Electronically Controlled Brake (Diagnostic Codes & Symptom Tests): Overview Lexus HS I

DESCRIPTION

These DTCs are stored if the VSC and/or electronically controlled brake system detects a malfunction in the ABS control system.

These DTCs are stored if the ABS and/or VSC system detects a malfunction in the electronically controlled brake system.

The speed sensor detects wheel speed and sends the appropriate signals to the skid control ECU. These signals are used for ABS control.

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

Scheme 46

HINT

1. DTCs C0200/31 and C1271/71 are for the front speed sensor RH.
2. DTCs C0205/32 and C1272/72 are for the front speed sensor LH.

Scheme 47

The speed sensor detects wheel speed and sends the appropriate signals to the skid control ECU. These signals are used for ABS control.

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

Scheme 48

HINT

1. DTCs C0210/33 and C1273/73 are for the rear speed sensor RH.
2. DTCs C0215/34 and C1274/74 are for the rear speed sensor LH.

Scheme 49

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 are any problems in the bus lines between the yaw rate and acceleration sensor and the CAN communication system, DTCs U0123/62 (Lost Communication with Yaw Rate Sensor Module) and U0124/95 (Lost Communication with Lateral Acceleration Sensor Module) are output.

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

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

Scheme 50

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

If the DTC for the fluid level drop is memorized, the warning will be canceled and the DTC will not be stored when the fluid level returns to normal.

Scheme 51

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

Identification information sent from other ECUs is stored when shipped from the factory and used as default values.

Note. DTC C1203/95 is output when an incorrect ECU is installed. If initialization is performed and learning occurs with an incorrect ECU installed, operations and functions will differ from that stored when the vehicle was shipped from the factory. Therefore, make sure that learning occurs properly.

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 are any problems in the bus lines between the yaw rate and acceleration sensor and the CAN communication system, DTCs U0123/62 (Lost Communication with Yaw Rate Sensor Module) and U0124/95 (Lost Communication with Lateral Acceleration Sensor Module) will be output.

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

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 is closed and blocks the regulator 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 and regulator hydraulic pressure to the non-assisted brake wheel cylinders during the fail-safe due to a system malfunction.

HINT

If the supply voltage decreases, a drop in current may cause a DTC to be stored.

The skid control ECU controls braking force according to the hybrid control system regenerative braking force and inputs the hydraulic pressure necessary for operating each wheel cylinder according to the wheel cylinder pressure sensor.

DTCs may be stored if one of the following occurs

1. Brake fluid leaks.
2. Wheel cylinder vibrates due to uneven wear of a brake disc.
3. Foreign matter enters solenoid valve.
4. Line pressure drops during air bleeding.
5. Brake pad is replaced.
6. Rotor is replaced. HINT: When replacing the brake pad, retracting the brake calipers piston and attaching a new brake pad will greatly increase the clearance between the brake pad and brake disc, which will likely cause these DTCs to be set the next time the brake pedal is depressed. As there is not malfunction, clear the DTCs.

The skid control ECU inputs steering angle sensor signals via the CAN communication system. When a malfunction occurs in the communication line with the steering angle sensor, DTC U0126/63 (Lost Communication with Steering Angle Sensor Module) is output.

Scheme 52

When foreign matter adheres to the speed sensor tip or speed sensor rotor, these DTCs are output. An abnormal waveform input from the sensor determines these conditions.

These DTCs may be detected when a malfunction occurs in the connector terminals or wire harness of the speed sensor circuit.

DTCs C1275/75 to C1278/78 will be cleared when the speed sensor sends a wheel speed signal or when Test Mode ends. DTCs from C1275/75 to C1278/78 are output only in Test Mode.

HINT

1. DTCs C1235/35 and C1275/75 are for the front speed sensor RH.
2. DTCs C1236/36 and C1276/76 are for the front speed sensor LH.
3. DTCs C1238/38 and C1277/77 are for the rear speed sensor RH.
4. DTCs C1239/39 and C1278/78 are for the rear speed sensor LH.

If a malfunction is detected in the power supply circuit, the skid control ECU power source voltage drops, or there is insufficient voltage to operate the ABS main relay, the skid control ECU will store these DTCs.

These DTCs may also be stored if the auxiliary battery voltage drops below 9.5 V.

HINT

DTC C1256/56 (Accumulator Low Pressure) may also be memorized if there is a drop in power source voltage.

Scheme 53

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

DTC C1281/81 will be cleared when the regulator pressure sensor sends a regulator pressure signal or when Test Mode ends. DTC C1281/81 is output only in Test Mode.

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

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

Scheme 54

The skid control ECU inputs the stop light switch signal and detects the brake pedal operation status.

The skid control ECU has an open detection circuit, which outputs this DTC if it detects an open in the stop light input line or ground line of the stop light circuit with the stop light switch off (brake pedal not depressed).

Scheme 55

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.

Scheme 56

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

The skid control ECU turns on the brake warning light / red (malfunction) and brake warning light / yellow (minor malfunction), and sounds the skid control buzzer if it senses a decrease in the accumulator pressure.

DTC C1256/56 may be output if the accumulator pressure drops due to frequent braking (this is not a malfunction).

The skid control ECU detects a drop in accumulator pressure according to the signals from the accumulator pressure sensor, then operates and stops the motor relay as well as the pump motor.

The skid control ECU troubleshoots the built-in motor relay drive circuit, and outputs this DTC when a malfunction is detected.

The skid control ECU communicates with the hybrid vehicle control ECU and controls braking force according to the motor's regenerative force.

The skid control ECU sends Enhanced-VSC signals to the hybrid vehicle control ECU and inputs operating signals from the hybrid vehicle control ECU.

The skid control ECU uses CAN communication for communication with the hybrid vehicle control ECU. If a communication malfunction is memorized, the skid control ECU prohibits Enhanced-VSC operation and a part of electronically controlled brake system control by fail-safe function.

If the signals from the hybrid vehicle control ECU returned to normal, the warning light will go off and the DTCs C1259/58 and C1310/51 will be cleared.

HINT

These DTCs will be output from the skid control ECU when the hybrid vehicle control ECU sends a malfunction signal to the skid control ECU.

The skid control ECU acquires the steering angle sensor zero point every time the power switch is turned on (READY) 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 the front wheel alignment or the steering wheel position is adjusted without disconnecting the cable from 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.

The warning of the steering angle sensor zero point malfunction will be cancelled by turning the power switch off.

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

The ABS main relay supplies power to the changeover solenoid and the linear solenoid.

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

The skid control ECU stores and corrects the individual differences in the stroke sensor, actuator solenoids, and stroke simulator solenoid. Perform initialization and calibration of the linear solenoid valve if any of these parts is replaced.

The skid control ECU receives the park (P) signal from the hybrid vehicle control ECU through the CAN communication system.

The DTCs are cleared when the linear valve offset learning results are normal.

The accumulator pressure sensor is built into the brake actuator.

The skid control ECU detects the accumulator pressure from the data sent from the accumulator pressure sensor, and then starts 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).

Upon receiving the dynamic radar cruise control system operating signal from the skid control ECU, the relay contact turns on and the stop light comes on.

The DTC is stored if internal or external brake fluid leaks are detected due to improper sealing in the brake actuator or brake booster pump. Internal leaks are suspected if the pump motor operates frequently without braking.

The skid control ECU acquires the steering angle sensor zero point every time the power 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 power 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.

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.

If air bleeding has not been performed, the skid control ECU stores DTC C1451/72 to prevent the entry of air due to the pump motor operation.

DTC C1451/72 is stored when Invalid Mode is selected, the system will not return to normal until air bleeding procedure is performed.

The skid control ECU receives the signals from the hybrid vehicle control ECU, steering angle sensor, and yaw rate and acceleration sensor via the CAN communication system.

Scheme 57

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

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

1. The skid control ECU connector is 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.
4. The ABS control system is defective.

HINT

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

Scheme 58

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

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

If any of the following is detected, the brake warning light / red (malfunction) 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. EBD operation has been disabled.

Scheme 59

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

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

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

Scheme 60

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

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

If the skid control ECU stores a DTC, the brake warning light / yellow (minor malfunction) comes on in the combination meter.

Scheme 61

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

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

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

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

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

If the skid control ECU stores a DTC, the slip indicator light comes on in the combination meter.

The slip indicator light blinks during VSC and/or TRAC operation.

When the system fails, the slip indicator light comes on to warn the driver. Refer to DIAGNOSIS SYSTEM .

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

The skid control buzzer sounds intermittently to warn the driver when the accumulator pressure is abnormally low. This buzzer also sounds intermittently when VSC is operating.

HINT

The skid control buzzer may sound when the accumulator pressure drops due to frequent braking. Refer to DTC C1256/56: Accumulator Low Pressure .

Scheme 62

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

Scheme 63

HINT

When the warning lights continue to blink, a ground short in the wiring of terminal TC of the DLC3 or an internal ground short in one or more ECUs is suspected.

In Test Mode (signal check), a malfunction in a speed sensor that cannot be detected when the vehicle is stopped can be detected while driving.

Sensor check mode can be entered by connecting terminals TS and CG of the DLC3 and turning the power switch from off to on (IG).

Scheme 64

See also:
• REMOVAL
• ADJUSTMENT