Electronically Controlled Brake System (Ebs) (Diagnostic Codes & Symptom Tests): Overview Lexus GS III facelift

DESCRIPTION

The speed sensor detects wheel speed and sends the appropriate signals to the ECU. These signals are used to control the ABS system. This speed sensor contains a sensor IC, which consists of 2 MREs (Magnetic Resistance Element). The speed sensor rotor, which consists of 48 sets of N and S poles that are arranged in a circle, is integrated with the inner race of the hub bearing.

To detect the rotation direction, the output waves are used to determine the relationship of the pulses that are generated by 2 MREs. Upon receiving this signal, the sensor IC outputs a forward or backward wave to the ECU.

DTCs C1271/71 and C1272/72 can be deleted when the speed sensor sends a vehicle speed signal or the Test Mode ends. DTCs C1271/71 and C1272/72 are output only in the Test Mode.

Scheme 126

HINT

1. DTC C0200/31 is for the right front speed sensor.
2. DTC C0205/32 is for the left front speed sensor.

Scheme 127

Refer to DTC C0200/31 and C0205/32. Refer to DTC C0200/31: Front Speed Sensor RH Circuit; DTC C0205/32: Front Speed Sensor LH Circuit; DTC C1271/71: Low Output Signal of Front Speed Sensor RH (Test Mode DTC); DTC C1272/72: Low Output Signal of Front Speed Sensor LH (Test Mode DTC) .

DTCs C1273/73 and C1274/74 can be deleted when the speed sensor sends a vehicle speed signal or the Test Mode ends. DTCs C1273/73 and C1274/74 are output only in the Test Mode.

HINT

1. DTC C0210/33 is for the right rear speed sensor.
2. DTC C0215/34 is for the left rear speed sensor.

Scheme 128

If a malfunction in the engine control system is detected, the operations of VSC and TRAC are prohibited by the fail-safe function. When the signals from the engine are input normally, the fail-safe is canceled and the DTC is not stored.

When a fluid level drop in the master cylinder reservoir is detected, the signal is input to the skid control ECU.

When the DTC for the fluid level drop is memorized, the warning is canceled and the DTC is not stored if the fluid level returns to normal.

Scheme 129

The circuit is used to send TRAC and VSC control information from the skid control ECU to the ECM, and engine control information from the ECM to the skid control ECU via the CAN communication system.

The skid control ECU receives signals from the yaw rate and acceleration sensor via the CAN communication system.

The yaw rate sensor has the built-in acceleration sensor and detects the vehicle's condition using 2 circuits (GL1, GL2).

If there is trouble in the bus lines between the yaw rate and acceleration sensor and the CAN communication system, the DTCs U0123/62 (yaw rate sensor communication trouble) and U0124/95 (acceleration sensor communication trouble) are output.

The DTCs are also output when the calibration has not been completed.

The steering angle sensor signal is sent to the skid control ECU via the CAN communication system. When there is a malfunction in the CAN communication system, it will be detected by the diagnosis function.

Scheme 130

The skid control ECU receives signals from the yaw rate and acceleration sensor via the CAN communication system.

The yaw rate sensor has a built-in acceleration sensor and detects the vehicle's condition using 2 circuits (GL1, GL2).

If there is trouble in the bus lines between the yaw rate and acceleration sensor and the CAN communication system, the DTC U0123/62 (malfunction in CAN communication with yaw rate sensor) and U0124/95 (malfunction in CAN communication with acceleration sensor) are output.

These DTCs are also output when the calibration has not been completed.

DTCs C0371/71 and C1279/79 can be deleted when the yaw rate and acceleration sensor sends a yaw rate and/or acceleration signal or the Test Mode ends. DTCs C0371/71 and C1279/79 are output only in the Test Mode.

Scheme 131

Refer to DTCs C0200/31 and C0205/32. Refer to DTC C0200/31: Front Speed Sensor RH Circuit; DTC C0205/32: Front Speed Sensor LH Circuit; DTC C1271/71: Low Output Signal of Front Speed Sensor RH (Test Mode DTC); DTC C1272/72: Low Output Signal of Front Speed Sensor LH (Test Mode DTC) .

DTCs C1275/75 to C1278/78 can be deleted when the speed sensor sends a vehicle speed signal or the Test Mode ends. DTCs C1275/75 to C1278/78 are output only in the Test Mode.

HINT

1. DTC C1235/35 is for the right front speed sensor.
2. DTC C1236/36 is for the left front speed sensor.
3. DTC C1238/38 is for the right rear speed sensor.
4. DTC C1239/39 is for the left rear speed sensor.

These codes are memorized when the power source voltage for the skid control ECU drops or the voltage for the ABS MAIN1 relay and ABS MAIN2 relay operation drops.

HINT

DTC C1256/57 (accumulator low pressure) may be memorized if the power source voltage drops.

Scheme 132

Scheme 133

The master cylinder pressure sensor and the wheel cylinder pressure sensor are built into the brake actuator, and measure the master cylinder pressure and the wheel cylinder pressure sent to the skid control ECU.

DTC C1281/81 can be deleted when the master cylinder pressure sensor sends a master cylinder pressure signal or the Test Mode ends. DTC C1281/81 is output only in the Test Mode.

Scheme 134

The stroke sensor inputs the pedal stroke into the skid control ECU.

DTC C1346/71 can be deleted when the brake pedal stroke sensor sends a stroke sensor signal or the Test Mode ends. DTC C1346/71 is output only in the Test Mode.

Scheme 135

The skid control ECU inputs the stop light switch signal and detects braking condition.

The skid control ECU has a circuit for open detection. The skid control ECU outputs the DTC if it detects an open in the stop light signal input line when the stop light switch is off or an open in the stop light circuit (skid control ECU side).

Scheme 136

Scheme 137

The skid control ECU detects decreases in the accumulator pressure according to the data from the accumulator pressure sensor, and then starts and stops the pump motor by operating the motor relay.

The skid control ECU usually drives the motor (ABS MOTOR1) relay 1 for Electronically Controlled Brake System control, and the motor (ABS MOTOR2) relay 2 for ABS control. If either is of them malfunctioning, the other will substitute.

Scheme 138

The accumulator pressure sensor is built into the actuator and detects the accumulator pressure.

The skid control ECU turns on the brake control warning light and sounds the skid control buzzer if it senses a decrease in the accumulator pressure.

The skid control ECU communicates with the steering control (VGRS) ECU via CAN communication.

If a malfunction in the VGRS system is detected, cooperative control of the steering is prohibited by the fail-safe function.

The skid control ECU acquires steering angle sensor zero point every time the engine switch is turned on (IG) and the vehicle is driven at 35 km/h (22 mph) or more for approximately 5 seconds. The ECU also stores the previous zero point.

If front wheel alignment or steering wheel position is adjusted without disconnecting the negative battery terminal, or if yaw rate and acceleration sensor zero point is not acquired after the adjustments have been completed, the skid control ECU detects the difference between the previous zero point and newly acquired zero point and outputs this DTC to indicate a poor adjustment.

Warning of the steering angle sensor zero point malfunction will be canceled by turning the engine switch off.

The skid control ECU outputs this DTC if malfunctions are found in the circuit inside the ECU by self-diagnosis.

The skid control ECU communicates with the power steering (EPS) ECU via CAN communication.

If a malfunction in the electric power steering (EPS) control system is detected, cooperative control of the steering is prohibited by the fail-safe function.

The ABS main relay remains ON for approximately 2 minutes after the engine switch is turned OFF and the input of brake operation signals stops, and supplies power to the system to keep it ready to operate.

Each solenoid adjusts pressure which affects each wheel cylinder according to signals from the skid control ECU and controls the vehicle.

The master cut solenoid (SMC 1/2) is closed and blocks the master cylinder pressure from the Electronically Controlled Brake System control pressure when the system is normal. The master cut solenoid is open and sends the master cylinder fluid pressure to the non-assisted brake wheel cylinders during the fail-safe operation when the system is malfunctioning.

Scheme 139

The stroke simulator solenoid (SCSS) generates pedal reactive effort during Electronically Controlled Brake System control. If one or more of the front wheels loses brake booster function, the simulator operation is prohibited.

Scheme 140

The skid control ECU inputs the operating fluid pressure of each wheel cylinder using the wheel cylinder pressure sensors in order to control the braking force of each wheel.

DTCs may be stored if one of the following occurs

1. Brake fluid leaks.
2. Wheel cylinder vibrates due to uneven wear of brake disc rotor.
3. Foreign matter enters solenoid valve.
4. Line pressure drops during air bleeding.
5. Disc brake pad is replaced.
6. Rotor is replaced.

The skid control ECU stores and corrects the difference in each individual part such as the stroke sensor, actuator solenoids. Perform initialization of linear solenoid valve and calibration if these parts are replaced.

The DTCs are cancelled when the result of linear valve offset learning is normal.

The accumulator pressure sensor is built into the brake actuator.

The skid control ECU detects the accumulator pressure based on the data sent from the accumulator pressure sensor, and then runs and stops the pump motor by operating the motor relay.

DTCs may be output if the accumulator pressure drops due to frequent braking (this is not a malfunction).

The brake control power supply assembly (capacitor) is used as auxiliary power for brake control when battery voltage is low.

Scheme 141

Scheme 142

Scheme 143

Scheme 144

Scheme 145

Scheme 146

1. CHECK FREEZE FRAME DATA Check the information code from the Freeze Frame Data memorized when the DTC (C1377/43) is stored. Refer to «FREEZE FRAME DATA»(ref-382793-S41860830772011012800000) . Result Condition Proceed To Information codes (109, and 110) are output A Information codes (101, 102, 105, 106, 107, and 108) are output B Information code (103) is output C C --> See step 7 B --> REPLACE BRAKE CONTROL POWER SUPPLY A: Go to next step
2. INSPECT FUSE (ABS1 AND ABS MAIN1 FUSES) Remove the ABS1 and ABS MAIN1 fuses from the engine room R/B (J/B) No. 1. Check the ABS1 and ABS MAIN1 fuses. Resistance Below 1 ohms (Continuity) NG --> REPLACE FUSE (ABS1 OR ABS MAIN1 FUSE) OK: Go to next step
3. INSPECT BRAKE CONTROL POWER SUPPLY (+BC AND GND TERMINAL) Disconnect the brake control power supply connector. Measure the voltage according to the value(s) in the table below. Voltage Tester Connection Specified Condition U27-8 (+BC) - Body ground 10 to 14 V Measure the resistance according to the value(s) in the table below. Resistance Tester Connection Specified Condition U27-14 (GND) - Body ground Below 1 ohms NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (+BC OR GND CIRCUIT) OK: Go to next step
4. INSPECT SKID CONTROL ECU (DI TERMINAL) Disconnect the skid control ECU (A13, A15) connectors. Measure the voltage according to the value(s) in the table below. Voltage Tester Connection Specified Condition A13-39 (DI1) - Body ground 10 to 14 V A15-38 (DI2) - Body ground 10 to 14 V NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (DI CIRCUIT) OK: Go to next step
5. INSPECT BRAKE CONTROL POWER SUPPLY (OUT TERMINAL) Measure the voltage according to the value(s) in the table below. HINT: Perform inspection while the brake is not operated. Voltage Tester Connection Specified Condition U27-1 (OUT1) - Body ground 10 to 14 V U27-2 (CTY+) - Body ground 10 to 14 V (*1) U27-7 (OUT2) - Body ground 10 to 14 V (*1): For 5 seconds after the driver's door is opened. OK --> See step 9 NG: Go to next step
6. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU TO BRAKE CONTROL POWER SUPPLY) Disconnect the skid control ECU (A13, A15) connectors and brake control power supply connector. Measure the resistance according to the value(s) in the table below. Resistance Tester Connection Specified Condition A13-13 (CTY+) - U27-2 (CTY+) Below 1 ohms A13-21 (CBI1) - U27-1 (OUT1) Below 1 ohms A15-40 (CBI2) - U27-7 (OUT2) Below 1 ohms Measure the resistance according to the value(s) in the table below. Resistance Tester Connection Specified Condition A13-13 (CTY+) - Body ground 10 kohms or higher A13-21 (CBI1) - Body ground 10 kohms or higher A15-40 (CBI2) - Body ground 10 kohms or higher OK --> See step 9 NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR
7. INSPECT BATTERY Check the battery voltage. Voltage 11 to 14 V NG --> INSPECT CHARGING SYSTEM OK: Go to next step
8. INSPECT BRAKE CONTROL POWER SUPPLY (+BC TERMINAL) Disconnect the brake control power supply connector. Measure the voltage according to the value(s) in the table below. Voltage Tester Connection Specified Condition U27-8 (+BC) - Body ground 10 to 14 V NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (+BC CIRCUIT) OK: Go to next step
9. RECONFIRM DTC Clear the DTC. Refer to «DTC CHECK / CLEAR»(ref-382793-S21584973372011012800000) . Turn the engine switch on (IG). Check if the same DTC is recorded. Refer to «DTC CHECK / CLEAR»(ref-382793-S21584973372011012800000) . HINT: Reinstall the sensors, connectors, etc. and restore the vehicle to its prior condition before rechecking for DTCs. Result Display (DTC Output) Proceed To DTC (C1377/43) is not output A DTC (C1377/43) is output B B --> REPLACE BRAKE CONTROL POWER SUPPLY A --> END

Refer to DTC C1377/43. Refer to DTC C1377/43: Capacitor Malfunction .

The DTC is stored if a brake fluid or internal or other leak is detected due to improper sealing in the actuator. Internal leakage is suspected if the pump motor operates frequently without braking.

The skid control ECU acquires the steering angle sensor zero point every time the engine switch is turned on (IG) and the vehicle is driven at 35 km/h (22 mph) or more for approximately 5 seconds. The ECU also stores previous zero points.

DTCs C1439/66 and C1445/66 will be cleared when the engine switch is turned off.

If the skid control ECU determines that the vehicle is being driven at a steep bank angle, the skid control ECU stores DTC C1440/98 while VSC operation is temporarily disabled.

It is not a malfunction if the system and sensor circuits are normal and if the normal VSC operation resumes, which automatically clears DTC 1440/98, after the vehicle is returned to a normal position.

HINT

DTC C1440/98 and the yaw rate and acceleration sensor DTC are stored when the skid control ECU determines that the vehicle is being driven at a steep bank angle and either of the following conditions is present

1. The yaw rate and acceleration sensor is installed at a titled angle.
2. The yaw rate and acceleration sensor signal output is stuck.

The skid control ECU receives signals from the yaw rate and acceleration sensor via the CAN communication system.

The yaw rate sensor has a built-in acceleration sensor and detects the vehicle condition.

The skid control ECU inputs the signals from the ECM, power steering (EPS) ECU, steering control (VGRS) ECU, steering angle sensor, and yaw rate and acceleration sensor via the CAN communication system.

Scheme 147

The skid control ECU is connected to the combination meter via CAN and multiplex communications.

If any of the following is detected, the ABS warning light remains on.

1. The skid control ECU connectors are disconnected from the skid control ECU.
2. There is a malfunction in the skid control ECU internal circuit.
3. There is an open in the harness between the combination meter and the skid control ECU.

HINT

In some cases, the Techstream cannot be used when the skid control ECU is abnormal.

Scheme 148

The skid control ECU is connected to the combination meter via CAN and multiplex communications.

If any of the following is detected, the BRAKE warning light remains on

1. The skid control ECU connector is disconnected from the skid control ECU.
2. The brake fluid level is insufficient.
3. The parking brake is applied.
4. The EBD is defective.

Scheme 149

The skid control ECU is connected to the combination meter via the CAN and multiplex communication systems.

Pressing the VSC OFF switch turns off traction control and pressing and holding this switch turns off traction and VSC controls. If TRAC control turns off, the TRAC OFF message will be displayed on the multi-information display.

Scheme 150

The skid control ECU is connected to the combination meter via the CAN and multiplex communication systems.

If the ECU stores a DTC, the brake control warning light comes on in the combination meter.

The skid control ECU is connected to the combination meter via CAN and multiplex communications.

Scheme 151

The skid control ECU is connected to the combination meter via the CAN and multiplex communication systems.

Pressing the VSC OFF switch turns off traction control and pressing and holding this switch turns off traction and VSC controls. If VSC control turns off, the VSC OFF indicator light will come on.

Scheme 152

The skid control ECU is connected to the combination meter via the CAN and multiplex communication systems.

The skid control ECU is connected to the combination meter via the CAN and multiplex communication systems.

If the skid control ECU stores a DTC, the SLIP indicator light will come on in the combination meter.

The SLIP indicator blinks during VSC and/or TRAC operation.

When the system fails, the SLIP indicator comes on to warn the driver.

Scheme 153

The skid control buzzer sounds while the accumulator pressure is abnormally low or an abnormality causing low fluid pressure occurs, and then the VSC is activated.

Scheme 154

Connecting terminals TC and CG of the DLC3 causes the ECU to display the DTC by blinking the ABS warning light.

Scheme 155

In the sensor check mode, a malfunction of the speed sensor that cannot be detected when the vehicle is stopped is detected while driving.

Transition to the sensor check mode can be performed by connecting terminals TS and CG of the DLC3 and turning the engine switch from off to on (IG).

Scheme 156