Toyota 4Runner: Open Circuit in IG1/IG2 Power Source Circuit (C1242)

Toyota 4Runner Service Manual / Brake / Brake Control / Dynamic Control Systems / Vehicle Stability Control System(for Hydraulic Brake Booster) / Open Circuit in IG1/IG2 Power Source Circuit (C1242)

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 (1.9 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

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 (IG2)

(a) Disconnect the A7 skid control ECU connector.

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

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
A7-1 (IG2) - Body ground	Ignition switch ON	11 to 14 V

Text in Illustration

*a	Front view of wire harness connector (to Skid Control ECU)

REPAIR OR REPLACE HARNESS OR CONNECTOR

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

REPAIR OR REPLACE HARNESS OR CONNECTOR

3.	RECONFIRM DTC

(a) Clear the DTCs (See page ).

(b) Turn the ignition switch off.

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

REPLACE MASTER CYLINDER SOLENOID

USE SIMULATION METHOD TO CHECK

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