Circuit Operation

The Electronic Level Control keeps the rear of the vehicle at a constant height. If weight is added to the vehicle, the ELC height sensor turns on the ELC compressor assembly. Air is pumped into the rear struts until the vehicle is level.

An actuator arm is connected between the rear axle control and the ELC height sensor, which is mounted on the left front side of the rear suspension support assembly. It turns as the vehicle height changes. A solid-state unit detects this motion and operates the ELC compressor assembly to control the air flow into and out of the rear struts.

Voltage is applied at all times to the ELC height sensor, ELC relay and ELC compressor assembly exhaust solenoid. This allows the ELC system to lower or raise the vehicle height even with the ignition switch "OFF." Voltage is applied to ELC height sensor terminal D only with the ignition switch in "RUN." The compressor, after an initial delay, runs for a few seconds to charge the system when the ignition switch is turned to "RUN."

The ELC height sensor delays ELC compressor assembly operation for 17-27 seconds after a change in height. This prevents system operation during normal ride motions. In addition, the ELC height sensor limits compressor run time or exhaust solenoid energized time to a maximum of 7 minutes.
This time limit is necessary to prevent continuous compressor operation in case of a severe system leak or continuous exhaust solenoid operation. Turning the ignition switch "OFF" and "ON" resets the 7 minutes.

Raising The Vehicle
When a load is added to the vehicle, the vehicle body is moved downward and the actuator arm rotates upward. After a 17-27 second delay, the coil in the ELC relay is energized and the relay contacts close. Battery voltage is applied to the compressor motor. The compressor operates and pumps air into the adjustable rear struts. As the struts inflate, the vehicle body moves upward. When the actuator arm rotates back, to its original position (plus or minus 1 inch), the relay is no longer energized and the compressor stops.

Lowering The Vehicle
When a load is removed from the vehicle, the vehicle body is moved upward and the actuator arm rotates downward. After a 17-27 second delay, the exhaust solenoid is energized and air is exhausted from the rear struts. As the vehicle body moves downward, the actuator arm is rotated back to its original position (plus or minus 1 inch), the exhaust solenoid is no longer energized.