Electronically controlled external damper reservoir

An electronically controller external damper reservoir assembly (eRESI) can be connected to a passive damper and/or substituted for an existing external reservoir to provide semi-active damping control. The eRESI includes a reservoir and a variable base valve assembly actuated by an actuator. A controller is in communication with the actuator and a sensor providing input signal indicative of vehicle movement and is programmed to generate a damping control signal to the actuator based on the input signal, to dynamically control the damping force outputted by a passive damper hydraulically connected to the eRESI. A P/T sensor can be installed to a gas chamber of a vehicle damper to generate a P/T signal indicative of the pressure and temperature of the gas. The controller is programmed to determine a damper position of the damper based on the P/T signal.