Toyota Tacoma (2015-2018) Service Manual: Low Power Supply Voltage Malfunction (C1241)

Toyota Tacoma (2015-2018) Service Manual / Brake Control / Dynamic Control Systems / Vehicle Stability Control System(for Vacuum Brake Booster) / 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 deviates from the DTC detection condition due to a malfunction in the power supply or charging circuit such as the battery or generator circuit, etc.

The DTC is canceled 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: When vehicle speed is 3 km/h (2 mph) or more, +BS terminal voltage is continuously below 9.5 V for 10 seconds or more. When solenoid relay is on, +BS terminal voltage is below 9.5 V and relay contact is off for 0.22 seconds or more. When +BS terminal voltage is below 9.5 V, power supply voltage of vehicle speed sensor is continuously low for 60 seconds or more. When fail-safe motor relay is on and +BS terminal voltage is below 9.5 V, fail-safe motor relay overcurrent continues for 0.05 seconds or more.	ABS NO. 2 fuse Battery Charging system Wire harness or connector Skid control ECU (Brake actuator assembly)

HINT:

DTC will be output when conditions for any 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 zero point calibration and store system information (See page ).
Inspect the fuses for circuits related to this system before performing the following inspection procedure.

PROCEDURE

1.	INSPECT BATTERY

(a) Check the battery voltage.

Standard voltage:

11 to 14 V

CHECK OR REPLACE CHARGING SYSTEM OR BATTERY

2.	CHECK TERMINAL VOLTAGE (+BS TERMINAL)

(a) Turn the ignition switch off.

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

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
S1-38 (+BS) - Body ground	Always	11 to 14 V

Text in Illustration

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

REPAIR OR REPLACE HARNESS OR CONNECTOR (+BS CIRCUIT)

3.	CHECK HARNESS AND CONNECTOR (GND1 TERMINAL)

(a) Turn the ignition switch off.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
S1-25 (GND1) - Body ground	Always	Below 1 Ω

Text in Illustration

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

REPAIR OR REPLACE HARNESS OR CONNECTOR (GND1 CIRCUIT)

4.	RECONFIRM DTC

(a) Reconnect the S1 skid control ECU (brake actuator assembly) connector.

(b) Clear the DTC (See page (c) Turn the ignition switch off. ).

(d) Start the engine.

(e) Drive the vehicle at a speed of 20 km/h (12 mph) or more for 30 seconds or more.

(f) Check if the same DTC is recorded (See page HINT: HINT: ).

HINT:

If troubleshooting has been carried out according to the Problem Symptoms Table, refer back to the table and proceed to the next step (See page Result Result ).

Result

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

USE SIMULATION METHOD TO CHECK

REPLACE BRAKE ACTUATOR ASSEMBLY

Diagnostic Trouble Code Chart

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