year old + luggage and had no noticeable rear sagging or bouncy rear end. BTW my 24 yr old daughter spent the entire trip in the third row and liked it, but she's 5'1
 

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SRX 07 V8
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Discussion Starter #5
Yes I usually keep looking on my own and post results for others. Always good to share info

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I'd go with the BBQ grill, but if you use it excessively you may need the air suspension.

I swapped the third seat from my SRX to The Wife's. Mine had air and hers didn't. We took a 1400 mile trip a couple of months ago with 5 passengers + a 3 year old + luggage and had no noticeable rear sagging or bouncy rear end. BTW my 24 yr old daughter spent the entire trip in the third row and liked it, but she's 5'1
Where did you put the luggage with third row up? Yes one 5' could sit alone,room to squirm around. I assume you took the trip with your wife's truck? If that's the case the suspension is different?
 

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08 STS4 V8 1SG & 04 SRX4 V8 & 01 Monte SS
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The SRX without air compressor uses nivomat self leveling shocks in the rear. Which is different from the MRC shocks.
FWIW my STS has the same MRC setup and a working compressor which I faintly hear run every time the car is started. So while you may not think your SRX has a sag to it with no compressor I'd bet there is but you're just used to it being the height that it is. A full tank of gas isn't light. And you've got 3rd row seat and probably the ultra view moonroof too which adds more weight to the car.
I'd look at fixing the compressor and possibly replacement of airlines and maybe even shocks too as it's possible you were leaking air and burned out the compressor. If that's too much for you then swap out to the self leveling nivomat shocks in the rear and bypass the MRC for the rear.
Having the car level is not just for looks. It is a safety concern and can also affect mileage.
 

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SRX 07 V8
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Discussion Starter #7
I will look around for some more SRX (which should be easy) for sale on lots and start them up, see if they are quiet, last one I tried was loud. as I mentioned so I assumed they all were, will rate 3 different ones. FWIW I see no difference in height full of empty tank, but as you say just use to it.

Any members can add if theirs are quiet or loud sort of a survey.
 

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2007 STS-V, 2005 STS 1SG, 2005 STS 1SC, 2004 SRX AWD MRC
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Where did you put the luggage with third row up? Yes one 5' could sit alone,room to squirm around. I assume you took the trip with your wife's truck? If that's the case the suspension is different?
The 3rd seat was adjusted forward and some luggage was tightly packed behind the seat and some was in the unused area of the 3rd seat. Mine has MRC with air shocks that don't work, hers is standard with no air shocks. No moonroof on either. The trip was in hers. There couldn't have been more than an inch difference in ride height.
Ludacrisvp, I'll take that 1sg off your hands anytime :stirpot:
 

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08 STS4 V8 1SG & 04 SRX4 V8 & 01 Monte SS
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I will look around for some more SRX (which should be easy) for sale on lots and start them up, see if they are quiet, last one I tried was loud.
It's possible the one you looked at had a loud one or was failing. MRC wasn't too common on the SRX from what I've seen on dealer lots so it may not be easy to find one with a compressor.

Mine has MRC with air shocks that don't work, hers is standard with no air shocks. No moonroof on either. The trip was in hers. There couldn't have been more than an inch difference in ride height.
Ludacrisvp, I'll take that 1sg off your hands anytime :stirpot:
I'm a bit surprised that you could get the MRC equipped SRX without the ultraview (which I feel is / was a big selling point for getting the SRX).
Then again another member on here has a 1SG STS with moonroof delete so I guess it happens.

If you compared the height of both cars as dead objects then they are off by an inch there ... After you drive a bit the nivomat shocks in the non MRC car pump themselves up to level the car which could end up being considerably more than an inch so it may be more accurate of a measurement to go drive a couple miles and come back and compare SRX with dead airbags on MRC and SRX with nivomat.

Based on your location I'm not sure you'll like or want a 1SG STS as its AWD only for that package. It sure does help in the rain though so maybe.... Not sure that I'd part with mine though, just finished installing the export rear fog lights this weekend on it to go along with my export tails and clear 3rd brake lamp.

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Nivomat in action
 

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2007 STS-V, 2005 STS 1SG, 2005 STS 1SC, 2004 SRX AWD MRC
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Based on your location I'm not sure you'll like or want a 1SG STS as its AWD only for that package. It sure does help in the rain though so maybe.... Not sure that I'd part with mine though, just finished installing the export rear fog lights this weekend on it to go along with my export tails and clear 3rd brake lamp.



You may be right about that. My SRX is AWD and The Wife's isn't. While mine has a higher top speed, her's has better acceleration and feels more nimble due to the lighter weight and less driveline drag. My STS is a well optioned 1SE, but still, 1SG....:drool:
 

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01 740iL, 99 Z28, 06 SRX V8 rwd
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I have an SRX that was originally equipped with MRC but has no sunroof - so it's possible, the options weren't linked.

Here's why the non MRC SRX with the swapped in 3rd row didn't sag when fully loaded on a road trip - non MRC SRXs, as far as I know, all have the other self leveling system, the Sachs Nivomat self leveling rear shocks. Which works wonderfully and can keep the rear perfectly level with a full load.
 
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