Electronic Suspension Control
| Callout | Component Name |
|---|---|
| B196 | B196 Air Suspension Pressure Sensor |
| Q4 | Q4 Vehicle Level Control Solenoid Valve |
| K19 | K19 Suspension 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 (ALC) system maintains a desired rear suspension position under all types of loading conditions
When the vehicle is unloaded, the rear 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 rear of the vehicle, the position sensor's 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 compressor relay, which activates the compressor causing the air pressure in the air spring to inflate. This inflation raises the rear of 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 air spring 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 air springs. 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 180 seconds to protect the compressor components from thermal damage.
The ESCM has the ability to detect malfunctions within the ALC system. Any malfunctions detected will cause the DIC to display the SERVICE LEVELING SYSTEM message.