C1253

BRAKE CONTROL: ELECTRONICALLY CONTROLLED BRAKE SYSTEM: C1252/52: Brake Booster Pump Motor on Time Abnormally Long





DESCRIPTION

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 relay 1 for Electronically Controlled Brake control, and the motor relay 2 for ABS control.
If either is malfunctioning, the will other substitute.






WIRING DIAGRAM





INSPECTION PROCEDURE
NOTE: When replacing the skid control ECU, perform initialization of linear solenoid valve and calibration Initialization.

PROCEDURE

1. PERFORM ACTIVE TEST BY TECHSTREAM (ABS MOTOR RELAY)
(a) Connect Techstream to the DLC3.
(b) Turn the ignition switch on.
(c) Select the Active Test mode on Techstream.
(d) Check the operating sound of the ABS motor individually when operating it with Techstream.

ABS / VSC / TRAC:





*: Electronically Controlled Brake
OK:
The operating sound of the ABS motor should be heard.
NG -- INSPECT ABS MOTOR RELAY
OK -- Continue to next step.
2. INSPECT FUSE (ABS MTR1 AND ABS MTR2 FUSES)





(a) Remove the ABS MTR1 and ABS MTR2 fuses from R/B No.4.
(b) Measure the resistance according to the value(s) in the table below.
Resistance:






NG -- REPLACE FUSE
OK -- Continue to next step.
3. INSPECT BRAKE ACTUATOR ASSEMBLY





(a) Disconnect the brake actuator assembly connector.
(b) Measure the resistance according to the value(s) in the table below.
Resistance:






NG -- REPLACE BRAKE ACTUATOR ASSEMBLY
OK -- Continue to next step.
4. CHECK HARNESS AND CONNECTOR (BETWEEN SKID CONTROL ECU AND BRAKE ACTUATOR ASSEMBLY)





(a) Disconnect the skid control ECU connector and brake actuator assembly connector.
(b) Measure the resistance according to the value(s) in the table below.
Resistance:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
5. READ VALUE OF TECHSTREAM (ACCUMULATOR PRESSURE SENSOR)
(a) Connect Techstream to the DLC3.
(b) Turn the ignition switch on.
(c) Select the Data List mode on Techstream.

ABS / VSC / TRAC:





(d) Depress the brake pedal 4 or 5 times to operate the pump motor, and check the output value on Techstream with the motor stopped (not braking).
OK:
Accumulator (ACC) pressure sensor voltage does not drop.
NG -- REPLACE BRAKE ACTUATOR ASSEMBLY
OK -- REPLACE SKID CONTROL ECU
6. INSPECT ABS MOTOR RELAY





(a) Remove the ABS MTR1 relay and ABS MTR 2 relay.
(b) Measure the resistance according to the value(s) in the table below.
Resistance:






NG -- REPLACE ABS MOTOR RELAY
OK -- Continue to next step.
7. CHECK HARNESS AND CONNECTOR (BETWEEN R/B NO.4 AND BATTERY)





(a) Remove the ABS MTR1 relay and ABS MTR 2 relay.
(b) Measure the voltage according to the value(s) in the table below.
Voltage:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
8. CHECK HARNESS AND CONNECTOR (BETWEEN R/B NO.4 AND BREAK ACTUATOR ASSEMBLY)





(a) Disconnect the brake actuator assembly connector.
(b) Remove the ABS MTR1 relay and ABS MTR 2 relay.
(c) Measure the resistance according to the value(s) in the table below.
Resistance:





(d) Measure the resistance according to the value(s) in the table below.
Resistance:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
9. CHECK HARNESS AND CONNECTOR (BETWEEN R/B NO.4 AND SKID CONTROL ECU)





(a) Disconnect the skid control ECU connector.
(b) Remove the ABS MTR1 relay and ABS MTR2 relay.
(c) Measure the resistance according to the value(s) in the table below.
Resistance:





(d) Measure the resistance according to the value(s) in the table below.
Resistance:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE SKID CONTROL ECU