Hyundai Tucson Quiz
Braking System

Description and Operation

In this manual: Braking System
General Information — 17Engine Mechanical System — 51Engine Electrical System — 26Emission Control System — 23Engine/Fuel Control System — 44Clutch System — 12MANUAL TRANSMISSION SYSTEM — 12AUTOMATIC TRANSMISSION SYSTEM — 42Four-Wheel Drive (4WD) System — 14Drive Shaft and Axle — 22Suspension System — 30Steering System — 16Restraint — 21Braking System — 47Body Work (Interior and Exterior) — 145Body Electrical System — 162Heating, Ventilation and Air Conditioning — 39
6steps
~36min
2/5difficulty
Done 0 of 6

Description

These specifications apply to the HCU (Hydraulic Control Unit) and ECU (Electronic Control Unit) of the HECU (Hydraulic and Electronic Control Unit). These specifications apply to the wiring design and installation of the ABS/ESP/ECU. This unit has the following functions.
  • Input signals from the pressure sensor, steering wheel angle sensor, lateral acceleration and yaw rate sensor, and wheel speed sensors attached to each wheel.
  • Brake force / driving force / yaw moment control
  • Fail-Safe Function
  • Self-check function
  • Interface with external diagnostic tool
Installation location: Engine compartment
  • The maximum length of the brake line between the master cylinder and the HECU inlet must be 1 meter.
  • The position must not be close to the engine block and not lower than the wheel.
Operation: This ECU operates within the full operating voltage range (ALL). After the initialization phase, the ECU is ready for operation. Under operating conditions, the ECU is ready within the specification limits (voltage and temperature) to process signals from the various sensors and switches. The control algorithm is determined by the software and is used to control the hydraulic and electrical actuators.
Wheel sensor signal processing: The ECU receives the wheel speed signal from the four active wheel sensors. The wheel signals are converted into a voltage signal by the signal processing circuit. The signal processing circuit receives the current signal from the active wheel sensors and provides it as input to the MCU.
Solenoid valve control: When one side of the valve coil is connected to positive voltage through the valve relay and the other side is connected to ground through a solid-state circuit, the solenoid valve operates. The electrical function of the valve coils is always checked by a test pulse under normal operating conditions.
Voltage limits
  • Surge: When an overvoltage is detected (above 17 ± 0.5 V), the ECU switches off the valve relay and interrupts system operation. When the voltage returns to the operating range, the system returns to normal after the initialization phase.
  • Undervoltage: When a reduced voltage is detected (below 9.5 ± 0.5 V), ABS control is disabled and the warning lamp illuminates. When the voltage returns to the operating range, the warning lamp goes off and the ECU returns to normal operation.
Pump motor control: The ECU performs a check of the single-speed pump motor after the ignition is switched off.
Diagnostic interface: Faults detected by the ECU are coded in the ECU and stored in EEPROM memory, and are read by the diagnostic equipment (Hi-Scan Pro) when the ignition switch is in the ON position. The diagnostic interface can also be used to check the ECU during production and to allow use of the HCU on factory test lines (purge line or roller brake tester line).
WARNING LAMP MODULE
  1. ABS WARNING LAMP MODULE: The ABS warning lamp indicates the self-check and the ABS fault status. The ABS warning lamp illuminates:
    • During the initialization phase after ALL ON (continuously for 3 seconds).
    • When ABS functions related to a fault are deactivated.
    • In diagnostic mode.
    • When the ECU connector is disconnected from the ECU.
    • The instrument cluster indicator illuminates when communication with the CAN module is not possible.
  2. EBD / PARK warning lamp module: The active EBD warning lamp module indicates the self-check and the EBD fault status. However, if the parking brake switch is activated, the EBD warning lamp will illuminate regardless of EBD operation. The EBD warning lamp illuminates when:
    • During the initialization phase after ALL ON (continuously for 3 seconds).
    • When the parking brake switch is on or when the brake fluid level is low.
    • When the EBD function is faulty.
    • In diagnostic mode.
    • When the ECU connector is disconnected from the ECU.
    • The instrument cluster indicator illuminates when communication with the CAN module is not possible.

ABS CONTROL

  1. NORMAL BRAKING WITHOUT ABS: During normal braking, voltage is not applied to the solenoid valve, the inlet valve is open, and the outlet valve is closed. When the brake is applied, brake fluid is supplied to the wheel cylinder through the solenoid valve to activate the brake. When the brake is released, brake fluid returns to the master cylinder through the inlet valve and the regulating valve.
    Solenoid valve STATUS Valve Communication PUMP
    Motor
    Inlet valve (NO) OFF Open Master cylinder ⇔ Wheel cylinder OFF
    Outlet valve (NC) OFF Closed Wheel cylinder ⇔ Reservoir

  2. DUMP MODE: In an emergency braking situation, if the wheels begin to lock, the HECU sends a signal to the solenoid valve to reduce brake fluid pressure. Voltage is then supplied to each solenoid. At this point, the inlet valve closes and brake fluid is blocked from the master cylinder. The outlet valve opens and brake fluid flows from the wheel cylinder to the reservoir, causing the pressure to drop.
    SOLENOID VALVE STATUS Valve Communication PUMP
    Motor
    Inlet valve (NO) WE Closed Master cylinder ⇔ Wheel cylinder WE
    Outlet valve (NC) WE Open Wheel cylinder ⇔ Reservoir

  3. HOLD MODE: When the brake fluid pressure reaches the minimum level in the wheel cylinder, the HECU sends a signal to the solenoid valve to maintain a constant pressure. The inlet valve is energized (as opposed to the outlet valve). The inlet and outlet valves then close, and brake fluid is held at the current level inside the wheel cylinder.
    SOLENOID VALVE STATUS Valve Communication PUMP
    Motor
    Inlet valve (NO) WE Closed Master cylinder ⇔ Wheel cylinder OFF
    Outlet valve (NC) OFF Closed Wheel cylinder ⇔ Reservoir

  4. INCREASE MODE: If the HECU determines that the wheels are not locked, it cuts the voltage supply to the solenoid valve. Voltage is not supplied to each solenoid valve, and brake fluid flows into the wheel cylinder through the inlet valve, which increases the pressure.
    SOLENOID VALVE STATUS Valve Communication PUMP
    Motor
    Inlet valve (NO) OFF Open Master cylinder ⇔ Wheel cylinder WE
    Outlet valve (NC) OFF Closed Wheel cylinder ⇔ Reservoir

ABS HECU EXTERNAL CIRCUIT / HYDRAULIC SYSTEM CIRCUIT

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