DTC C1604-96: ECU Hardware Error: General Description
WARNING: This page is about a different car, the 2021 Kia Seltos. However, it is still accessible from the selected car via links, so may be relevant.
The Hydraulic Electronic Control Unit (HECU) consists of an Electronic Control Unit (ECU) and a Hydraulic Control Unit (HCU).
The HCU portion of the assembly contains a pump motor, solenoid valves, and accumulator. The function of the HCU is to increase, decrease or maintain the hydraulic pressure supplied to a wheel by operating the return pump according to HECU control signal while ABS control is active. The ECU monitors various sensor and switch inputs. These inputs are used to make decisions regarding HCU component operation.