VEHICLE STABILITY CONTROL SYSTEM, Diagnostic DTC:C1241

DTC Code	DTC Name
C1241	Low Power Supply Voltage Malfunction

DESCRIPTION

If a malfunction is detected in the power supply circuit, the skid control ECU (brake actuator assembly) stores this DTC and the fail-safe function prohibits ABS operation. This DTC is stored when the +BS terminal voltage deviates due to a malfunction in the power supply or charging circuit such as the battery or alternator circuit, etc. The DTC is cleared when the +BS terminal voltage returns to normal.


DTC No.	Detection Item	DTC Detection Condition	Trouble Area	Note
C1241	Low Power Supply Voltage Malfunction	Any of the following is detected: The vehicle speed is 6 km/h (4 mph) or more and the +BS terminal voltage (soft low voltage) is less than 9.6 V for 1 second or more. The vehicle speed is 6 km/h (4 mph) or more and the +BS terminal voltage (hard low voltage) is less than 6.9 V for 1 second or more. The vehicle speed is 15 km/h (9 mph) or more, the +BS terminal voltage is 9.6 V or more, the skid control ECU (brake actuator assembly) turns on more than one valve at the same time within a short period of time and the valve relay supply voltage drop exceeds the threshold.* The +BS terminal voltage is less than 6.7 V and the skid control ECU (brake actuator assembly) judges that power supply voltage is abnormal for 0.06 seconds or more.	ABS NO. 2 fuse Battery Charging system Power source circuit Ground circuit Internal power supply circuit of the skid control ECU (brake actuator assembly)	Tire pressure warning light (w/ tire pressure warning system) blinks for 63 seconds and then remains on.

*: The skid control ECU (brake actuator assembly) monitors the resistance of the power source line at the +BS terminal. A malfunction is detected when an abnormality occurs in the +BS terminal wire harness or its connection and the skid control ECU (brake actuator assembly) determines that the wiring resistance at the +BS terminal exceeds the standard resistance.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

Note:

When replacing the skid control ECU (brake actuator assembly), perform system variant learning and acceleration sensor zero point calibration.
Click here
Inspect the fuses for circuits related to this system before performing the following procedure.

PROCEDURE

CHECK BATTERY

Check the battery voltage.

Standard Voltage

11 to 14 V

Result


Proceed to
OK
NG

NG

CHECK OR REPLACE CHARGING SYSTEM COMPONENT OR BATTERY

w/ Stop and Start System:Click here

w/o Stop and Start System:Click here

OK

CHECK HARNESS AND CONNECTOR (POWER SOURCE TERMINAL)

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

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

Disconnect the A39 skid control ECU (brake actuator assembly) connector.

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

Standard Voltage


Tester Connection	Condition	Specified Condition
A39-25 (+BS) - Body ground	Always	11 to 14 V
A39-25 (+BS) - A39-38 (GND1)	Always	11 to 14 V
A39-28 (IG1) - Body ground	Ignition switch ON	11 to 14 V1 9.5 to 14 V2
A39-28 (IG1) - A39-38 (GND1)	Ignition switch ON	11 to 14 V1 9.5 to 14 V2

*1: w/o Stop and Start System
*2: w/ Stop and Start System

Result


Result	Proceed to
OK	A
NG (for +BS circuit)	B
NG (w/o Stop and start system for IG1 circuit)	C
NG (w/ Stop and start system for IG1 circuit)	D

B

CHECK HARNESS AND CONNECTOR (BRAKE ACTUATOR ASSEMBLY - NO. 1 ENGINE ROOM RELAY BLOCK)Click here

C

REPAIR OR REPLACE HARNESS OR CONNECTOR (IG1 CIRCUIT)

D

INSPECT STOP AND START SYSTEM (BACKUP BOOST CONVERTER CIRCUIT)

Click here

A

CHECK HARNESS AND CONNECTOR (GND1 TERMINAL)

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

Turn the ignition switch off.

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

Standard Resistance


Tester Connection	Condition	Specified Condition
A39-38 (GND1) - Body ground	Always	Below 1 Ω

Result


Proceed to
OK
NG

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (GND1 CIRCUIT)

OK

RECONFIRM DTC

Reconnect the A39 skid control ECU (brake actuator assembly) connector.
Clear the DTCs.
Click here

Chassis > ABS/VSC/TRC > Clear DTCs
Turn the ignition switch off.
Start the engine.
Perform a road test.

Check if the same DTC is output.

Click here

Chassis > ABS/VSC/TRC > Trouble Codes

Result


Result	Proceed to
DTC C1241 is not output.	A
DTC C1241 is output.	B

Tip:

If troubleshooting has been carried out according to Problem Symptoms Table, refer back to the table and proceed to the next step before replacing parts.

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A

USE SIMULATION METHOD TO CHECK

Click here

B

REPLACE BRAKE ACTUATOR ASSEMBLY

Click here

CHECK HARNESS AND CONNECTOR (BRAKE ACTUATOR ASSEMBLY - NO. 1 ENGINE ROOM RELAY BLOCK)

Turn the Ignition Switch off.
Disconnect the 1A No. 1 engine room relay block connector.

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

Standard Resistance


Tester Connection	Condition	Specified Condition
A39-25 (+BS) - 1A-1	Always	Below 1 Ω

Tip:

Even if the resistance between the skid control ECU (brake actuator assembly) and the No. 1 engine room relay block is normal, there may be an abnormality in the resistance of the wiring between the battery and the No. 1 engine room relay block. Therefore, be sure to inspect the circuit between the battery and the No. 1 engine room relay block before replacing the skid control ECU (brake actuator assembly).
If troubleshooting has been carried out according to Problem Symptoms Table, refer back to the table and proceed to the next step before replacing parts.
Click here

Result


Proceed to
OK
NG

OK

REPLACE BRAKE ACTUATOR ASSEMBLY

Click here

NG

REPAIR OR REPLACE WIRE HARNESS OR NO. 1 ENGINE ROOM RELAY BLOCK