Hyundai Elantra: Description and Operation - ESC(Electronic Stability Control) System - Brake System - Hyundai Elantra HD 2006Ц2010 Service ManualHyundai Elantra: Description and Operation


Description of ESC

Optimum driving safety now has a name : ESC, the Electronic Stability Control.
ESC recognizes critical driving conditions, such as emergency reactions in dangerous situations, and stabilizes the vehicle by wheel-individual braking and engine control intervention.
ESC adds a further function known as Active Yaw Control (AYC) to the ABS, TCS, EBD and ESC functions. Whereas the ABS/TCS function controls wheel slip during braking and acceleration and, thus, mainly intervenes in the longitudinal dynamics of the vehicle, active yaw control stabilizes the vehicle about its vertical axis.
This is achieved by wheel individual brake intervention and adaptation of the momentary engine torque with no need for any action to be taken by the driver.
ESC essentially consists of three assemblies : the sensors, the electronic control unit and the actuators.
Of course, the stability control feature works under all driving and operating conditions. Under certain driving conditions, the ABS/TCS function can be activated simultaneously with the ESC function in response to a command by the driver.
In the event of a failure of the stability control function, the basic safety function, ABS, is still maintained.

Description of ESC Control
ESC system includes ABS/EBD, TCS and AYC (Active yaw control) function.
ABS/EBD function : The ECU changes the active sensor signal (current shift) coming from the four wheel sensors to the square waveform.By using the input of above signals, the ECU calculates the vehicle speed and the acceleration & deceleration of the four wheels.And, the ECU judges whether the ABS/EBD should be actuated or not.
TCS function prevents the wheel slip of drive direction by adding the brake pressure and engine torque reduction via CAN communication.TCS function uses the wheel speed sensor signal to determine the wheel slip as far as ABS function.
AYC function prevents unstable maneuver of the vehicle. To determine the vehicle maneuver, AYC function uses the maneuver sensor signals(Yaw Rate Sensor, Lateral Acceleration Sensor, Steering Wheel Angle Sensor).If vehicle maneuver is unstable (Over Steer or Under Steer), AYC function applies the brake pressure on certain wheel, and send engine torque reduction signal by CAN.
After the key-on, the ECU continually diagnoses the system failure. (self-diagnosis)If the system failure is detected, the ECU informs driver of the system failure through the BRAKE/ABS/ESC warning lamp. (fail-safe warning)

Variant Coding
The HECU is programmed with a variant code based on the vehicle powertrain configuration. This variant code is used to determine the appropriate ESC calculations. Variant code programming should be performed whenever an HECU is replaced.

Procedure Of Variant Coding
1.
Connect the scan tool to the data link connector located underneath the dash panel.
2.
Select vehicle name.
3.
Select ANTI-LOCK BRAKE SYSTEM.
4.
Select the variant coding.

5.
Follow the next procedure according to the comment .

6.
Confirm the condition , and then push the "REST".

7.
If the procedure is finished, the screen is displayed as shown below.

8.
IGN off.
9.
IGN on.
10.
The variant coding is completed.
Х
If the warning lamp(ESC, EBD, ABS) is illuminated, follow the "Variant coding" again.
Х
For the vehicle equipped 4WD, delete the DTC(s) memorized in 4WD ECU when variant coading is completed.
Input and Output Diagram


ESC Operation Mode

1.
Step 1
The ESC analyzes the intention of the driver.

2.
Step 2
It analyzes the movement of the ESC vehicle.

3.
Step 3
The HECU calculates the required strategy, then actuates the appropriate valves and sends torque control requests via CAN to maintain vehicle stability.
ESC Operation Mode
1.
ESC Non-operation-Normal braking.

Inlet valve(EV)
Outlet valve(AV)
Pilot valve(USV)
High pressure switch valve(HSV)
Pump motor
Normal braking
Open
Close
Open
Close
OFF

EV : Inlet Valve
AV : Outlet Valve
LR : Rear left wheel
RF : Front right wheel
LF : Front left wheel
RR : Rear right wheel
PE : Pump motor
USV : Pilot Valve
HSV : High pressure Switch Valve
2.
ESC Increase Mode

Inlet valve(EV)
Outlet valve(AV)
Pilot valve(USV)
High pressure switch valve(HSV)
Pump motor
Normal braking
Open
Close
Close(Partial)
Open
ON(Motor speed control)

EV : Inlet Valve
AV : Outlet Valve
LR : Rear left wheel
RF : Front right wheel
LF : Front left wheel
RR : Rear right wheel
PE : Pump motor
USV : Pilot Valve
HSV : High pressure Switch Valve
3.
ESC Hold Mode ( FR is only controlled.)

Inlet valve(EV)
Outlet valve(AV)
Pilot valve(USV)
High pressure switch valve(HSV)
Pump motor
Normal braking
Close
Close
Close(Partial)
Open
OFF

EV : Inlet Valve
AV : Outlet Valve
LR : Rear left wheel
RF : Front right wheel
LF : Front left wheel
RR : Rear right wheel
PE : Pump motor
USV : Pilot Valve
HSV : High pressure Switch Valve
4.
ESC Decrease Mode (FR is only controlled)

Inlet valve(EV)
Outlet valve(AV)
Pilot valve(USV)
High pressure switch valve(HSV)
Pump motor
Normal braking
Close
Open
Close(Partial)
Open
ON(Motor speed low control)

EV : Inlet Valve
AV : Outlet Valve
LR : Rear left wheel
RF : Front right wheel
LF : Front left wheel
RR : Rear right wheel
PE : Pump motor
USV : Pilot Valve
HSV : High pressure Switch Valve

ABS Warning Lamp module
The active ABS warning lamp module indicates the self-test and failure status of the ABS .The ABS warning lamp may 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.
EBD/Parking Brake Warning Lamp Module
The active EBD warning lamp module indicates the self-test 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.
ESC Warning Lamp (ESC system)
The ESC warning lamp indicates the self-test and failure status of the ESC.
The ESC warning lamp may be turned on under the following conditions :
-
During the initialization phase after IGN ON. (continuously 3 seconds).
-
In the event of inhibition of ESC functions by failure.
-
When driver turn off the ESC function by on/off switch.
-
During diagnostic mode.
ESC Function Lamp (ESC system)
The ESC function lamp indicates the self-test and operating status of the ESC.
The ESC Function lamp operates under the following conditions :
-
During the initialization phase after IGN ON. (continuously 3 seconds).
-
When the ESC control is operating. (Blinking - 2Hz)
ESC On/Off Switch (ESC system)
The ESC On/Off Switch shall be used to toggle the ESC function between On/Off states based upon driver input.
The On/Off switch shall be a normally open, momentary contact switch.
Initial status of the ESC function is on and the switch is used to request an ESC status change.