ABS-ECU




  • By integrating ABS-ECU into the hydraulic unit, no wiring harness for sending drive signal of the solenoid valve and pump motor is required, assuring higher reliability.
  • By incorporating the G-sensor, no sensor harness is required, enhancing the reliability.
  • Self-diagnostic and memory functions are integrated into ABS-ECU. If any malfunction is detected by the self-diagnostic function, ABS-ECU activates a fail-safe function and illuminates the ABS warning lamp and brake warning lamp*.
    note *: The brake warning lamp is used as the EBD control warning lamp.
  • ABS-ECU detects vehicle speed from the signals of the wheel speed sensor and its incorporated G sensor, recognizes the wheel rotation status, estimates the wheel slip condition based on the preprogrammed algorithm, and then controls the solenoid valve in the hydraulic unit so that the wheels do not lock.

ABS fluid pressure control


ABS control cycle


  1. The ABS-ECU calculates the speed and deceleration of each wheel based on the signals from the four wheel speed sensors and the G sensor incorporated in the ABS-ECU, and estimates the vehicle speed at that time.
  2. When the brake pedal is depressed, the brake fluid pressure applied to the wheel cylinder increases, and the wheel speed decreases. When the difference between the wheel speed and vehicle speed increases, and the vehicle deceleration goes below the specified value (Point A), ECU determines that the wheels are about to be locked. At this time, ECU reduces the brake fluid pressure by outputting the pressure decrease signal to the solenoid valves (IN, OUT). (between a and b)
  3. When the vehicle deceleration and wheel speed begin recovery, and the vehicle speed reaches the point B, ECU outputs the pressure hold signal to maintain the wheel cylinder fluid pressure. (between b and c)
  4. When the wheel speed deceleration is further recovered and overpasses the point C, ECU determines that the wheel lock possibility has been eliminated and increases the brake fluid pressure by outputting the pressure increase signal again. (between c and d)
  5. Brake fluid pressure is controlled by repeating the increase and hold of the pressure. (between d and e)
  6. When the wheel deceleration goes below the threshold again, ABS-ECU controls the brake fluid pressure by repeating the cycle (Step 2 to 5).
Four-wheel control
    ABS fluid pressure is controlled independently for four wheels.

EBD fluid pressure control






INITIAL CHECK


*
note *: The ABS warning lamp may stay on after the ignition switch is turned ON until the startup vehicle speed reaches approximately 10 km/h. As far as ABS-ECU memorizes any diagnosis code related to the wheel speed sensor malfunction recorded during the previous ignition ON status, ABS-ECU continues illuminating the ABS warning lamp until it verifies that the malfunction for that code is resolved (startup check).

INITIAL CHECK




STARTUP CHECK




1.*

note *: Initial startup indicates a first startup after the system has started.
2.


CONSTANT CHECK




1.



2.

3.



4.


CAN COMMUNICATION


*
note *: The brake warning lamp is used as EBD control warning lamp.

FAIL-SAFE FUNCTION


*
note *: The brake warning lamp is used as EBD control warning lamp.
Diagnosis code No.
Item
Countermeasures for failure
EBD control
ABS control
Brake warning lamp
ABS warning lamp
C100A
Abnormality in FL wheel speed sensor circuit
Executed (Prohibited when two or more wheels are faulty.)
Prohibited
Extinguished*2
Illuminated*3
C1015
Abnormality in FR wheel speed sensor circuit
C1020
Abnormality in RL wheel speed sensor circuit
C102B
Abnormality in RR wheel speed sensor circuit
C1011
Abnormality in FL wheel speed sensor signal
Executed (Prohibited when two or more wheels are faulty.)
Prohibited
Extinguished*2
Illuminated*3
C101C
Abnormality in FR wheel speed sensor signal
C1027
Abnormality in RL wheel speed sensor signal
C1032
Abnormality in RR wheel speed sensor signal
C1014
Mutual monitoring of FL wheel speed sensor
Executed (Prohibited when two or more wheels are faulty.)
Prohibited
Extinguished*2
Illuminated*3
C101F
Mutual monitoring of FR wheel speed sensor
C102A
Mutual monitoring of RL wheel speed sensor
C1035
Mutual monitoring of RR wheel speed sensor
C1041
Abnormality in periodical signal for FL wheel speed sensor
Executed (Prohibited when two or more wheels are faulty.)
Prohibited
Extinguished*2
Illuminated*3
C1042
Abnormality in periodical signal for FR wheel speed sensor
C1043
Abnormality in periodical signal for RL wheel speed sensor
C1044
Abnormality in periodical signal for RR wheel speed sensor
C1046
FL wheel speed sensor control phase time exceeded
Executed (Prohibited when two or more wheels are faulty.)
Prohibited
Extinguished*2
Illuminated*3
C1047
FR wheel speed sensor control phase time exceeded
C1048
RL wheel speed sensor control phase time exceeded
C1049
RR wheel speed sensor control phase time exceeded
C104B
Abnormality in FL wheel inlet valve system
Prohibited
Prohibited
Illuminates
Illuminates
C104F
Abnormality in FR wheel inlet valve system
C1053
Abnormality in RL wheel inlet valve system
C1057
Abnormality in RR wheel inlet valve system
C105F
Abnormality in FL wheel outlet valve system
Prohibited
Prohibited
Illuminates
Illuminates
C1063
Abnormality in FR wheel outlet valve system
C1067
Abnormality in RL wheel outlet valve system
C105B
Abnormality in RR wheel outlet valve system
C2104
Malfunction of valve power supply circuit
Prohibited
Prohibited
Illuminates
Illuminates
C1073
Malfunction of motor drive circuit
Executed
Prohibited
Extinguished
Illuminated*3
C2116
Abnormality in pump motor power supply voltage
Executed
Prohibited
Extinguished
Illuminated*3
C1000
Abnormality in stop lamp switch circuit
Executed
Executed
Extinguished
Extinguished
C2200
Trouble in ABS-ECU
Prohibited
Prohibited
Illuminates
Illuminates
C2100
Battery voltage problem (low voltage)
9.7 ± 0.3 V or less*1
Executed
Prohibited
Extinguished
Illuminates
8.0 ± 0.5 V or less *1
Prohibited
Prohibited
Illuminates
Illuminates
C2101
Battery voltage problem (high voltage)
18.0 ± 1.0 V or more
Prohibited
Prohibited
Illuminates
Illuminates
C1395
Brake fluid filling not completed
Executed
Executed
Extinguished
Flashes (1 Hz)
C2203
VIN not written
Executed
Executed
Extinguished
Illuminates
C1210
Defective G sensor
Abnormality in output voltage
Executed
Prohibited
Extinguished
Illuminates
C1242
Defective G sensor
Abnormality in output voltage
Executed
Prohibited
Extinguished
Illuminates
C2111
Sensor power supply circuit/Low input
Executed
Prohibited
Extinguished
Illuminates
C2112
Sensor power supply circuit/High input
Executed
Prohibited
Extinguished
Illuminates
C1608
Implausible diagnosis data
Executed
Executed
Extinguished
Extinguished
U0001
Bus off
Executed
Executed
Extinguished
Extinguished
U0100
Engine time-out error
Executed
Executed
Extinguished
Extinguished
U0114
4WD-ECU time-out error
Executed
Executed
Extinguished
Extinguished
U0141
ETACS time-out error
Executed
Executed
Extinguished
Extinguished
U1415
Variant coding not implemented
Executed
Prohibited
Extinguished
Illuminates
U1417
Invalid variant coding value (including wrong assembly)
Executed
Prohibited
Extinguished
Illuminates
note
  • *1 This diagnosis code is not set within the vehicle speed of 20 km/h or less.
  • *2 Turns ON when two or more wheels are faulty.
  • *3 Stays ON until the vehicle speed reaches 10 km/h when the ignition switch is turned to ON next time.

DIAGNOSTIC FUNCTION




  • Diagnosis code set
  • Service data output
  • Actuator test

DIAGNOSIS CODE SET



note
  • *EEPROM (Electrical Erasable & Programmable ROM): Special type of memory that can be programmed or erased electrically
  • For each diagnosis item, refer to Workshop Manual.

SERVICE DATA OUTPUT



note For service data items, refer to Workshop Manual.

ACTUATOR TEST



note
  • When ABS-ECU is disabled, the actuator test cannot be performed.
  • The actuator test can be performed only when the vehicle is stationary. When the vehicle speed reaches 10 km/h, the forcible actuator operation is disabled.
  • During actuator test, the ABS warning lamp flashes in 2Hz, and ABS control is prohibited.
  • After the actuator test has been performed, the brake warning lamp and ABS warning lamp illuminate until the ignition switch is turned to ON again or the communication between M.U.T.-III and ABS-ECU is terminated.
  • For the actuator test specification, refer to Workshop Manual.