Toyota Tundra Service Manual: Low Power Supply Voltage Malfunction (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 Power Supply Voltage Malfunction

Any of the following is detected:

  • The +BS terminal voltage is less than 8.3 V and the skid control ECU (brake actuator assembly) judge sthat power supply voltage is abnormal for 0.56 seconds or more.
  • When +BS terminal voltage is less than 8.3 V, power supply voltage of vehicle speed sensor is continuously low for 0.21 seconds or more.
  • ABS2 fuse
  • Battery
  • Charging system
  • Power source circuit
  • Ground circuit
  • Internal power supply circuit of the skid control ECU (brake actuator assembly)

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

Ignition 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 A57 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

A57-25 (+BS) - Body ground

Always

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 ignition 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

A57-38 (GND1) - Body ground

Always

Below 1 Ω

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (GND1 CIRCUIT)

OK

4.

RECONFIRM DTC

(a) Reconnect the A57 skid control ECU (brake actuator assembly) connector.

(b) Clear the DTCs.

Click here

(c) Turn the ignition switch off.

(d) Start the engine.

(e) Perform a road test.

(f) Check if the same DTC is output.

Click here

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)

    Acceleration Sensor Stuck Malfunction (C1243)

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