Circuit Operation

The Electronic Level Control (ELC) keeps the rear of the vehicle at a constant height. Whenever weight is added or removed, the ELC height sensor commands the ELC compressor on or the exhaust solenoid energized. These actions will keep the vehicle at a constant height.

An actuator arm is connected between the rear strut ann and the ELC height sensor, which is mounted on the body. As vehicle height changes the sensor detects this motion and either adds air to the rear struts or exhaust air from the rear struts.

Battery voltage is applied to the ELC height sensor, ELC relay and ELC compressor assembly exhaust solenoid and inflator timer-relay at all times. This allows the ELC system to lower the vehicle height when the ignition switch is in "OFF." Whenever the ignition switch is turned to "RUN," battery voltage is applied to terminal D of the ELC height sensor, after an initial delay, the compressor operates for a few seconds to charge the system.

The ELC height sensor delays 17-27 seconds after a change in vehicle height before closing the "Ground" switch (located in the ELC height sensor). This prevents system operation during normal ride motions. In addition, the ELC height sensor limits compressor or exhaust solenoid operation to a maximum of 7 minutes. This time limit is necessary to prevent ELC system operation in case of a severe system leak. Cycling the ignition switch "OFF" and "ON" resets the 7 minute maximum run time.

Raising The Vehicle
When a load is added to the vehicle, the vehicle body moves downward, the actuator arm rotates upward, and the "Compressor Signal" switch closes (located in the ELC height sensor). After a 17-27 second delay the "Ground" switch closes, the ELC relay coil energizes and the relay contacts close. Battery voltage is now applied to the compressor motor and air is pumped into the rear struts. As the struts inflate, the vehicle body moves upward, the actuator arm rotates back to the level position (plus or minus 1 inch) causing the "Compressor Signal" and the "Ground" switches to open, the ELC relay de-energizes and air is no longer pumped into the rear struts.

Lowering The Vehicle
When a load is removed from the vehicle, the vehicle body moves upward, the actuator arm rotates downward, and the "Exhaust Signal" switch closes (located in the ELC height sensor). After a 17-27 second delay, the "Ground" switch closes, the exhaust solenoid is energized and air is released from the rear struts. As the struts deflate, the vehicle body moves downward and the actuator arm rotates back to the level position (plus or minus 1 inch) causing the "Exhaust Signal" and the "Ground" switches to open, the exhaust solenoid is de-energized and air is no longer released from the rear struts.