C1252

BRAKE CONTROL: ELECTRONICALLY CONTROLLED BRAKE SYSTEM: C1252/52, C1253/53: Brake Booster Pump Motor on Time Abnormally Long
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 motor relay 1 for electronically controlled brake system control, and motor relay 2 for ABS control. If either of the relays is malfunctioning, the other is used as a substitute.

WIRING DIAGRAM

INSPECTION PROCEDURE

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

PROCEDURE

1. PERFORM ACTIVE TEST USING TECHSTREAM (MOTOR RELAY)

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(c) Select the Active Test on the Techstream Data List / Active Test.

ABS/VSC/TRAC

*: Electronically Controlled Brake System

(d) Check the operation sound of the motor relay and motor when operating the relay using the Techstream.

OK:

The operation sound of the motor relay and motor can be heard.

NG -- INSPECT ABS NO. 1, 2 FUSE
OK -- Continue to next step.

2. INSPECT BRAKE BOOSTER PUMP

(a) Turn the ignition switch off.

(b) Make sure that there is no looseness at the locking part and the connecting part of the connectors.

(c) Disconnect the brake booster pump connectors.

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

Standard Resistance:

Text in Illustration

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

3. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - BRAKE BOOSTER PUMP)

(a) Make sure that there is no looseness at the locking part and the connecting part of the connector.

(b) Disconnect the A46 skid control ECU connector.

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

Standard Resistance:

Text in Illustration

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

4. READ VALUE USING TECHSTREAM (ACCUMULATOR PRESSURE SENSOR)

(a) Reconnect the skid control ECU connector and the brake booster pump connectors.

(b) Connect the Techstream to the DLC3.

(c) Turn the ignition switch to ON.

(d) Select the Data List on the Techstream Data List / Active Test.

ABS/VSC/TRAC

(e) Wait for 30 seconds without operating the brake pedal. Then check the accumulator pressure sensor output value's change is within the specified range.

OK:

Accumulator pressure sensor output value's change is within 0.2 V.

NG -- PERFORM ACTIVE TEST USING TECHSTREAM (SOLENOID VALVE)
OK -- Continue to next step.

5. RECONFIRM DTC

(a) Turn the ignition switch off.

(b) Clear the DTCs Reading and Clearing Diagnostic Trouble Codes.

(c) Turn the ignition switch to ON.

(d) Check if the same DTC is recorded Reading and Clearing Diagnostic Trouble Codes.

Result:

B -- REPLACE SKID CONTROL ECU Removal

A -- CHECK FOR INTERMITTENT PROBLEMS How To Proceed With Troubleshooting

6. INSPECT ABS NO. 1, 2 FUSE

(a) Turn the ignition switch off.

(b) Remove the fusible link block from the engine room relay block.

(c) Check if the fusible link is melted.

OK:

The fusible link is not melted.

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

Standard Resistance:

Text in Illustration

NG -- REPLACE FUSIBLE LINK BLOCK (ABS NO. 1, 2 FUSE)
OK -- Continue to next step.

7. INSPECT ABS MOTOR RELAY (ABS MTR1, 2)

(a) Install the fusible link block to the engine room No. 2 relay block.

(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)
OK -- Continue to next step.

8. INSPECT ENGINE ROOM NO. 2 RELAY BLOCK (POWER SOURCE TERMINAL)

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

Standard Voltage:

Text in Illustration

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)
OK -- Continue to next step.

9. CHECK HARNESS AND CONNECTOR (BRAKE BOOSTER PUMP - ENGINE ROOM NO. 2 RELAY BLOCK)

(a) Make sure that there is no looseness at the locking part and the connecting part of the connectors.

(b) Disconnect the brake booster pump connectors.

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

Standard Resistance:

Text in Illustration

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

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

(a) Make sure that there is no looseness at the locking part and the connecting part of the connectors.

(b) Disconnect the A45 and A46 skid control ECU connectors.

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

Standard Resistance:

Text in Illustration

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE SKID CONTROL ECU Removal

11. PERFORM ACTIVE TEST USING TECHSTREAM (SOLENOID VALVE)

(a) Select the Active Test on the Techstream Data List / Active Test.

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

* Main relays 1 and 2 are on.
* Shift lever is in P.
* Parking brake is applied.
* Vehicle speed is 0 km/h (0 mph).

ABS/VSC/TRAC

*: Electronically Controlled Brake System

(b) Perform the Active Test of the solenoid using the Techstream.

(d) Check that the output value of each wheel cylinder does not increase.

OK:

The output value of each wheel cylinder does not increase.

HINT
If any output value increases, there may be a brake fluid leak in the brake actuator.

NG -- REPLACE BRAKE ACTUATOR ASSEMBLY Removal

OK -- REPLACE BRAKE BOOSTER PUMP Removal