Automatic Level Control
| Callout | Component Name |
|---|---|
| B196 | B196 Air Suspension Pressure Sensor |
| Q4 | Q4 Vehicle Level Control Solenoid Valve |
| K38 | K38 Chassis Control Module |
| G3 | G3 Air Suspension Compressor |
| B152RR | B152RR Suspension Position Sensor - Right Rear |
| B152LR | B152LR Suspension Position Sensor - Left Rear |
The automatic level control system maintains a desired rear suspension position under all types of towing and loading conditions.
The system uses the chassis control module, automatic level control relay, compressor assembly, air lines, LR and RR shock absorbers with integral air chambers, suspension position sensors, air pressure sensor, vehicle level control solenoid valve, driver information center, and the serial data circuit to perform the system functions.
The system is activated when the ignition key is turned to ON/RUN and will automatically adjust vehicle height thereafter. The system may exhaust (lower vehicle height) for up to 10 minutes after the ignition key has been turned off. When the vehicle is unloaded the rear suspension is at a desired position, which is monitored by the chassis control module using its LR and RR suspension position sensor signal voltage inputs. As weight is added to the rear of the vehicle the position sensor's signal voltage inputs increase. If the chassis control module detects a steady substantial change in position sensor signal voltage, it responds by commanding on the automatic level control relay, which activates the compressor causing the air pressure in both rear shock absorber chambers to inflate. This inflation raises the rear of the vehicle to regain the desired suspension position. When weight is removed, the chassis control module responds by commanding on the exhaust valve to release air from the system causing the air pressure in the shock absorber chambers to deflate. This deflation lowers the rear of 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. The chassis control module also limits the amount of compressor run time to protect the compressor components from thermal damage.
The chassis control module has the ability to detect malfunctions within the automatic level control system. Any malfunctions detected will cause the driver information center to display the SERVICE LEVELING SYSTEM message.