U0122, U0123, U0126, U0140, U0151, U0293, U1100, U1104

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DTC Code	DTC Name
U0122	Lost Communication with Vehicle Dynamics Control Module
U0123	Lost Communication with Yaw Rate Sensor Module
U0126	Lost Communication with Steering Angle Sensor Module
U0140	Lost Communication with Main Body ECU
U0151	Lost Communication with Airbag ECU
U0293	Lost Communication with HV ECU
U1100	Lost Communication with Seat Belt Control ECU
U1104	Lost Communication with Driving Support ECU

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DESCRIPTION

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

DTC No.	DTC Detection Condition	Trouble Area
U0122	When the power switch is on (IG), a communication error between the brake booster with master cylinder (skid control ECU) and the driving support ECU is detected for approx. 3 seconds. When the power switch is on (IG), a communication error between the skid control ECU assembly and the seat belt control ECU is detected for approx. 3 seconds.	Brake booster with master cylinder (skid control ECU) CAN communication system Driving support ECU Wire harness or connector
U0123	When the power switch is on (IG), a communication error between the yaw rate sensor and the driving support ECU is detected for approx. 1 second.	Yaw rate sensor CAN communication system Driving support ECU
U0126	When the power switch is on (IG), a communication error between the steering angle sensor and the driving support ECU is detected for approx. 1 second.	Steering angle sensor CAN communication system Driving support ECU
U0140	When the power switch is on (IG), communication stop between the main body ECU and seat belt control ECU continues for 6 seconds or more.	Main body ECU CAN communication system Seat belt control ECU Wire harness or connector
U0151	When the power switch is on (IG), communication stop between the center airbag sensor and seat belt control ECU continues for 6 seconds or more.	Center airbag sensor CAN communication system Seat belt control ECU Wire harness or connector
U0293	When the power switch is on (IG), a communication error between the power management control ECU and brake booster with master cylinder (skid control ECU) is detected for approx. 1 second. When the power switch is on (IG), a communication error between the power management control ECU and driving support ECU is detected for approx. 1 second.	Power management control ECU Brake booster with master cylinder (skid control ECU) CAN communication system Driving support ECU
U1100	When the power switch is on (IG), a communication error between the seat belt control ECU and the driving support ECU is detected for approx. 1 second.	Seat belt control ECU CAN communication system Driving support ECU
U1104	When the power switch is on (IG), a communication error between the driving support ECU and the millimeter wave radar sensor is detected for approx. 1 second. When the power switch is on (IG), a communication error between the driving support ECU and the power management control ECU is detected for approx. 1 second. When the power switch is on (IG), a communication error between the driving support ECU and seat belt control ECU is detected for approx. 1 second.	Communication circuit Millimeter wave radar sensor Driving support ECU CAN communication system Wire harness or connector

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WIRING DIAGRAM

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INSPECTION PROCEDURE

Note:

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

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PROCEDURE

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CHECK DTC OUTPUT

Connect the intelligent tester to the DLC3.
Turn the power switch on (IG).
Turn the intelligent tester on.
Enter the following menus: Body / Pre-Crash and Pre-Crash 2 / DTC.

Check for DTCs.

Result

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

AClick here
BClick here

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CHECK HARNESS AND CONNECTOR (DRIVING SUPPORT ECU - MILLIMETER WAVE RADAR SENSOR)

Disconnect the driving support ECU and millimeter wave radar sensor connectors.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
H5-38 (LRRD) - A2-4 (LRRD)	Always	Below 1 Ω
A2-4 (LRRD) - Body ground	Always	10 kΩ or higher
H5-38 (LRRD) - Body ground	Always	10 kΩ or higher

Reconnect the driving support ECU and millimeter wave radar sensor connectors.

OKClick here
NGClick here

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CHECK CAN COMMUNICATION SYSTEM
1. Clear the DTCs (Click here).
2. Recheck for DTCs.
  
  OK
  
  CAN communication system DTC is not output.
- OKClick here
- NGClick here

OK
CAN communication system DTC is not output.

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CHECK MILLIMETER WAVE RADAR SENSOR (IGB VOLTAGE)

Disconnect the millimeter wave radar sensor connector.
Turn the power switch on (IG).

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

Standard Voltage

Tester Connection	Condition	Specified Condition
A2-5 (IGB) - Body ground	Power switch on (IG)	11 to 14 V

Table 1. Text in Illustration
*a	Front view of wire harness connector (to Millimeter Wave Radar Sensor)

Reconnect the millimeter wave radar sensor connector.

OKClick here
NGClick here

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CHECK MILLIMETER WAVE RADAR SENSOR (SGND CIRCUIT)

Disconnect the millimeter wave radar sensor connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
A2-2 (SGND) - Body ground	Always	Below 1 Ω

Table 2. Text in Illustration
*a	Front view of wire harness connector (to Millimeter Wave Radar Sensor)

Reconnect the millimeter wave radar sensor connector.

OKClick here
NGClick here

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CHECK DRIVING SUPPORT ECU (LRRD OUTPUT VOLTAGE)

Turn the power switch on (IG).

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

Standard Voltage

Tester Connection	Condition	Specified Condition
H5-38 (LRRD) - Body ground	Power switch on (IG)	4.5 to 5.5 V

Table 3. Text in Illustration
*a	Component with harness connected (Driving Support ECU)

OKClick here
NGClick here

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REPLACE MILLIMETER WAVE RADAR SENSOR
1. Replace the millimeter wave radar sensor (Click here).
2. Adjust the millimeter wave radar sensor (Click here).
- NEXTClick here

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CHECK DTC OUTPUT

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	B

AClick here
BClick here

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GO TO CAN COMMUNICATION SYSTEMClick here
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REPAIR OR REPLACE HARNESS OR CONNECTOR (DRIVING SUPPORT ECU - MILLIMETER WAVE RADAR SENSOR)
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REPAIR OR REPLACE HARNESS OR CONNECTOR (IGB CIRCUIT)
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REPAIR OR REPLACE HARNESS OR CONNECTOR (SGND CIRCUIT)
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REPLACE DRIVING SUPPORT ECUClick here
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END

PRE-CRASH SAFETY SYSTEM, Diagnostic DTC:U0122, U0123, U0126, U0140, U0151, U0293, U1100, U1104