Brake Booster Pump Motor on Time Abnormally Long - Electronically Controlled Brake System

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

DTC C1252/52 - Brake Booster Pump Motor on Time Abnormally Long

DTC C1253/53 - Pump Motor Relay Malfunction

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 (ABS MTR) for Electronically Controlled Brake control, and the motor relay 2 (ABS MTR 2) for ABS control. If either is malfunctioning, the other substitutes.






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 USING TECHSTREAM (ABS MOTOR RELAY OPERATION)
(a) Select the Active Test, generate a control command, and then check that the ABS motor relay operates.

ABS / VSC / TRAC:





OK:
The operation sound of the ABS motor should be heard.
NG -- INSPECT RELAY (Marking: ABS MTR, ABS MTR 2)
OK -- Continue to next step.

2. INSPECT FUSE (ABS-1, ABS-2)




(a) Remove the ABS-1 and ABS-2 fuses from the engine room relay block.
(b) Measure the resistance of the fuses.
Standard resistance:
Below 1 Ohms
NG -- REPLACE FUSE
OK -- Continue to next step.

3. INSPECT BRAKE ACTUATOR ASSEMBLY




(a) Disconnect the brake actuator connector.
(b) Measure the resistance of the actuator.
Standard resistance:






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

4. CHECK WIRE HARNESS (SKID CONTROL ECU - BRAKE ACTUATOR ASSEMBLY)




(a) Disconnect the S7 ECU connector.
(b) Disconnect the A2 actuator connector.
(c) Measure the resistance of the wire harness side connectors.
Standard resistance:






NG -- REPAIR OR REPLACE HARNESS AND CONNECTOR
OK -- Continue to next step.

5. READ VALUE USING TECHSTREAM (ACCUMULATOR PRESSURE SENSOR)
(a) Check the Data List for proper functioning of the accumulator pressure sensor.
(b) 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).

ABS / VSC / TRAC:





OK:
Accumulator pressure sensor voltage does not drop.
NG -- REPLACE BRAKE ACTUATOR ASSEMBLY
OK -- REPLACE SKID CONTROL ECU
6. INSPECT RELAY (Marking: ABS MTR, ABS MTR 2)




(a) Remove the ABS MTR and ABS MTR 2 relays from the engine room relay block.
(b) Measure the resistance of the relays.
Standard resistance:






NG -- REPLACE RELAY
OK -- Continue to next step.

7. CHECK WIRE HARNESS (ENGINE ROOM RELAY BLOCK - BATTERY)




(a) Remove the ABS MTR and MTR 2 relays from the engine room relay block.
(b) Measure the voltage of the wire harness side connectors.
Standard voltage:






NG -- REPAIR OR REPLACE HARNESS AND CONNECTOR
OK -- Continue to next step.

8. CHECK WIRE HARNESS (ENGINE ROOM RELAY BLOCK - BRAKE ACTUATOR)




(a) Disconnect the A2 actuator connector.
(b) Remove the ABS MTR and ABS MTR 2 relays from the engine room relay block.
(c) Measure the resistance of the wire harness side connectors.
Standard resistance:






NG -- REPAIR OR REPLACE HARNESS AND CONNECTOR
OK -- Continue to next step.

9. CHECK WIRE HARNESS (ENGINE ROOM RELAY BLOCK - SKID CONTROL ECU)




(a) Disconnect the S7 and S10 ECU connectors.
(b) Remove the ABS MTR and MTR 2 relays from the engine room relay block.
(c) Measure the resistance of the wire harness side connectors.
Standard resistance:






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