21 sty 2008 17:13
Optimum driving safety now has a name : ESP, the Electronic Stability Program.
ESP recognizes critical driving conditions, such as panic reactions in dangerous situations, and stabilizes the vehicle by wheel-individual braking and engine control intervention with no needfor actuating the brake or the gas pedal.
ESP adds a further function known as Active Yaw Control (AYC) to the ABS, TCS, EBD and ESP 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.
ESP 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 ESP 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 ESP CONTROL
ESP 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/ESP 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 ESP calculations. Variant code programming should be performed whenever an HECU is replaced.
PROCEDURE OF VARIANT CODING
1. Install a PCM(ECM & TCM)/ESP normally.
2. Connect the scan tool to the data link connector located underneath the dash panel.
3. Select vehicle name.
4. Select ANTI-LOCK BRAKE SYSTEM.
5. Select the variant coding.
6. Follow the next procedure according to the comment .
7. Confirm the condition , and then push the "REST".
8. If the procedure is finished, the screen is displayed as shown below.
9. IGN off.
10. IGN on.
11. The variant coding is completed.
1) If the warning lamp(ESP, EBD, ABS) is illuminated, follow the "Variant coding" again.
2) For the vehicle equipped 4WD, delete the DTC(s) memorized in 4WD ECU when variant coading is completed.
INPUT AND OUTPUT DIAGRAM
ESP OPERATION MODE
1. STEP 1
The ESP analyzes the intention of the driver.
2. STEP 2
It analyzes the movement of the ESP vehicle.
3. STEP 3
he HECU calculates the required strategy, then actuates the appropriate valves and sents torque control requests via CAN to maintain vehicle stability.
ESP OPERATION MODE1. ESP 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. ESP 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. ESP 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 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
4. ESP 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 shall be on:
1) During the initialization phase after IGN ON. (continuously 3 seconds).
2) In the event of inhibition of ABS functions by failure.
3) During diagnostic mode.
4) When the ECU Connector is seperated 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:
1) During the initialization phase after IGN ON. (continuously 3 seconds).
2) When the Parking Brake Switch is ON or brake fluid level is low.
3) When the EBD function is out of order .
4) During diagnostic mode.
5) When the ECU Connector is seperated from ECU.
ESP Warning Lamp (ESP system)
The ESP warning lamp indicates the self-test and failure status of the ESP.
The ESP warning lamp is turned on under the following conditions :
1) During the initialization phase after IGN ON. (continuously 3 seconds).
2) In the event of inhibition of ESP functions by failure.
3) When driver turn off the ESP function by on/off switch.
4) During diagnostic mode.
ESP Function Lamp (ESP system)
The ESP function lamp indicates the self-test and operating status of the ESP.
The ESP Function lamp operates under the following conditions :
1) During the initialization phase after IGN ON. (continuously 3 seconds).
2) When the ESP control is operating. (Blinking - 2Hz)
ESP On/Off Switch (ESP system)
The ESP On/Off Switch shall be used to toggle the ESP 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 ESP function is on and the switch is used to request an ESC status change.
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