Toyota 4Runner manuals

Toyota 4Runner: Open in Pump Motor Circuit (C1251)

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.

DTC Code

DTC Detection Condition

Trouble Area

C1251

There is an open in the motor system circuit (motor input circuit).

  • Pump motor wire harness connection
  • Brake booster with accumulator pump assembly
  • Master cylinder solenoid (Skid control ECU)

CAUTION / NOTICE / HINT

NOTICE:

When replacing the master cylinder solenoid, perform calibration (See page ).


HINT:

Remove the hydraulic brake booster assembly before the inspection (See page ).


PROCEDURE

1.

CHECK CONNECTION OF PUMP MOTOR WIRE HARNESS

(a) Remove the hydraulic brake booster assembly (See page ).


(b) Check the tightening torque of the 2 screws which secure the wire harness connecting the master cylinder solenoid and brake booster with accumulator pump assembly (See page ).


OK:

The harness is tightened to the specified torque.

Torque:

2.9 N·m {30 kgf·cm, 26 in·lbf}


NG

RETIGHTEN SCREWS

OK

2.

CHECK RESISTANCE OF PUMP MOTOR WIRE HARNESS

(a) Using a screwdriver, remove the 2 screws and pull out the wire harness from the master cylinder solenoid.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

Red wire terminal - Black wire terminal

Always

Below 2 Ω

Text in Illustration

*1

Pump motor wire harness

*a

Red wire

*b

Black wire



NG

REPLACE BRAKE BOOSTER WITH ACCUMULATOR PUMP ASSEMBLY

OK

3.

RECONFIRM DTC

(a) Reassemble the hydraulic brake booster assembly (See page ).


(b) Install the hydraulic brake booster assembly (See page ).


(c) Clear the DTCs (See page ).


(d) Turn the ignition switch off.

(e) Check if the same DTC is output (See page
).

Result

Result

Proceed to

DTC is output

A

DTC is not output

B


A

REPLACE MASTER CYLINDER SOLENOID


B

USE SIMULATION METHOD TO CHECK

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DESCRIPTION If there is a problem with the master cylinder solenoid (skid control ECU) power supply circuit, the skid control ECU stores DTCs and prohibits operation under the fail-safe function. ...

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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. DTC Code D ...

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