Toyota Tacoma manuals

Toyota Tacoma 2015-2018 Service Manual: Brake Booster Pump Motor on Time Abnormally Long (C1252)

DESCRIPTION

The motor relay (semiconductor relay) is built into the master cylinder solenoid and drives the pump motor based on a signal from the skid control ECU (master cylinder solenoid).

DTC No.

DTC Detecting Condition

Trouble Areas

C1252

Motor operates for 5 minutes or more.

  • Hydraulic brake booster pump motor
  • Hydraulic brake booster pump motor circuit
  • Accumulator pressure

WIRING DIAGRAM

CAUTION / NOTICE / HINT

CAUTION / NOTICE / HINT

HINT:

When C1253, C1254 or C1256 is output together with C1252, inspect and repair the trouble areas indicated by C1253, C1254 or C1256 first.

PROCEDURE

1.

CHECK HYDRAULIC BRAKE BOOSTER PUMP MOTOR OPERATION

(a) Turn the ignition switch to OFF.

(b) Depress the brake pedal more than 20 times.

(c) Turn the ignition switch to the ON position.

(d) Check how the hydraulic brake booster pump motor operates.

Result

Proceed to

Pump motor does not operate

A

Pump motor operates continuously (Does not stop)

B

Pump motor operates intermittently

C

Pump motor operates, then stops

D

B

REPLACE HYDRAULIC BRAKE BOOSTER

C

GO TO STEP 4

D

GO TO STEP 5

A

2.

CHECK BRAKE PUMP MOTOR WIRE HARNESS CONNECTION (MT+ / MT-)

(a) Using a screwdriver, remove the 2 plugs from the hydraulic brake booster (See page (b) Check the tightening torque of 2 screws which fasten the wire harness connecting ).

(b) Check the tightening torque of 2 screws which fasten the wire harness connecting hydraulic brake booster and brake booster pump (See page Torque: ).

Torque:

2.9 N·m {30 kgf·cm, 26 in·lbf}

NG

RETIGHTEN SCREWS

OK

3.

CHECK RESISTANCE OF PUMP MOTOR WIRE HARNESS (MT+/MT-)

(a) Using a screwdriver, remove the 2 screws and pull the wire harness from the hydraulic brake booster assembly.

(b) Measure the resistance between the red wire (MT+) and black wire (MT-).

Resistance:

2 Ω

NG

REPLACE HYDRAULIC BRAKE BOOSTER

OK

4.

READ VALUE USING DATA LIST (ACCUMULATOR SENSOR)

(a) Connect Techstream to the DLC3.

(b) Turn the ignition switch to the ON position.

(c) Turn Techstream ON.

(d) Select the Data List mode on the Techstream.

ABS/VSC/TRAC

Tester Display

Measurement Item / Range

Normal Condition

Diagnostic Note

Accumulator Sensor

Accumulator pressure sensor reading / min.: 0 V, max.: 5 V

3.58 to 5 V

If value constant regardless of pump operation, accumulator pressure sensor malfunction suspected.

(e) Check that the accumulator pressure sensor output is normal.

Result

Proceed to

Output value varies within "Normal Condition" range

A

Output value does not reach "Normal Condition" range

B

Output value constant regardless of pump motor operation

C

B

REPLACE MASTER CYLINDER SOLENOID

C

REPLACE HYDRAULIC BRAKE BOOSTER

A

5.

RECONFIRM DTC

(a) Clear the DTCs (See page ). (b) Turn the ignition switch to OFF. ).

(b) Turn the ignition switch to OFF.

(c) Turn the ignition switch to the ON position.

(d) Wait for more than 5 minutes.

(e) Check if the same DTCs are recorded.

Result

Proceed to

DTC output

A

DTC not output

B

A

REPLACE MASTER CYLINDER SOLENOID

B

REPLACE HYDRAULIC BRAKE BOOSTER

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