Pump Motor Relay Malfunction - Electronically Controlled Brake System

BRAKE CONTROL: ELECTRONICALLY CONTROLLED BRAKE SYSTEM: C1252/52,C1253/53: 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 for Electronically Controlled Brake control, and the motor relay 2 for ABS control. If either of them is malfunctioning, the other will substitute.






WIRING DIAGRAM





INSPECTION PROCEDURE
NOTICE: When replacing the skid control ECU or brake actuator assembly, perform initialization of linear solenoid valve and calibration Initialization.

PROCEDURE

1. INSPECT ABS MTR FUSE




(a) Remove the fusible link from the engine room R/B.




(b) Check if the fusible link is melted.
OK:
The fusible link is not melted.




(c) Install the fusible link to the engine room R/B with the bolt.
Torque: 5.4 Nm (55 kgf-cm, 48in-lbf)
NG -- REPLACE FUSIBLE LINK (ABS MTR FUSE)
OK -- Continue to next step.
2. PERFORM ACTIVE TEST USING TECHSTREAM (ABS MOTOR RELAY)
(a) Connect Techstream to the DLC3.
(b) Turn the power switch on (IG).
(c) Select the Active Test mode on Techstream.

ABS / VSC / TRAC:





*: Electronically Controlled Brake
(d) Check the operation sound of the ABS motor relay and motor when operating it with Techstream.
OK:
The operation sound of the ABS motor relay and motor should be heard.
NG -- INSPECT ABS MOTOR RELAY (ABS MTR1, 2 RELAY)
OK -- Continue to next step.
3. INSPECT BRAKE ACTUATOR ASSEMBLY




(a) Turn the power switch off.
(b) Disconnect the brake actuator connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard resistance:






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




(a) Disconnect the skid control ECU connector.
(b) 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.
5. READ VALUE USING TECHSTREAM (ACCUMULATOR PRESSURE SENSOR)
(a) Reconnect the skid control ECU connector and the brake actuator connector.
(b) Connect Techstream to the DLC3.
(c) Turn the power switch on (IG).
(d) Select the Data List mode on Techstream.

ABS / VSC / TRAC:





(e) 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 pressure sensor voltage does not drop.
NG -- REPLACE BRAKE ACTUATOR ASSEMBLY
OK -- Continue to next step.
6. RECONFIRM DTC
(a) Turn the power switch off.
(b) Clear the DTC Reading and Clearing Diagnostic Trouble Codes.
(c) Turn the power switch on (IG).
(d) Check if the same DTC is recorded Reading and Clearing Diagnostic Trouble Codes.
Result:






B -- REPLACE SKID CONTROL ECU
A -- CHECK FOR INTERMITTENT PROBLEMS (SYMPTOM SIMULATION)
7. INSPECT ABS MOTOR RELAY (ABS MTR1, 2 RELAY)




(a) Turn the power switch off.
(b) Remove the ABS MTR1 relay and the ABS MTR2 relay.
(c) Measure the resistance according to the value(s) in the table below.
Standard resistance:






NG -- REPLACE ABS MOTOR RELAY (ABS MTR1, 2 RELAY)
OK -- Continue to next step.
8. INSPECT ENGINE ROOM NO. 3 RELAY BLOCK (POWER SOURCE TERMINAL)




(a) 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.
9. CHECK HARNESS AND CONNECTOR (BRAKE ACTUATOR - ENGINE ROOM NO. 3 RELAY BLOCK)




(a) Disconnect the brake actuator connector.
(b) 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.
10. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - ENGINE ROOM NO. 3 RELAY BLOCK)




(a) Disconnect the skid control ECU connectors.
(b) 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.
11. RECONFIRM DTC
(a) Clear the DTC Reading and Clearing Diagnostic Trouble Codes.
(b) Turn the power switch on (IG).
(c) Check if the same DTC is recorded Reading and Clearing Diagnostic Trouble Codes.
HINT: Reinstall the relays, connectors, etc. and restore the vehicle to its prior condition before rechecking for DTCs.

Result:






B -- REPLACE SKID CONTROL ECU
A -- CHECK FOR INTERMITTENT PROBLEMS (SYMPTOM SIMULATION)