BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: ELECTRONICALLY CONTROLLED BRAKE SYSTEM (for HV Model): C1242; Open Circuit in IG1/IG2 Power Source Circuit; 2020 - 2022 MY Corolla Corolla HV [01/2019

Last Modified: 07-31-2024	6.11:8.1.0	Doc ID: RM100000001G78X
Model Year Start: 2020	Model: Corolla	Prod Date Range: [01/2019 - 09/2022]
Title: BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: ELECTRONICALLY CONTROLLED BRAKE SYSTEM (for HV Model): C1242; Open Circuit in IG1/IG2 Power Source Circuit; 2020 - 2022 MY Corolla Corolla HV [01/2019 - 09/2022]

DTC

C1242

Open Circuit in IG1/IG2 Power Source Circuit

DESCRIPTION

Refer to DTC C1241.

Click here

DTC No.

Detection Item

INF Code

DTC Detection Condition

Trouble Area

MIL

Note

C1242

Open Circuit in IG1/IG2 Power Source Circuit

111

112

INF Code: 111
- When the IG1 terminal voltage is less than 3.5 V, the IG2 terminal voltage is 9.5 V or more for 4 seconds or more.
INF Code: 112
- When communication with the hybrid vehicle control ECU is normal or the vehicle speed is 10 km/h (6 mph) or more, and the IG1 terminal voltage is 9.5 V or more, the IG2 terminal voltage is less than 3.5 V for 4 seconds or more.

INF Code: 111
- Open or short in IG1 circuit
- Improperly connected connector, deformation or corrosion of terminals
- Smart key system (IG start circuit)
- Auxiliary battery
- Hybrid control system (Charging circuit)
- Skid control ECU (brake booster with master cylinder assembly)
INF Code: 112
- Open or short in IG2 circuit
- Improperly connected connector, deformation or corrosion of terminals
- Smart key system (IG start circuit)
- Auxiliary battery
- Hybrid control system (Charging circuit)
- Skid control ECU (brake booster with master cylinder assembly)

Comes on

INF Code 111: SAE Code C123B
INF Code 112: SAE Code C123E
Electronically controlled brake system DTC

MONITOR DESCRIPTION

During normal operation, the voltage at IG1 and IG2 change mutually; however, if the voltages do not change mutually such as when IG1 is on and IG2 is off or when IG1 is off and IG2 is on, the skid control ECU (brake booster with master cylinder assembly) judges that there is an open in the IG1 or IG2 circuit and illuminates the MIL and stores a DTC.

MONITOR STRATEGY

Related DTCs	C123B: IG1 circuit low C123E: IG2 circuit low
Required Sensors/Components(Main)	Skid control ECU (brake booster with master cylinder assembly)
Required Sensors/Components(Related)	Speed sensor Skid control ECU (brake booster with master cylinder assembly)
Frequency of Operation	Continuous
Duration	4 seconds
MIL Operation	Immediately
Sequence of Operation	None

TYPICAL ENABLING CONDITIONS

C123B

Monitor runs whenever the following DTCs are not stored	None
IG2 voltage	Higher than 9.5 V

C123E

Monitor runs whenever the following DTCs are not stored	None
Both of the following conditions are met	A and B
A. IG1 voltage	Higher than 9.5 V
B. Either of the following condition is met	-
Vehicle speed	Higher than 10 km/h (6 mph)
Communication status with hybrid control system	Valid

TYPICAL MALFUNCTION THRESHOLDS

C123B

IG1

Off

C123E

IG2

Off

COMPONENT OPERATING RANGE

C123B

Both of the following conditions are met	-
IG2 voltage	Higher than 9.5 V
IG1	On

C123E

Both of the following conditions are met	-
IG1 voltage	Higher than 9.5 V
IG2	On

CONFIRMATION DRIVING PATTERN

Connect the Techstream to the DLC3.
Turn the power switch on (IG).
Turn the Techstream on.
Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
Turn the power switch off.
Turn the power switch on (READY).
Turn the Techstream on.
Drive the vehicle at 10 km/h (6 mph) or more for 4 seconds or more.
Enter the following menus: Chassis / ABS/VSC/TRAC / Trouble Codes.
Read the DTCs.
HINT:
- If a DTC is output, the system is malfunctioning.
- If a DTC is not output, perform the following procedure.
If the DTCs are not output, perform a universal trip and check for permanent DTCs.
Click here
HINT:
- If a permanent DTC is output, the system is malfunctioning.
- If no permanent DTCs are output, the system is normal.

WIRING DIAGRAM

Refer to DTC C1241.

Click here

CAUTION / NOTICE / HINT

NOTICE:

After replacing the skid control ECU (brake booster with master cylinder assembly), perform linear solenoid valve offset learning, ABS holding solenoid valve learning, yaw rate and acceleration sensor zero point calibration and system information memorization after performing "Reset Memory".
Click here
Inspect the fuses for circuits related to this system before performing the following procedure.

PROCEDURE

1.	CHECK FREEZE FRAME DATA

(a) Check the INF code from the Freeze Frame Data stored when DTC (C1242) was stored.

Click here

Chassis > ABS/VSC/TRAC > Trouble Codes

Result	Proceed to
INF code 111 is output.	A
INF code 112 is output.	B

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY

2.	CHECK HARNESS AND CONNECTOR (IG1 AND IG2 TERMINAL)

(a) Turn the power switch off.

*a	Front view of wire harness connector (to Skid Control ECU (Brake Booster with Master Cylinder Assembly))

(b) Make sure that there is no looseness at the locking part and the connecting part of the connector.

OK:

The connector is securely connected.

(d) Check both the connector case and the terminals for deformation and corrosion.

OK:

No deformation or corrosion.

(e) Turn the power switch on (IG).

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
A48-23 (IG1) - Body ground	Power switch on (IG)	11 to 14 V
A48-9 (IG2) - Body ground	Power switch on (IG)	11 to 14 V

Result	Proceed to
11 to 14 V.	A
Below 11 V.	B

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY

REPAIR OR REPLACE HARNESS OR CONNECTOR (IG1 AND/OR IG2 CIRCUIT)