VEHICLE STABILITY CONTROL SYSTEM(for Hydraulic Brake Booster), Diagnostic DTC:C1242

DTC Code DTC Name
C1242 Open Circuit in IG1/IG2 Power Source Circuit

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.

If the voltage supplied to the IG2 terminal is within the DTC detection range due to malfunctions in components such as the battery and generator circuit, this DTC is stored.

DTC Code DTC Detection Condition Trouble Area
C1242 The vehicle speed is 3 km/h (2 mph) or more and the voltage at the ECU IG2 terminal remains below 6.5 V for more than 7 seconds.

  • Battery

  • IGN fuse

  • Charging system

  • Harness or connector

  • Master cylinder solenoid (Skid control ECU)

WIRING DIAGRAM

B001IMBE21
*a from IG2 Circuit
*b Master Cylinder Solenoid (Skid Control ECU)

CAUTION / NOTICE / HINT

Note


  • When replacing the master cylinder solenoid, perform calibration Click here.

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

PROCEDURE


  1. CHECK TERMINAL VOLTAGE (IG2)


    1. Disconnect the A8 skid control ECU connector.

    2. B001IMAE04
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Skid Control ECU)

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      A8-1 (IG2) - Body ground Ignition switch ON 11 to 14 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

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


    1. Disconnect the A7 and A8 skid control ECU connectors.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A7-1 (GND1) - Body ground Always Below 1 Ω
      A7-32 (GND2) - Body ground Always Below 1 Ω
      A8-4 (GND3) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. RECONFIRM DTC


    1. Clear the DTCs Click here.

    2. Check if the same DTC is output Click here.

      Tech Tips

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

      Result
      Result Proceed to
      DTC is not output A
      DTC is output (for LHD) B
      DTC is output (for RHD) C

    A

    USE SIMULATION METHOD TO CHECK Click here

    B

    REPLACE MASTER CYLINDER SOLENOID Click here

    C

    REPLACE MASTER CYLINDER SOLENOID Click here