Toyota 4Runner Quiz
Brake

Open in ABS Solenoid Relay Circuit (C0278,C0279)

In this manual: Brake
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2steps
~12min
1/5difficulty
Done 0 of 2
DESCRIPTION

The solenoid relay is built into the master cylinder solenoid.

This relay supplies power to each solenoid. If the initial check is OK, after the ignition switch is turned to ON, the relay turns on.

DTC Code

DTC Detection Condition

Trouble Area

C0278

Either condition is met:

  1. Both of the following conditions continue for at least 0.2 seconds.
    1. IG voltage is between 9.5 and 17 V.
    2. The relay contact is open when the relay is on.
  2. Both of the following conditions continue for at least 0.2 seconds.
    1. IG voltage is 9.5 V or less when the relay is on.
    2. The relay contact remains open.
  • ABS NO. 2 fuse
  • Solenoid relay circuit
  • Master cylinder solenoid

C0279

The following condition continues for at least 0.2 seconds.

  • The relay contact is closed immediately after turning the ignition switch to ON when the relay is off.
WIRING DIAGRAM

Refer to DTCs C0226, C0236, C0246, C0256, C1225, C1226, C1227 and C1228 (See page ).


CAUTION / NOTICE / HINT

NOTICE:

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

  • Inspect the fuses for circuits related to this system before performing the following inspection procedure.
PROCEDURE

  1. CHECK TERMINAL VOLTAGE (+BS)

(a) Disconnect the A6 skid control ECU connector.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

A6-31 (+BS) - Body ground

Always

11 to 14 V
Text in Illustration

*a

Front view of wire harness connector

(to Skid Control ECU)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

  1. CHECK HARNESS AND CONNECTOR (GND1, GND2 AND GND3 TERMINAL)

(a) Disconnect the A6 and A7 skid control ECU connectors.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

A6-1 (GND1) - Body ground

Always

Below 1 Ω

A6-32 (GND2) - Body ground

Always

Below 1 Ω

A7-4 (GND3) - Body ground

Always

Below 1 Ω

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

  1. RECONFIRM DTC

HINT:

These codes are stored when a problem is detected in the master cylinder solenoid.

The solenoid relay is in the master cylinder solenoid.

Therefore, solenoid relay circuit inspections and relay unit inspections cannot be performed. Be sure to check if any DTC is output before replacing the master cylinder solenoid.

(a) Clear the DTCs (See page ).


(b) Drive the vehicle at a speed of approximately 32 km/h or more for 60 seconds or more.

(c) Check if the same DTCs are output (See page ).


HINT:

Reinstall the sensors, connectors, etc. and restore the previous vehicle conditions before rechecking for DTCs.

Result

Result

Proceed to

DTC is output

A

DTC is not output

B

A

REPLACE MASTER CYLINDER SOLENOID

B

USE SIMULATION METHOD TO CHECK

Test yourself

A quick Toyota 4Runner quiz: every answer comes with an explanation and a link to the manual page.