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 (ABS MOTOR1) relay 1 for electronically controlled brake system control, and the motor (ABS MOTOR2) relay 2 for ABS control. If either is of them malfunctioning, the other will substitute.






WIRING DIAGRAM





INSPECTION PROCEDURE
NOTE: When replacing the skid control ECU or brake actuator, perform initialization of linear solenoid valve and calibration Programming and Relearning.

PROCEDURE

1. INSPECT FUSE (ABS1, ABS2 AND ABS MOTOR FUSES)
(a) Remove the ABS1, ABS2 and ABS MOTOR fuses from the engine room No. 1 relay block (junction block).
(b) Check the ABS1, ABS2 and ABS MOTOR fuses.
Standard resistance:
Below 1 Ohms
NG -- REPLACE FUSE (ABS1, ABS2 OR ABS MOTOR FUSE)
OK -- Continue to next step.
2. INSPECT BRAKE ACTUATOR ASSEMBLY





(a) Disconnect the A16 ECU connector.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:






NG -- REPLACE BRAKE ACTUATOR ASSEMBLY
OK -- Continue to next step.
3. CHECK WIRE HARNESS (SKID CONTROL ECU - BRAKE ACTUATOR)





(a) Disconnect the A13 ECU connector.
(b) Disconnect the A16 actuator connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard resistance:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
4. INSPECT ABS MOTOR RELAY





(a) Remove the ABS MOTOR1 relay and ABS MOTOR2 relay.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:






NG -- REPLACE ABS MOTOR RELAY
OK -- Continue to next step.
5. INSPECT ABS MOTOR RELAY (POWER SOURCE TERMINAL)





(a) Remove the ABS MOTOR1 relay and ABS MOTOR2 relay.
(b) Measure the voltage according to the value(s) in the table below.
Standard voltage:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)
OK -- Continue to next step.
6. CHECK WIRE HARNESS (BRAKE ACTUATOR - ENGINE ROOM NO. 3 RELAY BLOCK)





(a) Disconnect the A16 actuator connector.
(b) Remove the ABS MOTOR1 relay and ABS MOTOR2 relay.
(c) Measure the resistance according to the value(s) in the table below.
Standard resistance:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
7. CHECK WIRE HARNESS (SKID CONTROL ECU - ENGINE ROOM NO. 3 RELAY BLOCK)





(a) Disconnect the A13 and A15 ECU connectors.
(b) Remove the ABS MOTOR1 relay and ABS MOTOR2 relay.
(c) Measure the resistance according to the value(s) in the table below.
Standard resistance:






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

ABS / VSC / TRAC:





(d) Depress the brake pedal 4 or 5 times to operate the pump motor, and check the output value on the Techstream with the motor stopped (not braking).
OK:
Accumulator pressure sensor voltage does not drop.
NG -- REPLACE BRAKE ACTUATOR ASSEMBLY
OK -- Continue to next step.
9. RECONFIRM DTC
(a) Clear the DTC Reading and Clearing Diagnostic Trouble Codes.
(b) Turn the power switch ON (IG).
(c) Check if the same DTCs are recorded Reading and Clearing Diagnostic Trouble Codes.
HINT: Reinstall the sensors, connectors, etc. and restore the vehicle to its prior condition before rechecking for DTCs.

Result





B -- REPLACE SKID CONTROL ECU
A -- END