DTC C0278/11 Open in ABS Solenoid Relay Circuit; DTC C0279/12 Short to B+ in ABS Solenoid Relay Circuit: Wiring Diagram

WARNING: This page is about a different car, the 2006 Lexus IS 350. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Wiring Diagram

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

NOTE: When replacing the skid control ECU, perform zero point calibration (See CALIBRATION ).

INSPECT ABS3 FUSE

Remove the ABS3 fuse from engine room No. 1 R/B.

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

Standard resistance

TESTER CONNECTION AND SPECIFIED CONDITION CHART

Tester Connection	Condition	Specified Condition
ABS3 (25 A) fuse	Always	Below 1 Ω

Fig 2: Inspecting ABS3 Fuse

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

NG : REPLACE ABS3 FUSE

OK : GO TO NEXT STEP

INSPECT ABS SOLENOID RELAY

Install the ABS3 fuse.
Remove the ABS SOL relay.

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

Standard resistance

TESTER CONNECTION AND SPECIFIED CONDITION CHART

Tester Connection	Condition	Specified Condition
3 - 5	Always	10 kΩ or higher
3 - 5	Apply B+ between terminals 1 and 2	Below 1 Ω

Fig 3: Inspecting ABS Solenoid Relay

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

NG : REPLACE ABS SOLENOID RELAY

OK : GO TO NEXT STEP

INSPECT ENGINE ROOM NO. 3 RELAY BLOCK (POWER SOURCE TERMINAL)

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

Standard voltage

TESTER CONNECTION AND SPECIFIED CONDITION CHART

Tester Connection	Condition	Specified Condition
ABS SOL relay terminal 3 - Body ground	Always	10 to 14 V

Fig 4: Inspecting Engine Room No. 3 Relay Block (Power Source Terminal)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

NG : REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)

OK : GO TO NEXT STEP

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

Disconnect the skid control ECU connectors.

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

Standard resistance

TESTER CONNECTION AND SPECIFIED CONDITION CHART

Tester Connection	Condition	Specified Condition
A35-11 (R+) - ABS SOL relay terminal 1	Always	Below 1 Ω
A35-11 (R+) - Body ground	Always	10 kΩ or higher
J78-2 (SR) - ABS SOL relay terminal 2	Always	Below 1 Ω
J78-2 (SR) - Body ground	Always	10 kΩ or higher
J78-13 (AST) - ABS SOL relay terminal 5	Always	Below 1 Ω
J78-13 (AST) - Body ground	Always	10 kΩ or higher

Fig 5: Checking Harness And Connector (Skid Control ECU - Engine Room No. 3 Relay Block)

NG : REPAIR OR REPLACE HARNESS OR CONNECTOR

OK : GO TO NEXT STEP

RECONFIRM DTC

Install the ABS SOL relay.
Reconnect the skid control ECU connectors.
Clear the DTC (See DTC CHECK / CLEAR ).
Start the engine.
Drive the vehicle at the speed of 4 mph (6 km/h) or more.

Check if the same DTC is recorded (See DTC CHECK / CLEAR ).

Result

CONDITION CHART

Condition	Proceed to
DTCs (C0278/11 and/or C0279/12) are not output	A
DTCs (C0278/11 and/or C0279/12) are output	B

HINT:

If a speed signal of 4 mph (6 km/h) or more is input to the skid control ECU, with the engine switch on (IG) and the stop light switch off, the ECU performs self diagnosis of the motor and solenoid circuits.
If the normal system code is output (the trouble code is not output), slightly jiggle the connectors, wire harnesses, and fuses of the skid control ECU and brake actuator assembly. Make sure that no DTCs are output.
If any DTCs are output while jiggling a connector or wire harness of the skid control ECU and brake actuator assembly, inspect and repair the connector or wire harness.

B : REPLACE SKID CONTROL ECU

A : USE SIMULATION METHOD TO CHECK