PRECAUTION [ELECTRONICALLY CONTROLLED BRAKE SYSTEM]

id040309070100

1.  Even when the system is normal, the ABS warning light, brake system warning light, TCS/DSC operation indicator light, and the TCS OFF indicator light may turn on depending on the driving conditions and servicing content.

Turning on/flashing warning light	Turn on/flash possibility	Lights off condition	Control status
•  ABS warning light •  Brake system warning light •  TCS/DSC operation indicator light	Only the front wheels are rotated due to the vehicle being jacked up, stuck, or on a chassis dynamometer under the following conditions: •  Detected 8 times for a continuous 10 s while at a vehicle speed of 20 km/h {12 mph} or more (One detection period is when main power is switched from ON (READY off or on) to OFF)	After switching the main power OFF once, the main power is switched ON (READY on) again, the vehicle is driven at 10 km/h {6.2 mph} or more, and then the normal operation is verified.	•  ABS control: Control disabled •  EBD control: Control disabled ―  Control disabled •  Wheel speed sensor malfunction in two wheels or more is detected ―  Control maintained •  Wheel speed sensors in three wheels or more are normal •  TCS control: Control disabled •  DSC control: Control disabled
	Vehicle is driven with parking brake not fully released
	Brake drag
	Sudden acceleration/deceleration
	Left/right or front/back tires which differ (size, air pressure, and wear condition other than those indicated on tire label) are installed
	Lead-acid battery (electrically controlled brake unit power supply terminal voltage) is approx. 9.1 V or less	Lead-acid battery is approx. 9.1 V or more	•  ABS control: Control disabled •  EBD control: Control maintained •  TCS control: Control disabled •  DSC control: Control disabled
Brake system warning light	Brake fluid level is low	Brake fluid level is specified value or more	•  ABS control: Control maintained •  EBD control: Control maintained •  TCS control: Control maintained •  DSC control: Control maintained
Brake system warning light and brake control system warning light			•  ABS control: Control disabled •  EBD control: Control disabled •  TCS control: Control disabled •  DSC control: Control disabled

2.  The electronically controlled brake system consists of electrical and mechanical parts. Therefore, it is necessary to classify the malfunction diagnosis into electrical systems and hydraulic systems.

(1)  Electrical system malfunction

•  The control module has a diagnostic (on-board diagnostic) function which, if an electrical system malfunction occurs, the ABS warning light, brake warning light, TCS/DSC operation indicator light, or TCS OFF indicator light is turned on according to the malfunction conditions. In addition, it keeps a record of previous and occurring malfunctions in the control module, and malfunctions which do not recur when the warning/indicator light turns on can be searched with this function. The recorded malfunction content can be displayed by connecting the M-MDS. The search for the cause of the system malfunction should proceed based on the on-board diagnostic results.

•  If a malfunction symptom occurred in the past but the system is now normal, the cause is most likely a temporary poor contact in the wiring harness. The control module usually operates normally, therefore carefully determine the cause.

•  When servicing is completed, it is necessary to clear any previous DTCs stored in the control module. Be careful not to forget. In addition, if an electronically controlled brake system related part is replaced, verify that a DTC is not displayed when servicing is completed.

•  The ABS warning light may not turn off even if the main power is switched ON (READY off or on) after repairs related to the electrically controlled brake system such as the ABS wheel-speed sensor are completed. In this case, drive the vehicle at a vehicle speed of 10 km/h {6.2 mph} or more and after verifying that the ABS warning light has turned off (troubleshooting completed), clear the DTC.

•  Be careful during servicing, if the main power is switched ON (READY off or on) with the electronically controlled brake system related connector disconnected, an open circuit is determined and a malfunction is recorded.

Caution

•  After replacing the electronically controlled brake unit (brake fluid pressure sensor) or Sophisticated Airbag Sensor (SAS) control module (yaw rate sensor, lateral acceleration speed sensor, longitudinal acceleration speed sensor), perform the sensor initialization procedure for the electronically controlled brake system related parts.

•  Disconnect each CM connector to protect the electronically controlled brake unit and switch the main power OFF to connect.

(2)  Hydraulic system malfunction

•  Malfunctions in a hydraulic system are similar to malfunctions with normal brakes. However, it is necessary to determine whether the malfunction is for an electronically controlled brake system related part or a normal brake part.

•  The hydraulic unit contains precision mechanical parts that could cause damage in the machine if dirt or foreign matter enters it, causing the electronically controlled brake system to not operate. In addition, if the normal brakes are operational but the electronically controlled brake system are not operational, if may be difficult to determine the malfunction location. Therefore, when servicing the electronically controlled brake system, such as brake fluid replacement and pipe removal/installation, be careful of foreign matter penetration.

3.  Abnormal noise when vehicle accelerates from standstill

•  After switching the main power ON (READY on), abnormal noise may be heard from the motor room when the vehicle accelerates from a standstill for the first time. This is the operation sound from the electronically controlled brake system initial check.

•  If there is a complaint from a customer regarding this sound, explain to the customer that the sound is from the initial check necessary to protect the electronically controlled brake system operation and that it is not a malfunction.