Kia Forte BD Quiz
Brake System

ABS (Anti-Lock Brake System)

In this manual: Brake System
General Information — 8Maintenance — 32Engine Mechanical System — 47Engine Electrical System — 17Emission Control System — 10Engine Control System/Fuel System — 32Clutch System — 11Manual Transmission — 11DCT (Dual Clutch Transmission) System — 16Drive Shaft and Axle — 8Suspension System — 26Steering — 9Restraints — 11Brake System — 27Body (Interior and Exterior) — 119Body Electrical System — 98Heating, Ventilation, and Air Conditioning — 27
6steps
~36min
2/5difficulty
Done 0 of 6

Components and Component Location

Components

1. ABS control module
2. Front wheel speed sensor
3. Rear wheel speed sensor		 4. ABS Warning Lamp
5. EBD/Parking Brake Warning Lamp

Description and Operation

Description

This specification applies to the HCU (Hydraulic Control Unit) and the ECU (Electronic Control Unit). HECU (Hydraulic and Electronic Control Unit)

This specification is intended for the wiring design and installation of the ABS ECU.

This unit has the following functions.

  • Input of the signal from the wheel speed sensors attached to each wheel.

  • Brake force control.

  • Fail-safe function.

  • Self-diagnosis function.

  • Interface with external diagnostic tester.

Installation location: Engine compartment

  • The length of the brake pipe from the master cylinder port to the HECU inlet port must be max. 1 m.

  • The location must not be close to the engine block and not lower than the wheel.

Operation

The ECU shall be activated by switching on the operating voltage (IGN).

After completion of the initialization phase, the ECU shall be ready for operation.

In the operating state, the ECU shall be ready, within the specified limits (voltage and temperature), to process signals provided by the various sensors and to switch according to the control algorithm defined by the software, and to control the hydraulic and electrical actuators.

Wheel Sensor Signal Processing

The ECU shall receive wheel rotational speed signals from four active wheel speed sensors.

The wheel signals are converted into a voltage signal by the signal conditioning circuit after receiving the current signal from the active wheel speed sensors and feeding it to the input of the ECU.

Solenoid Control Valve

When one side of the valve coil is connected to positive voltage, i.e. supplied through the valve relay, and the other side is connected to ground through a semiconductor circuit, the solenoid valve is actuated.

The electrical function of the coils is always monitored by the valve test pulse under normal operating conditions.

Voltage Limits

  • Overvoltage

    When an overvoltage is detected (above 16.8 V), the ECU cuts off the power to the valve relay and disables the system.

    When the voltage returns to the operating range, the system returns to normal condition after the initialization phase.

  • Undervoltage

    In case of undervoltage (below 9.3 V), ABS control is inhibited and the warning lamp shall be illuminated.

    When the voltage returns to the operating range, the warning lamp goes off and the ECU returns to normal operating mode.

Pump Motor Check

The ECU performs a pump motor test at 30 km/h once after the ignition is switched on.

Diagnostic Interface

Malfunctions detected by the ECU are coded in the ECU, stored in EEPROM and read out by the diagnostic equipment when the ignition is switched on.

The diagnostic interface can also be used to test the ECU during production and to actuate the HCU (air bleeding line or brake test line).

Warning Lamp Module

  1. ABS Warning Lamp

    The ABS warning lamp indicates the self-check and fault status of the ABS. The ABS warning lamp shall illuminate:

    • During the initialization phase after IGN ON (constantly for 3 seconds).

    • In case of ABS operation failure during braking.

    • In diagnostic mode.

    • When the ECU connector is disconnected from the ECU.

  2. EBD/Parking Brake Warning Lamp

    The active EBD warning lamp indicates the self-check and fault status of the EBD. However, if the parking brake switch is ON, the EBD warning lamp is always illuminated regardless of EBD function. The EBD warning lamp shall illuminate:

    • During the initialization phase after IGN ON (constantly for 3 seconds).

    • When the parking brake switch is on or the brake fluid level is low.

    • When the EBD function has failed.

    • In diagnostic mode.

    • When the ECU connector is disconnected from the ECU.

ABS Control

  1. Normal Braking without ABS

    Inlet Valve (IV) Outlet Valve (OV) Return Pump
    Operation Open Close OFF

  2. Decrease Mode

    Inlet Valve (IV) Outlet Valve (OV) Return Pump
    Operation Close Open ON (engine speed control)

  3. Hold Mode

    Inlet Valve (IV) Outlet Valve (OV) Return Pump
    Operation Close Close ON (engine speed control)

  4. Increase Mode

    Inlet Valve (IV) Outlet Valve (OV) Return Pump
    Operation Open Close ON (engine speed control)

Test yourself

A quick Kia Forte BD quiz: every answer comes with an explanation and a link to the manual page.