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explain magnetic shocks

Tbirdusa

Active Member
Joined
Apr 20, 2009
Messages
25
Location
Kansas City, MO
I don't get it.... Can somebody explain what the magnetic ride control is on this car? I've got a bit of a squeek in the back driver side and it sounds like a dry shock boot.
 

Popbigguy

Seasoned Member
Joined
Oct 17, 2008
Messages
705
Location
Lincoln, NE
My XLR/V(s)
2007 XLR-V RII'07 RIII'08 SA'09 CO'10 NCSC'11 PA'12 BG'13 MT'14 VBOBX'15
I think,,,,, it has to do with the fluid in the shocks. To stiffen the ride, like when in performance mode, a electical charge is sent to the shocks, the fluid gets "thicker" hence you get a stiffer shock. I assume a computer onboard, adjusts the electrical charge going to the shocks to adjust how stiff the shocks has to be at any set time. The noise you have may also be a bushing in the suspension and not the shocks.
 

ccclarke

Seasoned Member
Joined
Sep 17, 2008
Messages
1,032
Location
Uncanny Valley, New England
My XLR/V(s)
2013 Graphite Metallic XTS Platinum
Suspension Position Sensors at each wheel measure wheel travel and a varying voltage is sent to each Suspension Damper (shock) to adjust the viscosity of the fluid. This happens roughly every milli-second, so your suspension is adjusted 1000 times a second. Pretty cool stuff.

Have someone press down on the car a few times at the rear corners to help isolate where the offending noise is originating from.

CC :wave:
 

HOMEGAMEROOM

Guest
Joined
Oct 16, 2008
Messages
1,255
Location
Georgia
My XLR/V(s)
2004 Light Platinum, President, "Midwest Marauders"
From the repair manual:

Electronic Suspension Control Description and Operation

<A href="http://127.0.0.1:9001/servlets/BlobShtml?ShtmlFile=907638&evc=sm&pubid=423&cellId=73558&mspsdsubkey=2705#ss1-907638">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 four shock absorbers in order to control the vehicle ride characteristics. The 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.
<A href="http://127.0.0.1:9001/servlets/BlobShtml?ShtmlFile=907638&evc=sm&pubid=423&cellId=73558&mspsdsubkey=2705#ss2-907638">Electronic Suspension Control Module

The 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.
The ESC module uses these inputs in order to independently control the shock absorbers at each corner. The ESC module is located in the LH rear storage.
<A href="http://127.0.0.1:9001/servlets/BlobShtml?ShtmlFile=907638&evc=sm&pubid=423&cellId=73558&mspsdsubkey=2705#ss3-907638">Electronic Suspension Control Position Sensors

The 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.
<A href="http://127.0.0.1:9001/servlets/BlobShtml?ShtmlFile=907638&evc=sm&pubid=423&cellId=73558&mspsdsubkey=2705#ss4-907638">Electronic Suspension Control Shock Absorber or Strut

The 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. The rear shock absorbers have jumper harnesses for ease of maintenance.
<A href="http://127.0.0.1:9001/servlets/BlobShtml?ShtmlFile=907638&evc=sm&pubid=423&cellId=73558&mspsdsubkey=2705#ss5-907638">Electronic Suspension Control Operation

The 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 PCM to the IPC, which will display one of the following messages:
  • SHOCKS INOPERATIVE
  • SERVICE RIDE CONTROL
  • MAXIMUM SPEED 129 km/h (80 mph)
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 four shock absorbers. The ESC system will send a message on the serial data line to the IPC to display this message.
The SERVICE RIDE CONTROL 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 MAXIMUM SPEED message will only be displayed if the ESC system detects a malfunction that sets a DTC and causes the ESC system to disable all four shock absorbers. The ESC system will send a message on the serial data line to the PCM indicating that all four 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 diagnostic trouble codes (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, the ESC system will ignore this input and fail-soft to the TOUR ride setting.
It is possible for a suspension position sensor to become stuck. This fault would not be detected by the ESC module, therefore a DTC would not be set and no message would be displayed by the IPC. This fault is addressed under Symptoms - Electronic Suspension Control.
 

Rob

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