Where is the rear suspension sensor located what does it look like

Turn Off Suspension Switch Before Jacking/Lifting Vehicle ...

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Turn Off Air Suspension System Before Jacking/Lifting Vehicle on Lincoln Navigator. Prior to jacking or lifting a vehicle with air suspension, you must turn off thesuspension switch. The switch is generally located in the trunk or on the right side of the passenger foot well. RepairPal Verified.

GMC Envoy Air Suspension Sensor - YouTube

? 4:25
https://www.youtube.com/watch?v=mh8rieTxFEM
Sep 27, 2013 - Uploaded by klondikerabbit
In this video, I am trying to diagnose and adjust the rear air suspension sensors on a 2003 GMC Envoy. The ... images for envoy where is the air suspension switch

Having it hooked up to a factory scan tool would be your best bet . Check for DTC'S diagnostic trouble codes . Without testing ,code scan ,we'd only be guessing .
Very complex , the untrained person hasn't got a pray of fixing this . You have no idea what your dealing with . Vehicle Dynamic Suspension The vehicle dynamic suspension consists of the following components:

• Rear air suspension control (RAS) module (5A919)
• Snorkel
• Drier
• Air compressor (5319)
• Air suspension switch (5K761)
• Solenoid valve (5311)
• Air spring (5560)
• Air suspension height sensor (5359)
• Air line
• Rear Air Suspension Control Module
  A microprocessor controls the air suspension system. The microprocessor and its supporting hardware are contained in the rear air suspension control module. The rear air suspension control module responds to signals from various sensors in the vehicle to maintain the programmed ride height while the vehicle is either moving or stopped. The rear air suspension control module accomplishes this by opening and closing solenoid valves to control the amount of air in the air spring(s). The rear air suspension control module turns on the compressor by applying voltage through the compressor relay to inflate the air spring(s) and raise the vehicle. The rear air suspension control module opens the vent solenoid to lower the vehicle by releasing air from the air spring(s) in response to signal inputs from the air suspension height sensor(s).
• Rear Air Suspension Control Module Diagnostic Trouble Code (DTC) Index DTC Description Source Action B1317 Battery Voltage High Rear Air Suspension Control Module GO to Pinpoint Test C . B1318 Battery Voltage Low Rear Air Suspension Control Module GO to Pinpoint Test C . B1342 ECU Is Defective Rear Air Suspension Control Module INSTALL a new rear air suspension control module. REFER to Module-Air Suspension Control . TEST the system for normal operation. C1441 Steering Sensor Channel A Circuit Failure Rear Air Suspension Control Module REFER to Section 211-00 . C1442 Steering Sensor Channel B Circuit Failure Rear Air Suspension Control Module REFER to Section 211-00 . C1722 Air Suspension Height Sensor Power Circuit Short to Power Rear Air Suspension Control Module GO to Pinpoint Test D . C1723 Air Suspension Height Sensor Power Circuit Short to Ground Rear Air Suspension Control Module GO to Pinpoint Test E . C1760 Air Suspension Rear Height Sensor High Signal Circuit Failure Rear Air Suspension Control Module GO to Pinpoint Test F . C1763 Air Suspension Rear Height Sensor High Signal Circuit Short to Ground Rear Air Suspension Control Module GO to Pinpoint Test G . C1765 Air Suspension Rear Height Sensor Low Signal Circuit Failure Rear Air Suspension Control Module GO to Pinpoint Test F . C1768 Air Suspension Rear Height Sensor Low Signal Circuit Short to Ground Rear Air Suspension Control Module GO to Pinpoint Test H . C1770 Air Suspension Vent Solenoid Output Circuit Failure Rear Air Suspension Control Module GO to Pinpoint Test I . C1773 Air Suspension Vent Solenoid Output Circuit Short to Ground Rear Air Suspension Control Module GO to Pinpoint Test J . C1790 Air Suspension LR Air Spring Solenoid Output Circuit Failure Rear Air Suspension Control Module GO to Pinpoint Test K . C1793 Air Suspension LR Air Spring Solenoid Output Circuit Short to Ground Rear Air Suspension Control Module GO to Pinpoint Test L . C1795 Air Suspension RR Air Spring Solenoid Output Circuit Failure Rear Air Suspension Control Module GO to Pinpoint Test M . C1798 Air Suspension RR Air Spring Solenoid Output Circuit Short to Ground Rear Air Suspension Control Module GO to Pinpoint Test N . C1813 Air Suspension Vent Request Exceeded Max Timing Rear Air Suspension Control Module GO to Pinpoint Test O . C1818 Air Suspension Air Compressor Request Exceeded Max Timing Rear Air Suspension Control Module GO to Pinpoint Test P . C1830 Air Compressor Relay Circuit Failure Rear Air Suspension Control Module GO to Pinpoint Test Q . C1832 Air Compressor Relay Circuit Short to Power Rear Air Suspension Control Module GO to Pinpoint Test R . C1840 Air Suspension Switch Circuit Failure Rear Air Suspension Control Module GO to Pinpoint Test S . C1842 Air Suspension Switch Circuit Short to Power Rear Air Suspension Control Module GO to Pinpoint Test D . C1897 Steering VAPS Circuit Loop Failure Rear Air Suspension Control Module REFER to Section 211-00 . U1041 SPC Invalid or Missing Data for Vehicle Speed

There is an air compressor mountedmabove the rear suspension. The fuse for the air ride suspension is located behind the trunk rear trim panel. There is a level sensor on the rear control arm. If fuse is good, check for power at plug feeding compressor, compressor failure common. With suspesion at low position, sensor should send power to compressor. if no power suspect height sensor. Check relay for power and operation although failure rare.

start here

The air suspension system is designed to improve ride, handling and general vehicle performance for static, on-road and off-road driving condition:

• Ride is improved by using an air type spring (the soft ride is inherent).
• Handling is improved by maintaining constant vehicle attitude.

The system consists of unique rear air springs, air compressor, air lines, air spring solenoids, height sensor, air suspension control module, attachments and associated signals derived from both driver and road inputs. With these components and signals, the air suspension control module commands changes in vehicle height that are necessary for the load leveling features.
The load leveling feature rear air suspension (RAS) systems shall automatically make adjustments in vehicle height so that the vehicle is always at trim height and constant front-to-rear vehicle attitudes are maintained over the expected load range of the vehicle. Adjustments in height that are necessary to correct height differences between the vehicle's left and right sides for RAS system shall be restricted to what can be reliably achieved with one air suspension height sensor.
The system uses one air suspension height sensor, a steering sensor, generic electronic module (GEM) transfer case inputs, and other vehicle sensors to measure driver and road inputs. The system changes vehicle height using an air compressor, two air lines, and the use of an air spring with an air spring solenoid.
The air suspension system holds vehicle height when the rear hatch or any door is opened. The system stores rear vehicle height the moment any open door is detected. The system then maintains this height regardless of the addition or removal of a load. The system will return to its commanded height when all doors are closed and the vehicle speed exceeds 16 km/h (10 mph).
Air Suspension Switch
The air suspension switch is located behind the RH kick panel on a mounting bracket. The switch interrupts power to the air suspension control module.
The air suspension switch supplies a signal to the air suspension control module. Without the air suspension control module receiving this signal the load leveling system is inoperative and will not react when rear of the vehicle is raised or lowered. If the air suspension system is disabled by turning off air suspension switch, a "CHECK SUSP" will appear in the RH corner of the instrument cluster with the ignition in the run position.
Air Compressor
The RAS air compressor:

• Is not interchangeable with four wheel air suspension (4WAS) compressor.
• Consists of the compressor and vent solenoid; neither are replaceable as individual items.
• Is mounted in the engine compartment between the washer fluid bottle and headlamp (RH front corner).
• Is a single cylinder electric motor driven unit that provides pressurized air as required.
• Is powered by a solid state relay, controlled by the air suspension control module.
• Passes pressurized air through the compressor air drier that contains silica gel (a drying agent). Moisture is then removed from the compressor air drier when vented air passes out of the system during vent operation.
• Air drier has a single port and is not interchangeable with 4WAS compressor air drier.
• Air drier may be replaced separately.
• Incorporates a snorkle that may be replaced separately.

The vent solenoid:

• Allows air to escape from the system during venting actions.
• Is located in the air compressor cylinder head.
• Has a 160 psi internal relief valve.
• Shares a common electrical connector with the air compressor motor.
• Is enclosed in the cylinder head casting, which forms an integral valve housing that allows the valve tip to enter the pressurized side of the system.
• Has an O-ring seal that prevents air leakage past the valve tip.
• Opens when the air suspension control module determines lowering is required.
• Provides an escape route for pressurized air that opens when system pressures exceed safe operating levels.
• Is replaced with the air compressor as a unit.

Air Spring
RAS vehicles use air springs in the rear. The air springs provide a varying spring rate proportional to the systems air pressure and volume. The air suspension system regulates the air pressure in each air spring by compressing and venting the system air. Increasing air pressure (compressing) raises the rear of the vehicle while decreasing air pressure (venting) lowers the rear of the vehicle. Vehicle height is maintained by the addition and removal of air in each air spring through an air spring solenoid installed in the upper spring cap and energized through the air suspension control module.
The air springs are mounted between the axle spring seats and the frame upper spring seats.
The two air springs replace the conventional rear coil springs.
Air Suspension Height Sensor
When the air suspension height sensor indicates that the rear of the vehicle is lower than trim under normal driving conditions, the air compressor will turn on and pump compressed air to the air springs. When the sensor indicates that the rear of the vehicle is raised above trim under normal driving conditions, this will cause the air to be vented from the air springs to lower the vehicle back to its trim height level.
One air suspension height sensor is mounted on the vehicle. The air suspension height sensor sends a voltage signal to the air suspension control module. The output ranges from approximately 4.75 volts at minimum height (when the vehicle is low or in full jounce), to 0.25 volts at maximum height (when the vehicle is high or in full rebound). The air suspension height sensor has a useable range of 80 mm (3 in) compared to total suspension travel of 200-250 mm (8 to 10 in) at the wheel. Therefore, the air suspension height sensor is mounted to the suspension at a point where full rear suspension travel at the wheel is relative to 80 mm of travel at the air suspension height sensor. The air suspension height sensor is attached between the No. 5 frame crossmember (upper socket) and the panhard rod (lower socket). Replace the air suspension height sensor as a unit.
Compressor Relay
The compressor relay is energized by the air suspension control module to allow high current to flow from the battery to the compressor motor.

• A solid state relay is used in the air suspension system for air compressor control. The relay incorporates a custom power metal oxide semi-conductor field effect transistor (MOSFET) and ceramic hybrid circuitry. The relay switches high current loads in response to low power signals and is controlled by the logic of the air suspension control module.

Air Suspension Control Module
NOTE: The 4WAS air suspension control module is used for the RAS system. The internal processor recognizes external circuitry to determine if it is installed in a 4WAS or a RAS equipped vehicle.
NOTE: The air suspension control module is calibrated with information from the air suspension height sensor. A new or exchanged air suspension control module requires a ride height adjustment calibration process to be performed.
The air suspension control module controls the air compressor motor (through a solid state relay), and the air spring solenoids. The air suspension control module also provides power to the air suspension height sensor. The air suspension control module controls vehicle height adjustments by monitoring the air suspension height sensor, vehicle speed, a steering sensor, acceleration input, the door ajar signal, transfer case signals, and the brake pedal position (BPP) switch. The air suspension control module also conducts all fail-safe and diagnostic strategies and contains self-test and communication software for testing of the vehicle and related components.
The air suspension control module is mounted in the passenger compartment inside the instrument panel above the radio and temperature controls.
The air suspension control module monitors and controls the air suspension system through a 32-pin two-way connector. The air suspension control module is keyed so that the air suspension control module cannot be plugged into an incorrect harness. There are two sides of the harness connection to the air suspension control module. Each is uniquely colored and keyed to prevent reversing the connections.
Air Suspension Diagnostic Connector
The air suspension diagnostic connector is used to aid the technician in diagnosing the air suspension system. It is also used to vent the system of compressed air when air suspension system components need to be repaired or replaced. The air suspension diagnostic connector is located under steering column.

Vehicle Dynamic Suspension The vehicle dynamic suspension consists of the following components:

• Rear air suspension control (RAS) module (5A919)
• Snorkel
• Drier
• Air compressor (5319)
• Air suspension switch (5K761)
• Solenoid valve (5311)
• Air spring (5560)
• Air suspension height sensor (5359)
• Air line

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Visual Inspection Chart Mechanical Electrical

• Restricted suspension movement
• Excessive vehicle load
• Cut, severed, or crimped air line(s)
• Damaged air spring(s)
• Height sensor damage
• Height sensor mounted incorrectly, disconnected, or damaged

• Central junction box (CJB):
  • Fuse 5 (15A)
• Battery junction box (BJB):
  • Fuse 8 (30A)
• Loose or corroded connectors
• Air suspension switch OFF

The air suspension control module is diagnosed using Super Star II Tester 418-F045 (007-0041B) or equivalent.
The test connector used to communicate with the air suspension control module is located on the RH side of the luggage compartment.
When the tester is connected, the engine is started and the HOLD/TEST button is latched down, the air suspension control module will respond sending a code 10 to the Super Star II Tester which represents "Diagnostics mode entered." If diagnostic trouble code (DTC) 10 is not displayed, go to Pinpoint Test A.
Air Suspension Control Module Diagnostic Trouble Code (DTC) Index
Condition Possible Sources Action

• No communication with the air suspension control module

• CJB Fuse 5 (15A).
• BJB Fuse 8 (30A).
• Circuitry.
• Air suspension control module.

• GO to Pinpoint Test A .

• Unable to enter auto test

• Air suspension control module.
• Circuitry.

• GO to Pinpoint Test B .

• Rear air suspension does not respond to load changes

• Circuitry.
• Air compressor.
• Air compressor inlet tube.
• Air compressor drier.
• Air suspension height sensor.
• Air suspension control module.

• GO to Pinpoint Test C .

• Rear rides low/high

• Circuitry.
• Air spring solenoid.
• Air suspension height sensor.
• Air suspension control module.

• GO to Pinpoint Test C .

• Poor ride quality

• Circuitry.
• Air springs.

• GO to Pinpoint Test C .

• Air suspension warning indicator ON

• Air suspension switch OFF.

• Place the air suspension switch in the ON position.

• Air suspension control module.
• Circuitry.

• GO to Auto Test.

• Instrument cluster (conventional cluster) or lamp warning module (electronic cluster).

• REFER to Section 413-01A (conventional cluster) or REFER to Section 413-01B (electronic cluster), or REFER to Section 413-01C (natural gas cluster).

2001 Pontiac Grand Am 2.4L SFI DOHC 4cyl

Vehicle Speed Sensor - Location:
The speed sensors are built right into the wheel bearings of your vehicle, at the front and rear locations. They work both with the anti-lock brakes and with the traction control systems on the vehicle.

Removal & Installation
Front
The front wheel speed sensor is part of the hub/bearing assembly. Refer to Wheel Hub and Bearing Replacement in Front Suspension for service procedures.
Rear
The rear wheel speed sensor is part of the hub/bearing assembly. Refer to Wheel Hub and Bearing Replacement in Rear Suspension for service procedures.

I hope help you with this (remember rated this help) Have a nice day, good luck.

Description and Operation The rear air suspension:

• Is an air-operated, microprocessor-controlled, suspension system.
• Replaces the conventional rear coil spring suspension.
• Provides low spring rates for improved ride and automatic rear load leveling.
• Is standard equipment on the Town Car.
• Is available as optional equipment on Crown Victoria and Grand Marquis.

The rear air suspension system has the following features:

• The system is operational with the ignition switch in the RUN position.
• Automatic rear load leveling has limited operation for one hour after ignition switch is turned to OFF.
• The air suspension switch, located on the right side of the luggage compartment, must be turned OFF when the vehicle is on a hoist, being towed or jump started.
• The Air Suspension warning indicator is located in the instrument panel, to the right of the speedometer.
  • The warning indicator flashes five times and then stays on when service switch is turned off or a system malfunction is detected.
• The rear leveling system operates by adding or removing air in the springs to maintain the level of the vehicle at a predetermined rear suspension D ride height dimension, and is controlled by a control module (5A919) .
• The rear air suspension control module also controls the electronic variable orifice (EVO) steering.
• Refer to Section 11-02 for Description of the EVO steering system.
• Air required for leveling the vehicle is distributed from the air compressor to the rear air springs by a nylon air line which runs from the compressor air dryer (5346) through a Y-fitting to each individual air spring.

Suspension, Computer Controlled—Town Car


Item Part Number Description 1 9C392 Compressor Relay Power Junction Block 2 5A897 Air Line (Attached to Brake/Fuel Bundle) 3 5319 Air Compressor With Regenerative Air Dryer and Vent Solenoid 4 5A897 Air Line to Compressor 5 5K761 Air Suspension Service Switch 6 14489 Data Link Connector 7 — Quick Connect 8 — To LH Air Spring 9 — From Compressor 10 — Y-Fitting (Part of 5A911) 11 — To RH Air Spring 12 5A908 Heat Shield 13 5A966 Spring Retainer Clip 14 5560 Rear Spring 15 5359 RearAir Suspension Height Sensor 16 5A919 Control Module 17 14018 Air Spring Solenoid

Control Module Power and Ground The control module (5A919) has the following features:

• Power is provided by Circuit 418 and is controlled by the air suspension switch.
  • The air suspension switch is powered through a 15 amp fuse in Circuit 296 in Town Car.
  • AIR SUSPN PUMP (30A MAXI) fuse provides this power through Circuit 414 in the Crown Victoria/Grand Marquis.
• Control module ground is provided through control module wire harness Pins 6 and 21, to the RH inner quarter panel sheet metal, near the control module .

---------------------------------
Weight Added When weight is added to the vehicle:

• The air suspension height sensor (5359) length is reduced from trim length, sending a "rear is low" signal to the control module (5A919).
• The control module then turns the compressor on by grounding the compressor relay control Circuit 420. This restores the rear of the vehicle to trim position.
  • Battery voltage is provided to the relay coil by Circuit 414.
• The control module opens the spring solenoid valves (5311) by switching Circuits 416 and 429 to ground. This allows pressurized air to enter the springs.
  • Battery voltage is provided to the air spring solenoid valves by Circuit 414.
• Compressed air flows from the compressor, through the compressor air dryer (5346) airlines and spring solenoid valves into the rear springs (5560).
• As the rear springs raise the rear body height, the air suspension height sensor increases in length until the preset trim height is reached.
• The control module then turns off the compressor (through the relay) and closes the air spring solenoid valves.

----------------------------------------------------------------------
Weight Removed When weight is removed:

• The air suspension height sensor (5359) length is increased from the trim length, sending a "rear is high" signal to the control module (5A919).
• The control module then opens the vent solenoid valve (located in the compressor assembly) by switching Circuit 421 to ground and opens the solenoid valves (5311) by switching Circuits 416 and 429 to ground. This restores the rear of the vehicle to trim position.
• Compressed air flows from rear springs (5560), through the air spring solenoid valves, air lines, compressor air dryer (5346), and out the vent solenoid valve.
• As the body lowers, the air suspension height sensor length decreases until the preset trim height is reached.
• The control module then closes the vent and solenoid valves.

-----------------------------------------
Control module operates as follows:

• In general the control module uses a 45-second averaging interval to determine when compress and vent operations are needed.
• However, door courtesy lamp switch (13713) inputs can override the 45-second averaging interval so compress and vent operations can begin immediately, if needed.
• The 45-second averaging interval is used to keep the control module from making unneeded corrections.
• When a vehicle at the correct rear trim height hits a bump, the air suspension height sensor output will read low and high in addition to trim until the oscillations die out.
• If the control module were to correct for these "bump induced readings", system duty cycle would increase unnecessarily.
• The 45-second averaging interval not only eliminates corrections due to bumps, but also eliminates unneeded corrections resulting from braking, accelerating, and turning. The control module tabulates the air suspension height sensor readings, and does not begin a compress or vent operation until the air suspension height sensor (5359) reads low or high for 45 seconds consistently.
• There are more restrictions on vent operations than there are on compress operations.
• To eliminate the chance of catching a door on a curb as the vehicle vents down, the control module will not allow any venting to occur when a door is open.
• The control module does not allow any vent operations for the first 45 seconds after the ignition switch (11572) has been turned to RUN.
  • Even if a vehicle is extremely high in the rear, DO NOT expect it to vent until the ignition switch has been turned to RUN for 45 seconds.

this will get you started. report back on progress and we'll go from there. There is a diagnostic test that will provide codes I think. I will look.

The system consists of unique rear air springs, air compressor, air lines, air spring solenoids, height sensor, air suspension control module, attachments and associated signals derived from both driver and road inputs. With these components and signals, the air suspension control module commands changes in vehicle height that are necessary for the load leveling features.
The load leveling feature rear air suspension (RAS) systems shall automatically make adjustments in vehicle height so that the vehicle is always at trim height and constant front-to-rear vehicle attitudes are maintained over the expected load range of the vehicle. Adjustments in height that are necessary to correct height differences between the vehicle's left and right sides for RAS system shall be restricted to what can be reliably achieved with one air suspension height sensor.
The system uses one air suspension height sensor, a steering sensor, generic electronic module (GEM) transfer case inputs, and other vehicle sensors to measure driver and road inputs. The system changes vehicle height using an air compressor, two air lines, and the use of an air spring with an air spring solenoid.
The air suspension system holds vehicle height when the rear hatch or any door is opened. The system stores rear vehicle height the moment any open door is detected. The system then maintains this height regardless of the addition or removal of a load. The system will return to its commanded height when all doors are closed and the vehicle speed exceeds 16 km/h (10 mph).
Air Suspension Switch
The air suspension switch is located behind the RH kick panel on a mounting bracket. The switch interrupts power to the air suspension control module.
The air suspension switch supplies a signal to the air suspension control module. Without the air suspension control module receiving this signal the load leveling system is inoperative and will not react when rear of the vehicle is raised or lowered. If the air suspension system is disabled by turning off air suspension switch, a "CHECK SUSP" will appear in the RH corner of the instrument cluster with the ignition in the run position.
Air Compressor
The RAS air compressor:

• Is not interchangeable with four wheel air suspension (4WAS) compressor.
• Consists of the compressor and vent solenoid; neither are replaceable as individual items.
• Is mounted in the engine compartment between the washer fluid bottle and headlamp (RH front corner).
• Is a single cylinder electric motor driven unit that provides pressurized air as required.
• Is powered by a solid state relay, controlled by the air suspension control module.
• Passes pressurized air through the compressor air drier that contains silica gel (a drying agent). Moisture is then removed from the compressor air drier when vented air passes out of the system during vent operation.
• Air drier has a single port and is not interchangeable with 4WAS compressor air drier.
• Air drier may be replaced separately.
• Incorporates a snorkle that may be replaced separately.

The vent solenoid:

• Allows air to escape from the system during venting actions.
• Is located in the air compressor cylinder head.
• Has a 160 psi internal relief valve.
• Shares a common electrical connector with the air compressor motor.
• Is enclosed in the cylinder head casting, which forms an integral valve housing that allows the valve tip to enter the pressurized side of the system.
• Has an O-ring seal that prevents air leakage past the valve tip.
• Opens when the air suspension control module determines lowering is required.
• Provides an escape route for pressurized air that opens when system pressures exceed safe operating levels.
• Is replaced with the air compressor as a unit.

Air Spring
RAS vehicles use air springs in the rear. The air springs provide a varying spring rate proportional to the systems air pressure and volume. The air suspension system regulates the air pressure in each air spring by compressing and venting the system air. Increasing air pressure (compressing) raises the rear of the vehicle while decreasing air pressure (venting) lowers the rear of the vehicle. Vehicle height is maintained by the addition and removal of air in each air spring through an air spring solenoid installed in the upper spring cap and energized through the air suspension control module.
The air springs are mounted between the axle spring seats and the frame upper spring seats.
The two air springs replace the conventional rear coil springs.
Air Suspension Height Sensor
When the air suspension height sensor indicates that the rear of the vehicle is lower than trim under normal driving conditions, the air compressor will turn on and pump compressed air to the air springs. When the sensor indicates that the rear of the vehicle is raised above trim under normal driving conditions, this will cause the air to be vented from the air springs to lower the vehicle back to its trim height level.
One air suspension height sensor is mounted on the vehicle. The air suspension height sensor sends a voltage signal to the air suspension control module. The output ranges from approximately 4.75 volts at minimum height (when the vehicle is low or in full jounce), to 0.25 volts at maximum height (when the vehicle is high or in full rebound). The air suspension height sensor has a useable range of 80 mm (3 in) compared to total suspension travel of 200-250 mm (8 to 10 in) at the wheel. Therefore, the air suspension height sensor is mounted to the suspension at a point where full rear suspension travel at the wheel is relative to 80 mm of travel at the air suspension height sensor. The air suspension height sensor is attached between the No. 5 frame crossmember (upper socket) and the panhard rod (lower socket). Replace the air suspension height sensor as a unit.
Compressor Relay
The compressor relay is energized by the air suspension control module to allow high current to flow from the battery to the compressor motor.

• A solid state relay is used in the air suspension system for air compressor control. The relay incorporates a custom power metal oxide semi-conductor field effect transistor (MOSFET) and ceramic hybrid circuitry. The relay switches high current loads in response to low power signals and is controlled by the logic of the air suspension control module.

Air Suspension Control Module
NOTE: The 4WAS air suspension control module is used for the RAS system. The internal processor recognizes external circuitry to determine if it is installed in a 4WAS or a RAS equipped vehicle.
NOTE: The air suspension control module is calibrated with information from the air suspension height sensor. A new or exchanged air suspension control module requires a ride height adjustment calibration process to be performed.
The air suspension control module controls the air compressor motor (through a solid state relay), and the air spring solenoids. The air suspension control module also provides power to the air suspension height sensor. The air suspension control module controls vehicle height adjustments by monitoring the air suspension height sensor, vehicle speed, a steering sensor, acceleration input, the door ajar signal, transfer case signals, and the brake pedal position (BPP) switch. The air suspension control module also conducts all fail-safe and diagnostic strategies and contains self-test and communication software for testing of the vehicle and related components.
The air suspension control module is mounted in the passenger compartment inside the instrument panel above the radio and temperature controls.
The air suspension control module monitors and controls the air suspension system through a 32-pin two-way connector. The air suspension control module is keyed so that the air suspension control module cannot be plugged into an incorrect harness. There are two sides of the harness connection to the air suspension control module. Each is uniquely colored and keyed to prevent reversing the connections.
Solenoid Valve, Air Spring
WARNING: Never rotate an air spring solenoid valve to the release slot in the end cap fitting until all pressurized air has escaped from the spring to prevent damage or injury.
The air spring solenoid:

• allows air to enter and exit the air spring during leveling operations.
• is electrically operated and controlled by the air suspension control module.

Air Suspension Diagnostic Connector
The air suspension diagnostic connector is used to aid the technician in diagnosing the air suspension system. It is also used to vent the system of compressed air when air suspension system components need to be repaired or replaced. The air suspension diagnostic connector is located under steering column.

here's some info. Do you have a warning light on or does it say "Check Susp"?

Control Module
NOTE: The 4-wheel air suspension (4WAS) control module is also used for the rear air suspension (RAS) system. The internal processor recognizes external circuitry to determine if it is installed in a 4WAS or a RAS system.
NOTE: The air suspension control module is calibrated with information from the air suspension height sensors. A new or swapped air suspension control module requires the ride height adjustment calibration process to be performed.
A microcontroller-based electronic air suspension control module controls the air compressor motor (through a solid state relay), and all system solenoids. The air suspension control module also provides power to front and rear height sensors. The air suspension control module controls vehicle height adjustments by monitoring the two height sensors, vehicle speed, a steering sensor, acceleration input, the door ajar signal, transfer case signals, and the brake pedal position (BPP) switch. The air suspension control module also conducts all fail-safe and diagnostic strategies and contains self-test and communication software for testing of the vehicle and related components.
The air suspension control module is mounted in the passenger compartment inside the instrument panel, above the radio and temperature controls. The air suspension control module is interchangeable between the RAS and 4WAS system.
The air suspension control module monitors and controls the system through a 32-pin two-way connector. The air suspension control module is keyed so that it cannot be plugged into an incorrect harness. There are two sides of the harness connection to the air suspension control module. Each is uniquely colored and keyed to prevent reversing the connections.
Solenoid, Air Spring
WARNING: Never rotate an air spring solenoid valve to the release slot in the end cap fitting until all pressurized air has escaped from the spring to prevent damage or injury.
The air spring solenoid:

• Allows air to enter and exit the air spring during leveling operations.
• Is electrically operated and controlled by the air suspension control module.
• Is only replaced as a unit.

Air Suspension Diagnostic Connector
The air suspension diagnostic connector is used to aid the technician in diagnosing the air suspension system. It is also used to vent the system of compressed air when air suspension system components need to be repaired or replaced. The air suspension diagnostic connector is located under the steering column.
Steering Sensor
The steering sensor is mounted inside the passenger compartment on the steering column. It provides steering rate and position to the air suspension control module through two signals.
Pressure Relief Valve
The pressure relief valve (PRV) protects the rear air suspension components by venting the system to a specific pressure in the case of a system malfunction. The system will decrease the pressure to an acceptable level to maintain vehicle height. In the normal operation mode with normal system pressure the PRV is constantly closed and does not have any effect on the system performance or function. The PRV is replaceable without any air lines.
The PRV is located in the rear of the vehicle on the middle of crossmember #5 as a part of the rear air line assembly.

do you have just rear air suspension? here's rear only. 4 wheel different. Deler an run a diagnostic test with WDS machine and get fault codes.
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The air suspension system is designed to improve ride, handling and general vehicle performance for static, on-road and off-road driving conditions:

• Ride is improved by using an air type spring (the soft ride is inherent).
• Handling is improved by maintaining constant vehicle attitude.

The system consists of unique rear air springs, the air compressor, air lines, air spring solenoids, height sensor, air suspension control module, attachments and associated signals derived from both driver and road inputs. With these components and signals, the air suspension control module commands changes in vehicle height that are necessary for the load leveling features.
The load leveling feature rear air suspension (RAS) systems shall automatically make adjustments in vehicle height so that the vehicle is always at trim height and constant front-to-rear vehicle attitudes are maintained over the expected load range of the vehicle. Adjustments in height that are necessary to correct height differences between the vehicle's left and right sides for the RAS system shall be restricted to what can be reliably achieved with one air suspension height sensor.
The system uses one air suspension height sensor, a steering sensor, generic electronic module (GEM) and other vehicle sensors to measure driver and road inputs. The system changes vehicle height using an air compressor, two air lines and the use of air springs with air spring solenoids.
The air suspension system holds vehicle height when the rear hatch or any door is opened. The system stores rear vehicle height the moment any open door is detected. The system then maintains this height regardless of the addition or removal of a load. The system will return to its commanded height when all doors are closed or the vehicle speed exceeds 16 km/h (10 mph).
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Air Suspension Height Sensor
One air suspension height sensor is mounted on the vehicle. The air suspension height sensor sends a voltage signal to the air suspension control module. The output ranges from approximately 4.75 volts at minimum height (when the vehicle is low or in full jounce), to 0.25 volts at maximum height (when the vehicle is high or in full rebound). The air suspension height sensor has a useable range of 80 mm (3.2 in) compared to total suspension travel of 200-250 mm (8 to 10 in) at the wheel. Therefore, the air suspension height sensor is mounted to the suspension at a point where full rear suspension travel at the wheel is relative to 80 mm (3.2 in) of travel at the air suspension height sensor. The air suspension height sensor is attached between the No. 5 frame crossmember (upper socket) and the panhard rod (lower socket).
When the air suspension height sensor indicates that the rear of the vehicle is lower than trim under normal driving conditions, the air compressor will turn on and pump compressed air to the air springs. When the sensor indicates that the rear of the vehicle is raised above trim under normal driving conditions, this will cause the air to be vented from the air springs to lower the vehicle back to its trim height level
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• Uneven vehicle height

• Circuitry.
• Rear pneumatic fault.
• Air compressor assembly.
• Air suspension control module.

• Go To Pinpoint Test I .