Toyota Tundra Service Manual: Power Supply Voltage Circuit (C1241)

Toyota Tundra Service Manual / Brake / Brake Control / Dynamic Control Systems / Trailer Brake Control System / Power Supply Voltage Circuit (C1241)

DESCRIPTION

If a malfunction is detected in the power supply circuit, the trailer brake control ECU (brake control with bracket relay) stores this DTC.

DTC No.

Detection Item

INF Code

DTC Detection Condition

Trouble Area

C1241

Power Supply Voltage Circuit

INF Code: 81 (Low power supply voltage malfaunction)
- At a vehicle speed of 3 km/h or higher, the IG terminal voltage is continuously below 7.9 V for 5 seconds or more
INF Code: 82 (High power supply voltage malfaunction)
- The IG terminal voltage continuously exceeds 17.8 V for 5 seconds or more with the ignition switch on

Trailer brake control ECU (Brake control with bracket relay)
Harness or connector
ECU-IG1 NO.2 fuse

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

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

CHECK OR REPLACE CHARGING SYSTEM COMPONENT OR BATTERY

2.	CHECK TERMINAL VOLTAGE (IG TERMINAL)

(a) Turn the ignition switch off.

*a	Front view of wire harness connector (to Trailer Brake Control ECU (Brake Control with Bracket Relay))

(b) Disconnect the J172 trailer brake control ECU (brake control with bracket relay) 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
J172-13 (IG) - Body ground	Ignition switch ON	11 to 14 V

REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)

3.	CHECK HARNESS AND CONNECTOR (GND TERMINAL)

(a) Turn the ignition switch off.

*a	Front view of wire harness connector (to Trailer Brake Control ECU (Brake Control with Bracket Relay))

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
J172-20 (GND) - Body ground	Always	Below 1 Ω

REPAIR OR REPLACE HARNESS OR CONNECTOR (GND CIRCUIT)

4.	RECONFIRM DTC

(a) Reconnect the J172 trailer brake control ECU (brake control with bracket relay) connector.

(b) Clear the DTCs.

Click here

(d) Turn the ignition switch to ON.

(e) Perform a road test.

(f) Check if the same DTC is output.

Click here

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

USE SIMULATION METHOD TO CHECK

REPLACE BRAKE CONTROL WITH BRACKET RELAY

ECU Malfunction (C14A7)

Acceleration Sensor Output Malfunction (C1245)

See More:

Toyota Tundra Owners Manual > Steps to take in an emergency: If you think something is wrong
If you notice any of the following symptoms, your vehicle probably needs adjustment or repair. Contact your Toyota dealer as soon as possible. Visible symptoms Fluid leaks under the vehicle. (Water dripping from the air conditioning after use is normal.) Flat-looking tires or uneven tire wear Engin ...