Toyota Avalon Service & Repair Manual: Low or High Power Supply Voltage (C1241)

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 meets one of the DTC detection conditions 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

C1241

Low or High Power Supply Voltage

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)

*: 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.

DTC Detection Conditions: C1241
 

Vehicle Condition

Pattern 1

Pattern 2

Pattern 3

Pattern 4

Diagnosis Condition

The vehicle speed is 6 km/h (4 mph) or more.

-

-

The vehicle speed is 15 km/h (9 mph) or more and the +BS terminal voltage is 9.6 V or more.

-

-

-

The +BS terminal voltage is less than 6.7 V.

-

-

-

Malfunction Status

The +BS terminal voltage (soft low voltage) is less than 9.6 V.

-

-

-

The +BS terminal voltage (hard low voltage) is less than 6.9 V.

-

-

-

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 skid control ECU (brake actuator assembly) judges that power supply voltage is abnormal.

-

-

-

Detection Time

1 second or more

1 second or more

-

0.06 seconds or more

Number of Trips

1 trip

1 trip

1 trip

1 trip

*: 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.

HINT:

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

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • 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

1.

CHECK BATTERY

(a) Check the battery voltage.

Standard Voltage:

Tester Connection

Condition

Specified Condition

Positive (+) terminal - Negative (-) terminal

Engine switch off

11 to 14 V

NG

CHECK OR REPLACE CHARGING SYSTEM COMPONENT OR BATTERY

OK

2.

CHECK HARNESS AND CONNECTOR (POWER SOURCE 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 Skid Control ECU (Brake Actuator Assembly))

(b) Disconnect the A28 skid control ECU (brake actuator assembly) connector.

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

OK:

No deformation or corrosion.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

A28-30 (+BS) - Body ground

Always

11 to 14 V

A28-36 (IG1) - Body ground

Engine switch on (IG)

11 to 14 V

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)

OK

3.

CHECK HARNESS AND CONNECTOR (GND1 TERMINAL)

(a) Turn the engine switch off.

*a

Front view of wire harness connector

(to Skid Control ECU (Brake Actuator Assembly))

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

A28-46 (GND1) - Body ground

Always

Below 1 Ω

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (GND1 CIRCUIT)

OK

4.

RECONFIRM DTC

(a) Reconnect the A28 skid control ECU (brake actuator assembly) connector.

(b) Clear the DTCs.

Chassis > ABS/VSC/TRAC/EPB > Clear DTCs

(c) Turn the engine switch off.

(d) Start the engine.

(e) Perform a road test.

(f) Check if the same DTC is output.

Chassis > ABS/VSC/TRAC/EPB > Trouble Codes

Result

Proceed to

C1241 is not output

A

C1241 is output

B

A

USE SIMULATION METHOD TO CHECK

B

REPLACE BRAKE ACTUATOR ASSEMBLY

    Speed Sensor Rotor Faulty (C1237)

    Master Cylinder Pressure Sensor (C1246)

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