DTC C1604-04: ECU Hardware Error: General Description

The ESP (ESC) consists of an ECU (Electronic Control Unit) and a HCU (Hydraulic Control Unit). The HCU contains a pump motor, solenoid valves, and accumulator. The HCU increases, decreases, or maintains the hydraulic pressure supplied to a wheel by operating the return pump according to ESP (ESC) control signal when ABS control is active.

The ECU monitors various sensor and switch inputs. These inputs are used to make a decision on how to operate HCU components.