Lexus IS250 · Service Manual BRAKE

C0278/11

Diagnostic trouble codes

DESCRIPTION

The ABS solenoid relay supplies power to the ABS solenoid and TRC solenoid.
The solenoid relay is turned on 1.5 seconds after the engine switch is turned on (IG), and is turned off if an open or short in the solenoid is detected by self diagnosis performed when the vehicle starts running.
The ABS solenoid relay is housed in the skid control ECU in the actuator assembly.

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.

DTC No.
 DTC Detection Condition
 Trouble Area
C0278/11
 When any of the following (1 or 2) is detected:
  1. All of the following conditions continue for 0.2 seconds or more.
    1. The IG1 terminal voltage is between 9.5 and 17.2 V.
    2. The solenoid relay contact is open when the relay is ON.
  2. All of the following conditions continue for 0.2 seconds or more.
    1. IG1 terminal voltage becomes lower than 9.5 V or less when the relay is turned on.
    2. The relay contact remains open.
  1. ABS2 fuse
  2. ABS solenoid relay
  3. ABS solenoid relay circuit
  4. Brake actuator assembly
C0279/12
 Immediately after the engine switch is turned on (IG), the solenoid relay contact is closed for 0.2 seconds when the relay is turned off.
 Brake actuator assembly

WIRING DIAGRAM

C109386E03

INSPECTION PROCEDURE

NOTICE:
When replacing the brake actuator assembly, perform zero point calibration (Click here).


1. INSPECT ABS2 FUSE

  1. C109429E02
    Remove the ABS2 fuse from engine room No. 1 R/B.

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

    Standard resistance:
    Tester Connection
    		 Condition
    		 Specified Condition
    ABS2 (30A) fuse
    		 Always
    		 Below 1 Ω



NG
REPLACE ABS2 FUSE
OK


2. INSPECT SKID CONTROL ECU (+BS AND GND TERMINAL)

  1. F049362E28
    Install the ABS2 fuse.

  1. Disconnect the skid control ECU connector.

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

    Standard voltage:
    Tester Connection
    		 Condition
    		 Specified Condition
    A14-31 (+BS) - Body ground
    		 Always
    		 10 to 14 V

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

    Standard resistance:
    Tester Connection
    		 Condition
    		 Specified Condition
    A14-32 (GND1) - Body ground
    		 Always
    		 Below 1 Ω
    A14-1 (GND2) - Body ground
    		 Always
    		 Below 1 Ω



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR (+BS OR GND CIRCUIT)
OK


3. RECONFIRM DTC

  1. Reconnect the skid control ECU connector.

  1. Clear the DTC (Click here).

  1. Start the engine.

  1. Drive the vehicle at the speed of 4 mph (6 km/h) or more.

  1. Check if the same DTC is recorded (Click here).

    Result:
    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:
    1. 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.
    2. If the normal system code is output (the trouble code is not output), slightly jiggle the connectors, wire harnesses, and fuses of the brake actuator assembly. Make sure that no DTCs are output.
    3. If any DTCs are output while jiggling a connector or wire harness of the brake actuator (skid control ECU), inspect and repair the connector or wire harness.



 B
REPLACE BRAKE ACTUATOR ASSEMBLY
A

USE SIMULATION METHOD TO CHECK


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