C1252

BRAKE CONTROL: ELECTRONICALLY CONTROLLED BRAKE SYSTEM: C1252/52,C1253/53: 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 ABS motor relay (ABS MTR1) for electronically controlled brake system control, and the ABS motor relay (ABS MTR2) for ABS control. If either is of them malfunctioning, the other will substitute.





WIRING DIAGRAM





INSPECTION PROCEDURE

NOTICE:
- When replacing the skid control ECU, perform the following operations:
* Initialization of linear solenoid valve and calibration Initialization
* Yaw rate and acceleration sensor zero point calibration Calibration
- When replacing the brake actuator, perform initialization of the linear solenoid valve and calibration Initialization.

PROCEDURE

1. INSPECT FUSE (ABS MTR1, ABS MTR2, ABS MAIN1 AND ABS MAIN2)

(a) Remove the ABS MTR1, ABS MTR2, ABS MAIN1 and ABS MAIN2 fuses from the engine room No. 2 junction block.





(b) Measure the resistance of the fuses.

Standard resistance:





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

2. PERFORM ACTIVE TEST USING TECHSTREAM (ABS MTR1 RELAY)

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch ON (IG).

(c) Select the Active Test mode on the Techstream.

HINT
- The ABS motor relay (ABS MTR1) is a semiconductor relay. It does not emit operation sounds.
- The ABS motor relay (ABS MTR1) cannot be removed and inspected, as it is part of the engine room No. 2 relay block.

ABS/VSC/TRAC:





(d) Remove the terminal cover.





(e) Measure the voltage according to the value(s) in the table below.





Standard voltage:





NG -- CHECK TERMINAL VOLTAGE (IG, BAT)
OK -- Continue to next step.

3. CHECK HARNESS AND CONNECTOR (BRAKE ACCUMULATOR PUMP - ENGINE ROOM NO. 2 JUNCTION BLOCK)

(a) Disconnect the A23 pump connector.

(b) Read value of Techstream (ABS MTR relay).

(1) Connect the Techstream to the DLC3.

(2) Turn the power switch ON (IG).

(3) Select the Active Test mode on the Techstream.

ABS/VSC/TRAC:





(c) Measure the voltage according to the value(s) in the table below.





Standard voltage:





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

4. READ VALUE USING TECHSTREAM (ABS MTR2 RELAY)

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch ON (IG).

(c) Select the Active Test mode on the Techstream.

ABS/VSC/TRAC:





(d) Check the operation sound of the ABS motor relay (ABS MTR2) and motor when operating it with the Techstream.

OK:

The operation sound of the ABS motor relay (ABS MTR2) and motor are heard.

NG -- INSPECT ABS MOTOR RELAY (ABS MTR2)
OK -- Continue to next step.

5. INSPECT BRAKE ACCUMULATOR PUMP

(a) Turn the power switch OFF.





(b) Disconnect the A23 and A24 pump connectors.

(c) Measure the resistance according to the value(s) in the table below.

Standard resistance:





NG -- REPLACE BRAKE ACCUMULATOR PUMP Removal
OK -- Continue to next step.

6. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - BRAKE ACCUMULATOR PUMP)

(a) Turn the power switch OFF.

(b) Disconnect the A19 ECU connector.

(c) Disconnect the A23 and A24 pump connectors.

(d) 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. 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) for 30 seconds.

OK:

The accumulator pressure sensor voltage change is within 0.2 V.

HINT
- This inspection is performed to determine if there is a long term power malfunction when low pressure is detected in the accumulator due to a sensor malfunction, fluid leak in the actuator, or accumulator deterioration.
- If the reservoir fluid level drops, there may be a fluid leak.

NG -- PERFORM ACTIVE TEST USING TECHSTREAM (SMC1, SMC2, SLRRR, AND SLRRL)
OK -- Continue to next step.

8. CHECK TERMINAL VOLTAGE (IG, BAT)





(a) Disconnect the 2F junction block connector.

(b) Measure the voltage according to the value(s) in the table below.

Standard voltage:





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

9. INSPECT ENGINE ROOM NO. 2 JUNCTION BLOCK (INNER CIRCUIT)





(a) Turn the power switch OFF.

(b) Disconnect the 2B and 2F junction block connectors.

(c) Measure the resistance according to the value(s) in the table below.

Standard resistance:





NG -- REPLACE ENGINE ROOM NO. 2 JUNCTION BLOCK AND/OR NO. 2 RELAY BLOCK Locations
OK -- Continue to next step.

10. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - ENGINE ROOM NO. 2 JUNCTION BLOCK)

(a) Turn the power switch OFF.

(b) Disconnect the A19 ECU connector.

(c) Disconnect the 2G junction block connector.

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

Standard resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE ENGINE ROOM NO. 2 JUNCTION BLOCK Locations

11. INSPECT ABS MOTOR RELAY (ABS MTR2)

(a) Remove the ABS motor relay (ABS MTR2).





(b) Measure the resistance according to the value(s) in the table below.

Standard resistance:





NG -- REPLACE ABS MOTOR RELAY (ABS MTR2) Locations
OK -- Continue to next step.

12. CHECK TERMINAL VOLTAGE (NO. 3 RELAY BLOCK)

(a) Remove the ABS motor relay (ABS MTR2).





(b) Measure the voltage according to the value(s) in the table below.

Standard voltage:





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

13. CHECK HARNESS AND CONNECTOR (BRAKE ACCUMULATOR PUMP - NO. 3 RELAY BLOCK)

(a) Disconnect the A24 pump connector.

(b) Remove the ABS motor relay (ABS MTR2).

(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.

14. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - NO. 3 RELAY BLOCK)

(a) Disconnect the A21 ECU connector.

(b) Remove the ABS motor relay (ABS MTR2).

(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.

15. 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 Removal

A -- USE SIMULATION METHOD TO CHECK How To Proceed With Troubleshooting

16. PERFORM ACTIVE TEST USING TECHSTREAM (SMC1, SMC2, SLRRR, AND SLRRL)

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch ON (IG).

(c) Select the Active Test mode on the Techstream.

HINT
The Active Test can be performed when the following conditions are met.

- Main relay 1 and 2 are on.
- Shift lever is P position.
- Parking brake is on.
- Vehicle speed is 0 km/h (0 mph).

ABS/VSC/TRAC:





(d) Using the Techstream, turn SMC1, SMC2, SLRRR, or SLRRL ON.





(e) Check that each wheel cylinder's output value does not increase.

OK:

Each wheel cylinder's output value does not increase.

HINT
If any of wheel cylinder's output value increases, there may be a brake fluid leak in the brake actuator.

NG -- REPLACE BRAKE ACTUATOR Removal

OK -- REPLACE BRAKE ACCUMULATOR PUMP Removal