System Description

• Corrects sinkage of vehicle rear that occurs in laden or towing conditions.
• Maintains vehicle height at a constant level and improves riding comfort by charging or discharging air in air chamber of rear shock absorber, according to signal from vehicle height sensor installed to rear suspension.

System Diagram 

Courtesy of NISSAN NORTH AMERICA, INC.

System Description 

• Based on the signal from the vehicle height sensor, the air levelizer control module operates the air compressor (exhaust solenoid) and controls vehicle height so that it remains at a constant height. This operation occurs if vehicle height of vehicle rear is judged to be 15 mm (0.59 in) or more or 15 mm (0.59 in) or less than standard vehicle height, continuously for 30 seconds, when engine is started.
• The air levelizer control module performs system check of electrical circuit for 15 seconds after engine started. Then the system starts control by the signal from the vehicle height sensor.
• If the vehicle height is within 15 mm (0.59 in) from the standard vehicle height, the vehicle height is not adjusted.
• While driving, it is possible the vehicle height is higher or lower than standard vehicle height 15 mm (0.59 in) for less than 30 seconds. In such situation, the vehicle height will not be adjusted.
• The system is not the complete airtight holding structure, so if the vehicle is not moved for a long time, the vehicle rear body may be to lower. But it is normal.
• If malfunction is detected, the system enters fail-safe mode. Refer to Fail-safe .

INPUT/OUTPUT SIGNAL 

Air levelizer control module transmits and receives following signals between each control unit via CAN communication line.

Component parts	Control signal
ECM	Transmits the following signal via CAN communication line to air levelizer control module. Engine speed signal
Combination meter	Receives the following signal via CAN communication line from air levelizer control module. CK SUSP indicator lamp signal
ABS actuator and electric unit (control unit)	Transmits the following signal via CAN communication line to air levelizer control module. Vehicle speed signal

OPERATING PRINCIPLE 

System Time Table 

Courtesy of NISSAN NORTH AMERICA, INC.

Vehicle height raises [When starting engine, if vehicle height of vehicle rear continues for 30 seconds or more in a status that is 15 mm (0.59 in) or less than standard vehicle height] 

1. Vehicle height sensor detects vehicle height status, and transmits this information to air levelizer control module.
2. Air levelizer control module turns air compressor relay ON and operates air compressor.
3. Air compressor charges air in air chamber of shock absorber.
4. Vehicle height raises, and control is complete when status is -1 mm (-0.04 in) of standard vehicle height value.

Vehicle height lowers [When starting engine, if vehicle height of vehicle rear continues for 30 seconds or more in a status that is 15 mm (0.59 in) or more of standard vehicle height] 

1. Vehicle height sensor detects vehicle height status, and transmits this information to air levelizer control module.
2. Air levelizer control module turns exhaust solenoid of air compressor ON.
3. Air compressor discharges air from air chamber of shock absorber.
4. Vehicle height lowers, and control is complete when status is +1 mm (+0.04 in) of standard vehicle height.