Hyundai Accent (HC): Brake System (ABS/ESC) / ABS(Anti-Lock Brake System)

Hyundai Accent (HC) (2017 - 2022) Service Manual / Brake System (ABS/ESC) / ABS(Anti-Lock Brake System)

Contents:

Description and Operation

- Description This specification applies to HCU (Hydraulic Control Unit) and ECU (Electronic Control Unit) of the HECU. (Hydraulic and Electronic Control Unit)This specification is for the wiring design and installation of ABS ECU.This unit has the functions as follows.

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

– Control of braking force.

– Failsafe function.

– Self diagnosis function.

– Interface with the external diagnosis tester.

Installation Position : Engine Compartment

– Brake tube length from Master cylinder port to HECU inlet port should be max. 1m

– The position should not be close to the engine block and not lower than the wheel.

Operation The ECU shall be put into operation by switching on the operating voltage (IGN).On completion of the initialization phase, the ECU shall be ready for operation.In the operating condition, the ECU shall be ready, within the specified limits (voltage and temperature), to process the signals offered by the various sensors and switches in accordance with the control algorithm defined by the software and to control the hydraulic and electrical actuators.Wheel Sensor Signal Processing The ECU shall receive wheel speed signal from the four active wheel sensors.The wheel signals are converted to voltage signal by the signal conditioning circuit after receiving current signal from active wheel sensors and given as input to the MCU.Solenoid Valve Control When one side of the valve coil is connected to the positive voltage that is provided through the valve relay and the other side is connected to the ground by the semiconductor circuit, the solenoid valve goes into operation.The electrical function of the coils are always monitored by the valve test pulse under normal operation conditions.Voltage Limits

– OvervoltageWhen overvoltage is detected(above 16.8 V), the ECU switches off the valve relay and shuts down the system.When voltage is returned to operating range, the system goes back to the normal condition after the initialization phase.

– UndervoltageIn the event of undervoltage(below 9.3 V), ABS control shall be inhibited and the warning lamp shall be turned on.When voltage is returned to operating range, the warning lamp is switched off and ECU returns to normal operating mode.

Pump Motor Checking The ECU performs a pump motor test at a speed of 30km/h once after IGN is switched on.Diagnostic Interface Failures detected by the ECU are encoded on the ECU, stored in a EEPROM and read out by diagnostic equipment when the ignition switch is turned on.The diagnosis interface can also be used for testing the ECU during production of the ECU and for actuating the HCU (Air-bleeding line or Roll and Brake Test line).Warning Lamp Module [Super Vision]

[General]

1.ABS Warning LampThe active ABS warning lamp indicates the selftest and failure status of the ABS. The ABS warning lamp shall be on :

– During the initialization phase after IGN ON. (continuously 3 seconds).

– In the event of inhibition of ABS functions by failure.

– During diagnostic mode.

– When the ECU Connector is separated from ECU.

2.EBD/Parking brake Warning LampThe active EBD warning lamp indicates the selftest and failure status of the EBD. However, in case the Parking Brake Switch is turned on, the EBD warning lamp is always turned on regardless of EBD functions.The EBD warning lamp shall be on:

– During the initialization phase after IGN ON. (continuously 3 seconds).

– When the Parking Brake Switch is ON or brake fluid level is low.

– When the EBD function is out of order.

– During diagnostic mode.

– When the ECU Connector is separated from ECU.

- ABS Control

1.Normal Braking without ABS

Inlet valve (IV)Outlet valve (OV)Return pump
OperationOpenCloseOFF

   

• IV : Inlet Valve

• OV : Outlet Valve

• RL : Rear left wheel

• FR : Front right wheel

• FL : Front left wheel

• RR : Rear right wheel

• RP : Return pump

2.Decrease Mode

Inlet valve (IV)Outlet valve (OV)Return pump
OperationCloseOpenON (Motor speed control)

   

• IV : Inlet Valve

• OV : Outlet Valve

• RL : Rear left wheel

• FR : Front right wheel

• FL : Front left wheel

• RR : Rear right wheel

• RP : Return pump

3.Hold Mode

Inlet valve (IV)Outlet valve (OV)Return pump
OperationCloseCloseON (Motor speed control)

   

• IV : Inlet Valve

• OV : Outlet Valve

• RL : Rear left wheel

• FR : Front right wheel

• FL : Front left wheel

• RR : Rear right wheel

• RP : Return pump

4.Increase Mode

Inlet valve (IV)Outlet valve (OV)Return pump
OperationOpenCloseON (Motor speed control)

   

• IV : Inlet Valve

• OV : Outlet Valve

• RL : Rear left wheel

• FR : Front right wheel

• FL : Front left wheel

• RR : Rear right wheel

• RP : Return pump

Components and Components Location

- Components

1. ABS Control Module (HECU)
2. Front Wheel Speed Sensor
3. Rear Wheel Speed Sensor
4. ABS Warning lamp
5. EBD / Parking brake warning lamp


Schematic Diagrams

- Schematic Diagrams

- Termianal function

Wire NoDesignationCurrent
maxmin
13Ground for recirculation pump39A10A
1Voltage supply for pump motor39A10A
25Voltage supply for solenoid valves15A2A
38Ground for solenoid valves and ECU15A2A
22Signal wheel speed sensor FL16.8 mA5.9 mA
33Voltage supply for the active wheel speed sensor RL16.8 mA5.9 mA
19Voltage supply for the active wheel speed sensor RR16.8 mA5.9 mA
18Voltage supply for the active wheel speed sensor FR16.8 mA5.9 mA
6Signal wheel speed sensor FR16.8 mA5.9 mA
14CAN LOW30 mA20 mA
34Voltage supply for the active wheel speed sensor FL16.8 mA5.9 mA
20Signal wheel speed sensor RL16.8 mA5.9 mA
32Voltage for HECU1A500 mA
31Signal wheel speed sensor RR16.8 mA5.9 mA
30Brake light switch 10 mA5 mA
26CAN HIGH30 mA20 mA
27Wheel speed sensor outputOpen Draim

Repair procedures

- Inspection ABS System Bleeding This procedure should be followed to ensure adequate bleeding of air and filling of the ESC unit, brake lines and master cylinder with brake fluid.

1.Remove the reservoir cap and fill the brake reservoir with brake fluid.

   

• If there is any brake fluid on any painted surface, wash it off immediately.

• When pressure bleeding, do not depress the brake pedal.

• Recommended fluid........ DOT3 or DOT4

2.Connect a clear plastic tube to the wheel cylinder bleeder plug and insert the other end of the tube into a half filled clear plastic bottle.

3.Connect the GDS to the data link connector located underneath the dash panel.

4.Select and operate according to the instructions on the GDS screen

   

• You must obey the maximum operating time of the ESC motor with the GDS to prevent the motor pump from burning.

1)Select vehicle name.

2) Select ABS/ESC system.

3)Select HCU air bleeding mode.

5.Pump the brake pedal several times, and then loosen the bleeder screw until fluid starts to run out without bubbles. Then close the bleeder screw (A).[Front]

[Rear Disc Brake]

[Rear Durm Brake]

6.Repeat the procedure for wheel in the sequence shown below until air bubbles no longer appear in the fluid.

7.Refill the master cylinder reservoir to MAX (upper) level line.

Troubleshooting ➤

ABS Control Module

- Components

1. Front - right tube
2. Rear - left tube
3. Rear - right tube
4. Front - left tube
5. MC SEC
6. MC PRI
7. ABS control module (HECU)
8. Bracket


- Removal

1.Turn the ignition switch OFF and then disconnect the negative (-) battery cable.

2.Pull up the lock of the HECU connector, then disconnect the connector.

3.Remove the brake fluid from the master cylinder reservoir with a syringe.

   

• Be sure to completely remove foreign substances from around brake fluid reservoir and cap before opening the reservoir cap. If not, it may cause contamination of brake fluid and deterioration in braking performance.

• Do not spill brake fluid on the vehicle, it may damage the paint; if brake fluid does contact the paint, wash it off immediately with water.

4.Disconnect the brake tubes from the HECU by unlocking the nuts counterclockwise with a spanner.

Tightening torque : 13.7 - 16.7 N.m (1.4 - 1.7 kgf.m, 10.1 - 12.3 lb-ft)

5.Loosen the HECU bracket bolts (A), then remove HECU and bracket.

Tightening torque :16.7 - 25.5 N.m (1.7 - 2.6 kgf.m, 12.3 - 18.8 lb-ft)

6.Remove the 3 bolts, then remove the bracket from HECU.

Tightening torque :7.8 - 9.8 N.m (0.8 - 1.0 kgf.m, 5.8 - 7.2 lb-ft)

- Installation

1.To install, reverse the removal procedure.

2.Tighten the HECU mounting bolts and nuts to the specified torque.

3.After installation, bleed the brake system. (Refer to ABS System - "ABS System Bleeding")

Front Wheel Speed Sensor

- Components

1. Front wheel speed sensor
2. Front wheel speed sensor cable


- Removal

1.Loosen the wheel nuts slightly.Raise the vehicle, and make sure it is securely supported.

2.Remove the front wheel and tire (A) from the front hub.

Tightening torque :107.9 - 127.5 N.m (11.0 - 13.0 kgf.m, 79.6 - 94.0 lb-ft)

   

• Be careful not to damage the hub bolts when removing the front wheel and tire.

3.Loosen the mounting holt and then remove the wheel speed sensor cable from the strut assembly.

Tightening torque :7.8 - 11.8 N.m (0.8 - 1.2 kgf.m, 5.8 - 8.7 lb-ft)

4.Remove the wheel speed sensor cable braket bolt (A).

Tightening torque : 7.8 - 11.8 N.m (0.8 - 1.2 kgf.m, 5.8 - 8.7 lb-ft)

5.Loosen the bolt and then remove the wheel speed sensor (A).

Tightening torque :7.8 - 11.8 N.m (0.8 - 1.2 kgf.m, 5.8 - 8.7 lb-ft)

6.Remove the front wheel guard.(Refer to Body - "Front Wheel Guard")

7.Disconnect the wheel speed sensor connector (A) and then remove it.

8.To install, reverse the removal procedure.

- Inspection

1.Measure the output voltage between the terminal of the wheel speed sensor and the body ground.

   

• In order to protect the wheel speed sensor, when measuring output voltage, a 100Ω resister must be used as shown.

2.Compare the change of the output voltage of the wheel speed sensor to the normal change of the output voltage as shown below.

V_low : 0.59V - 0.84VV_high : 1.18V - 1.68VFrequency range : 1 - 2,500 Hz

Rear Wheel Speed Sensor

- Components

[Drum Type]

1. Front wheel speed sensor
2. Front wheel speed sensor cable


[Disc Type]

1. Front wheel speed sensor
2. Front wheel speed sensor cable


- Removal [Disc Type]

1.Loosen the wheel nuts slightly.Raise the vehicle, and make sure it is securely supported.

2.Remove the rear wheel and tire (A) from front hub.

Tightening torque :107.9 - 127.5 N.m (11.0 - 13.0 kgf.m, 79.6 - 94.0 lb-ft)

   

• Be careful not to damage the hub bolts when removing the rear wheel and tire.

3.Disconnect the rear wheel speed sensor connector.

4.Loosen the screws and then remove the brake disc.

Tightening torque :4.9 - 5.9 N.m (0.5 - 0.6 kgf.m, 3.6 - 4.3 lb-ft)

5.Loosen the bolts and then remove the hub bearing.

Tightening torque :49.0 - 58.8 N.m (5.0 - 6.0 kgf.m, 36.2 - 43.4 lb-ft)

6.To install, reverse the removal procedure.

[Drum Type]

1.Loosen the wheel nuts slightly.Raise the vehicle, and make sure it is securely supported.

2.Remove the rear wheel and tire (A) from front hub.

Tightening torque :107.9 - 127.5 N.m (11.0 - 13.0 kgf.m, 79.6 - 94.0 lb-ft)

   

• Be careful not to damage the hub bolts when removing the rear wheel and tire.

3.Loosen the screw and then remove the drum.

Tightening torque :4.9 - 5.9 N.m (0.5 - 0.6 kgf.m, 3.6 - 4.3 lb-ft)

4.Disconnect the rear wheel speed sensor connector.

5.Loosen the hub mounting bolts (A) and then remove the hub from the torsion beam.

Tightening torque :44.1 - 53.9 N.m (4.5 - 5.5 kgf.m, 32.9 - 39.8 lb-ft)

6.To install, reverse the removal procedure.

- Inspection

1.Measure the output voltage between the terminal of the wheel speed sensor and the body ground.

   

• In order to protect the wheel speed sensor, when measuring output voltage, a 100Ω resister must be used as shown.

2.Compare the change of the output voltage of the wheel speed sensor to the normal change of the output voltage as shown below.

V_low : 0.59V - 0.84VV_high : 1.18V - 1.68VFrequency range : 1 - 2,500 Hz

Parking Brake System

Troubleshooting

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