Diagnostic trouble code C1242 Land Cruiser

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

INSPECT BATTERY

INSPECT IGN FUSE

INSPECT SKID CONTROL ECU (IG2 TERMINAL)

INSPECT SKID CONTROL ECU (GND TERMINAL)

RECONFIRM DTC

DTC C1242/42 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 alternator circuit, this DTC is stored.

DTC Code DTC Detection Condition Trouble Area
C1242/42 The vehicle speed is 3 km/h (1.9 mph) or more and the voltage of the ECU IG2 terminal remains below 6.5 V for more than 7 seconds.
  1. Battery
  2. IGN fuse
  3. Charging system
  4. Harness or connector
  5. Master cylinder solenoid (Skid control ECU)

Wiring diagram

Diagnostic trouble code C1242 Land Cruiser. Wiring diagram

Inspection procedure

NOTICE:

When replacing the master cylinder solenoid, perform zero point calibration .

1.INSPECT BATTERY

  1. Check the battery voltage.

    Standard voltage:

    11 to 14 V

    Result
    Result Proceed to
    OK A
    NG 1GR-FE B
    2UZ-FE C
    1VD-FTV D
  B  
GO TO CHARGING SYSTEM (ON-VEHICLE INSPECTION)
 
  C  
GO TO CHARGING SYSTEM (ON-VEHICLE INSPECTION)
 
  D  
GO TO CHARGING SYSTEM (ON-VEHICLE INSPECTION)
 
A  
   

2.INSPECT IGN FUSE

Diagnostic trouble code C1242 Land Cruiser. Remove the IGN fuse from the engine room relay block.

  1. Remove the IGN fuse from the engine room relay block.

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

    Standard Resistance:

    Tester Connection Condition Specified Condition
    IGN fuse Always Below 1 ?
  NG  
REPLACE IGN FUSE
 
OK  
   

3.INSPECT SKID CONTROL ECU (IG2 TERMINAL)

  1. Install the IGN fuse.

Diagnostic trouble code C1242 Land Cruiser. Disconnect the A25 skid control ECU connector.

  1. Disconnect the A25 skid control ECU connector.

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

    Standard Voltage:

    Tester Connection Switch Condition Specified Condition
    A25-1 (IG2) - Body ground Ignition switch ON 11 to 14 V
  NG  
REPAIR OR REPLACE HARNESS OR CONNECTOR
 
OK  
   

4.INSPECT SKID CONTROL ECU (GND TERMINAL)

Diagnostic trouble code C1242 Land Cruiser. Disconnect the A24 and A25 skid control ECU connectors.

  1. Disconnect the A24 and A25 skid control ECU connectors.

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

    Standard Resistance:

    Tester Connection Condition Specified Condition
    A24-1 (GND1) - Body ground Always Below 1 ?
    A24-32 (GND2) - Body ground Always Below 1 ?
    A25-4 (GND3) - Body ground Always Below 1 ?
  NG  
REPAIR OR REPLACE HARNESS OR CONNECTOR
 
OK  
   

5.RECONFIRM DTC

  1. Clear the DTC .

  1. Check if the same DTC is output .

    HINT:

    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 LHD B
    RHD C
  B  
REPLACE MASTER CYLINDER SOLENOID
 
  C  
REPLACE MASTER CYLINDER SOLENOID
 
A  
   
USE SIMULATION METHOD TO CHECK