PRE-CRASH SAFETY SYSTEM, Diagnostic DTC:U0125, U0126, U0129, U0140, U0142, U0151, U0235, U1002, U1100, U1104

DTC Code	DTC Name
U0125	Lost Communication with Yaw Rate Sensor Module
U0126	Lost Communication with Steering Angle Sensor Module
U0129	Lost Communication with Brake System Control Module
U0140	Lost Communication with J/B ECU
U0142	Lost Communication with Body Control Module "B"
U0151	Lost Communication with Airbag ECU
U0235	Lost Communication with Cruise Control Front Distance Range Sensor
U1002	Lost Communication with Gateway Module
U1100	Lost Communication with Seat Belt Control ECU
U1104	Lost Communication with Driving Support ECU

DESCRIPTION

The driving support ECU assembly uses the millimeter wave radar sensor assembly to detect obstacles in front of the vehicle. Based on this information, the driving support ECU assembly sends pre-crash control operation signals. These DTCs are stored when a communication malfunction occurs between the sensors and ECUs that detect crashes, or between ECUs that perform the pre-crash control.

The driving support ECU assembly sends vehicle speed and vehicle condition information to the millimeter wave radar sensor assembly. The millimeter wave radar sensor assembly then sends information on the presence, distance, and relative speed of objects ahead to the driving support ECU assembly. The driving support ECU assembly sends this information to the ECM and performs pre-crash safety system operation (DTC U1104).

DTC No.	DTC Detection Condition	Trouble Area
U0125	When the engine switch is on (IG), a communication error between the airbag sensor assembly (yaw rate sensor) and the driving support ECU is detected for approximately 1 second.	Airbag sensor assembly (yaw rate sensor) CAN communication system Driving support ECU assembly Wire harness or connector
U0126	When the engine switch is on (IG), a communication error between the steering angle sensor and the driving support ECU assembly is detected for approximately 4 seconds.	CAN communication system Steering angle sensor Driving support ECU assembly Wire harness or connector
U0129	When the engine switch is on (IG), a communication error between the brake actuator assembly (skid control ECU) and the driving support ECU is detected for approximately 3 second. When the engine switch is on (IG), a communication error between the brake actuator assembly (skid control ECU) and the seat belt control ECU is detected for approximately 3 seconds.	Brake actuator assembly (skid control ECU) CAN communication system Seat belt control ECU Driving support ECU assembly Wire harness or connector
U0140	When the engine switch is on (IG), a communication error between the main body ECU and seat belt control ECU is detected for approximately 6 second.	CAN communication system Main body ECU (multiplex network body ECU) Seat belt control ECU Wire harness or connector
U0142	When the engine switch is on (IG), a communication error between the main body ECU and driving support ECU assembly is detected for approximately 14.2 seconds or more.	CAN communication system Main body ECU (multiplex network body ECU) Driving support ECU assembly Wire harness or connector
U0151	When the engine switch is on (IG), a communication error between the airbag sensor assembly and seat belt control ECU is detected for approximately 6 second.	CAN communication system Airbag sensor assembly Seat belt control ECU Wire harness or connector
U0235	When the engine switch is on (IG), a communication error between the millimeter wave radar sensor assembly and the driving support ECU assembly is detected for approximately 1 seconds.	CAN communication system Millimeter wave radar sensor assembly Driving support ECU assembly Wire harness or connector
U1002	When the engine switch is on (IG), a communication error between the millimeter wave radar sensor assembly and driving support ECU is detected for approximately 2 second.	Millimeter wave radar sensor assembly CAN communication system Driving support ECU assembly Wire harness or connector
U1100	When the engine switch is on (IG), a communication error between the seat belt control ECU and the driving support ECU assembly is detected for approximately 10 seconds.	CAN communication system Driving support ECU assembly Seat belt control ECU Wire harness or connector
U1104	When the engine switch is on (IG), a communication error between the driving support ECU assembly and the millimeter wave radar sensor assembly is detected for approximately 1 second. When the engine switch is on (IG), a communication error between the driving support ECU assembly and the network gateway ECU is detected for approximately 1 second. When the engine switch is on (IG), a communication error between the driving support ECU assembly and the seat belt control ECU is detected for approximately 1 second.	CAN communication system Millimeter wave radar sensor assembly Driving support ECU assembly Seat belt control ECU Wire harness or connector Network gateway ECU

WIRING DIAGRAM

INSPECTION PROCEDURE

Note

When replacing the millimeter wave radar sensor assembly with a new one, make sure to perform Adjust Millimeter Wave Radar Sensor Assembly Click here.
Confirm that the connectors are securely connected, as a partially connected connector is suspected for the cause of these DTCs.

PROCEDURE

CHECK DTC OUTPUT

Connect the GTS to the DLC3.
Turn the engine switch on (IG).
Turn the GTS on.
Enter the following menus: Body Electrical / Pre-Crash and Pre-Crash 2 / Trouble Codes.

Check for DTCs.

Result

Result	Proceed to
DTC U1104 is output	A
DTC U1104 is not output	B

GO TO CAN COMMUNICATION SYSTEM Click here

CHECK CAN COMMUNICATION SYSTEM
1. Select "CAN Bus Check" from the "System Selection Menu" on the GTS.
2. Select "Communication Malfunction Check" from the "CAN Bus Check" screen, and then select "OK".
  
  OK
  
  CAN communication is normal.
NG
GO TO CAN COMMUNICATION SYSTEM Click here

OK

OK
CAN communication is normal.

CHECK MILLIMETER WAVE RADAR SENSOR ASSEMBLY (IGB CIRCUIT)

Disconnect the A55 millimeter wave radar sensor assembly connector.
Turn the engine switch on (IG).

Text in Illustration
*a	Front view of wire harness connector (to Millimeter Wave radar sensor assembly)

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

Standard Voltage

Tester Connection	Condition	Specified Condition
A55-5 (IGB) - Body ground	Engine switch on (IG)	11 to 14 V

REPAIR OR REPLACE HARNESS OR CONNECTOR (IGB CIRCUIT)

CHECK HARNESS AND CONNECTOR (MILLIMETER WAVE RADAR SENSOR ASSEMBLY - BODY GROUND)

Disconnect the A55 millimeter wave radar sensor assembly connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
A55-2 (SGND) - Body ground	Always	Below 1 Ω

REPAIR OR REPLACE HARNESS OR CONNECTOR

REPLACE MILLIMETER WAVE RADAR SENSOR ASSEMBLY
1. Replace the millimeter wave radar sensor assembly Click here.
2. Adjust the millimeter wave radar sensor assembly Click here.
NEXT

CHECK DTC OUTPUT

Connect the GTS to the DLC3.
Turn the engine switch on (IG).
Turn the GTS on.
Clear the DTCs Click here.
Turn the cruise control main switch on.
Drive the vehicle at the required speed (45 km/h (28 mph) or higher).

Check if the same DTC is output Click here.

Result

Result	Proceed to
DTC U1104 is not output.	A
DTC U1104 is output (for LHD).	B
DTC U1104 is output (for RHD).	B

REPLACE DRIVING SUPPORT ECU ASSEMBLY Click here

END (MILLIMETER WAVE RADAR SENSOR ASSEMBLY WAS DEFECTIVE)