BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: ELECTRONICALLY CONTROLLED BRAKE SYSTEM (w/o Vacuum Brake Booster): C123D00; IG2 Malfunction; 2022 - 2025 MY RAV4 RAV4 HV [12/2021

Last Modified: 05-08-2025	6.11:8.1.0	Doc ID: RM10000000214RF
Model Year Start: 2022	Model: RAV4	Prod Date Range: [12/2021 - ]
Title: BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: ELECTRONICALLY CONTROLLED BRAKE SYSTEM (w/o Vacuum Brake Booster): C123D00; IG2 Malfunction; 2022 - 2025 MY RAV4 RAV4 HV [12/2021 - ]

DTC

C123D00

IG2 Malfunction

DESCRIPTION

Refer to DTC C110E14.

Click here

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	MIL	Note
C123D00	IG2 Malfunction	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 10.2 V or more, the IG2 terminal voltage is less than 2.8 V for 4 seconds or more.	Open or short in IG2 circuit Improperly connected connector, deformation or corrosion of terminals No. 1 skid control ECU (brake booster with master cylinder assembly)	Comes on	SAE Code: C123E (Case 1) Output ECU: Both skid control ECUs

C123D00 DTC Detection Conditions

		Vehicle Condition
		Pattern 1	Pattern 2
Diagnosis Condition	When communication with the hybrid vehicle control ECU is normal	○	-
Diagnosis Condition	The vehicle speed is 10 km/h (6 mph) or more	-	○
Malfunction Status	The IG1 terminal voltage is 10.2 V or more, the IG2 terminal voltage is less than 2.8 V	○	○
Detection Time		4 seconds or more.	4 seconds or more.
Number of Trips		1 trip	1 trip

HINT:

DTC will be output when conditions for either of the patterns in the table above are met.

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, the No. 2 skid control ECU (brake actuator assembly) judges that there is an open in the IG2 circuit and illuminates the MIL and stores this DTC.

MONITOR STRATEGY

Related DTCs	C123E (Case 1): Brake system voltage input open circuit
Required Sensors/Components(Main)	No. 2 skid control ECU (brake actuator assembly)
Required Sensors/Components(Related)	Speed sensor No. 2 skid control ECU (brake actuator assembly)
Frequency of Operation	Continuous
Duration	3.996 seconds
MIL Operation	Immediately
Sequence of Operation	None

TYPICAL ENABLING CONDITIONS

Monitor runs whenever the following DTCs are not stored	C1241: Brake system voltage input out of range low
Both of the following conditions are met	A and B
A. IG1 voltage	Higher than 10.2 V
B. Either of the following conditions is met	-
The second highest speed sensor output value	Higher than 10 km/h (6.21 mph)
Communication status with hybrid control system	Valid

TYPICAL MALFUNCTION THRESHOLDS

IG2 voltage

Less than 2.8 V

COMPONENT OPERATING RANGE

Both of the following conditions are met	-
IG1 voltage	Higher than 10.2 V
IG2 voltage	3.8 V or more

CONFIRMATION DRIVING PATTERN

NOTICE:

When performing the normal judgment procedure, make sure that the driver door is closed and is not opened at any time during the procedure.

HINT:

After repair has been completed, clear the DTC and then check that the vehicle has returned to normal by performing the following All Readiness check procedure.
When clearing the permanent DTCs, refer to the "CLEAR PERMANENT DTC" procedure.

Connect the GTS to the DLC3.
Turn the ignition switch to ON and turn the GTS on.
Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
Turn the ignition switch off.
Turn the ignition switch to ON (READY) and turn the GTS on.
Wait for 4 seconds or more. [*]
HINT:

[*]: Normal judgment procedure.

The normal judgment procedure is used to complete DTC judgment and also used when clearing permanent DTCs.
Enter the following menus: Chassis / Brake/EPB / Utility / All Readiness.
Check the DTC judgment result.
HINT:
- If the judgment result shows NORMAL, the system is normal.
- If the judgment result shows ABNORMAL, the system has a malfunction.
- If the judgment result shows INCOMPLETE, perform driving pattern again.

WIRING DIAGRAM

Refer to DTC C110E14.

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CAUTION / NOTICE / HINT

NOTICE:

Inspect the fuses for circuits related to this system before performing the following procedure.
Before performing troubleshooting, make sure to confirm that the auxiliary battery voltage is normal.
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After replacing the No. 1 skid control ECU (brake booster with master cylinder assembly), perform "Calibration" after performing "Reset Memory".
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PROCEDURE

1.	CHECK HARNESS AND CONNECTOR (IG2 TERMINAL)

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

OK:

The connector is securely connected.

*a	Front view of wire harness connector (to No. 1 Skid Control ECU (Brake Booster with Master Cylinder Assembly))

(b) Disconnect the A104 No. 1 skid control ECU (brake booster with master cylinder assembly) connector.

OK:

No deformation or corrosion.

(d) Turn the ignition switch to ON.

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
A104-42 (IG2) - Body ground	Ignition switch ON	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