Toyota Prius: Front Side Radar Sensor System

Toyota Prius (XW60) 2023-2025 Service Manual / ADAS/AD / Advanced Driver Assistance System / Front Side Radar Sensor System

Precaution
Parts Location
System Diagram
How To Proceed With Troubleshooting
Utility
Problem Symptoms Table
Terminals Of Ecu
Freeze Frame Data
Fail-safe Chart
Data List / Active Test
Diagnostic Trouble Code Chart
VEHICLE CONTROL HISTORY (RoB)
Front Side Radar Sensor (Module "B") System Internal Failure (C1A1804)
Front Side Radar Sensor (Module "B") Beam Axis Misalignment (Horizontal) (C1A1900)
Lost Communication with Brake System Control Module "A" Missing Message (U012987,U013187,U029387)
Lost Communication with Cruise Control Front Distance Range Sensor Front Side "A" Missing Message (U123587)

Precaution

PRECAUTION

PRECAUTIONS FOR DISCONNECTING CABLE FROM NEGATIVE (-) AUXILIARY BATTERY TERMINAL

NOTICE:

After the ignition switch is turned off, there may be a waiting time before disconnecting the negative (-) auxiliary battery terminal.
Click here

HINT:

When disconnecting and reconnecting the auxiliary battery, there is an automatic learning function that completes learning when the respective system is used.

Click here

PRECAUTIONS FOR FRONT SIDE RADAR SENSOR SYSTEM

(a) The front side radar function may not detect Toyota Prius vehicles correctly in the following conditions:

(1) When the sensor is misaligned due to a strong impact to the sensor or its surrounding area.

(2) When mud, snow, ice, a sticker, etc. is covering the sensor or its surrounding area on the front bumper.

(3) When driving on a road surface that is wet with standing water during bad weather such as heavy rain, snow, or fog.

(4) When there is a significant difference in speed between this Toyota Prius vehicle and the vehicle that enters the detection area.

(5) When the difference in speed between this vehicle and another vehicle is changing.

(6) When a vehicle enters a detection area traveling at about the same speed as this vehicle.

(7) As your vehicle starts from a stop, a vehicle remains in the detection area.

(8) When driving up and down consecutive steep inclines, such as hills, dips in the road, etc.

(9) When driving on roads with sharp bends, consecutive curves, or uneven surfaces.

(10) When Toyota Prius vehicle lanes are wide, or when driving on the edge of a lane, and the vehicle in an adjacent lane is far away from this vehicle.

(11) When there is a significant difference in height between this vehicle and the vehicle that enters the detection area.

(12) Immediately after the pre-collision system is turned on.

(b) The front side radar function is not designed to detect the following types of Toyota Prius vehicles or objects:

*: Depending on conditions, detection of a vehicle and/or object may occur.

(1) Vehicles traveling from the opposite direction.

(2) Small motorcycles, bicycles, pedestrians, etc.*

(3) Following vehicles that are in the same lane.*

(4) Guardrails, walls, signs, parked Toyota Prius vehicles and similar stationary objects.*

(5) Vehicles driving 2 lanes across from this vehicle.*

(c) Instances of the front side radar function unnecessarily detecting a vehicle and/or object may increase under the following conditions:

(1) When the sensor is misaligned due to a strong impact to the sensor or its surrounding area.

(2) When a distance between this Toyota Prius vehicle and a guardrail, wall, etc. that enters the detection area is short.

(3) When driving up and down consecutive steep inclines, such as hills, dips in the road, etc.

(4) When vehicle lanes are narrow, or when driving on the edge of a lane, and a vehicle traveling in a lane other than the adjacent lanes enters the detection area.

(5) When driving on roads with sharp bends, consecutive curves, or uneven surfaces.

(6) When the tires are slipping or spinning.

(d) Under the following conditions, the front side radar system may store DTCs C1A1700 and C1A1900 by mistake:

(1) The Toyota Prius vehicle is driven continuously with the front side radar system on when using a drum tester such as a speedometer tester, brake/speedometer combination tester or chassis dynamometer.

(2) When mud, snow, ice, a sticker, etc. is covering the sensor or surrounding area on the front bumper.

HANDLING THE RADAR SENSOR

(a) Front side radar sensors are installed behind the left and right sides of the front bumper respectively. Observe the following to ensure the front side radar can function correctly.

(1) Keep the sensors and the surrounding areas on the front bumper clean at all times.

(2) Do not subject a sensor or its surrounding area on the front bumper to a strong impact. If a sensor is moved even slightly off position, the system may malfunction and Toyota Prius vehicles may not be detected correctly. In the following situations, inspect the sensor and surrounding area.

A sensor or its surrounding area is subject to a strong impact.
If the surrounding area of a sensor is scratched or dented, or part of them has become disconnected.

(3) Do not disassemble the sensor.

(4) Do not attach stickers to the sensor or surrounding area on the front bumper.

(5) Do not modify the sensor or surrounding area on the front bumper.

(6) Do not paint the front bumper any color other than an official Toyota color.

(7) Do not drop a sensor or subject it to a strong impact, as it is a high-precision device.

(8) Do not reuse a sensor that has been dropped or subjected to a strong impact.

REPLACEMENT PRECAUTIONS

(a) After replacing the front side radar sensor, make sure to perform ECU writing.

Click here

SENSOR EXPRESSIONS

(a) The descriptions for the front side radar sensor differ depending on the system. The expressions listed in the table below are used in this Repair Manual.

Part Name	Actual Part Name
Front side radar sensor (A)	Front side radar sensor (LH)
Front side radar sensor (B)	Front side radar sensor (RH)

Parts Location

PARTS LOCATION

ILLUSTRATION

*1	FRONT SIDE RADAR SENSOR (A)	*2	FRONT SIDE RADAR SENSOR (B)
*3	FORWARD RECOGNITION CAMERA	*4	ECM
*5	POWER STEERING ECU ASSEMBLY	*6	NO. 2 SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY)

ILLUSTRATION

HYBRID Toyota Prius Vehicle CONTROL ECU

DLC3

System Diagram

SYSTEM DIAGRAM

How To Proceed With Troubleshooting

CAUTION / NOTICE / HINT

HINT:

Use the following procedure to troubleshoot the front side radar sensor system.
*: Use the GTS.

PROCEDURE

1.	Toyota Prius Vehicle BROUGHT TO WORKSHOP

2.	CUSTOMER PROBLEM ANALYSIS

HINT:

If there are any scratches or impact marks on the rear bumper, perform the front side radar beam axis confirmation. If any abnormalities are found, perform the front side radar sensor installation condition inspection.

PRE-CHECK

(a) Measure the auxiliary battery voltage with the ignition switch off.

Standard voltage:

11 to 14 V

HINT:

If the voltage is below 11 V, recharge or replace the auxiliary battery before proceeding to the next step.

(b) Check the fuses and relays.

(c) Check the connector connections and terminals to make sure that there are no abnormalities such as loose connections, deformation, etc.

4.	CHECK COMMUNICATION FUNCTION OF CAN COMMUNICATION SYSTEM*

(a) Using the GTS, check for CAN communication system DTCs.

Click here

Result	Proceed to
CAN DTCs are not output	A
CAN DTCs are output	B

GO TO CAN COMMUNICATION SYSTEM

5.	CHECK FOR DTC AND FREEZE FRAME DATA*

(a) Using the GTS, check for DTCs.

Body Electrical > Front Side Radar "A" > Trouble Codes Body Electrical > Front Side Radar "B" > Trouble Codes

(1) Check for DTCs and save.

(2) Check for freeze frame data and save.

(3) Based on the saved DTCs and freeze frame data, simulate the malfunction conditions and check if the DTCs are output again.

Result	Proceed to
DTCs are not output (symptoms can be confirmed or reproduced)	A
DTCs are not output (symptoms cannot be confirmed or reproduced)	B
DTCs are output	C

USE SIMULATION METHOD TO CHECK

GO TO DTC CHART

6.	CHECK Toyota Prius Vehicle CONTROL HISTORY*

(a) Using the GTS, check for Vehicle Control History (RoB).

Body Electrical > Front Side Radar "A" > Utility

Tester Display
Toyota Prius Vehicle Control History (RoB)

Body Electrical > Front Side Radar "B" > Utility

Tester Display
Vehicle Control History (RoB)

(b) Make a note of the output Toyota Prius Vehicle Control History (RoB).

Result	Proceed to
Vehicle Control History (RoB) codes are not output	A
Toyota Prius Vehicle Control History (RoB) code is output	B

GO TO VEHICLE CONTROL HISTORY (RoB)

7.	PROBLEM SYMPTOMS TABLE

(a) Refer to Problem Symptoms Table.

Click here

Result	Proceed to
Fault is not listed in Problem Symptoms Table	A
Fault is listed in Problem Symptoms Table	B

GO TO PROBLEM SYMPTOMS TABLE

8.	PERFORM TROUBLESHOOTING BASED ON MALFUNCTION SYMPTOM*

(a) Refer to Terminals of ECU.

Click here

(b) Refer to Data List / Active Test.

Click here

9.	ADJUST, REPAIR OR REPLACE

Result	Proceed to
When adjusting or repairing	A
When replacing	B

GO TO STEP 11

10.

CLEAR DTC

(a) Clear the DTCs.

Body Electrical > Front Side Radar "A" > Clear DTCs Body Electrical > Front Side Radar "B" > Clear DTCs

GO TO STEP 12

11.	PERFORM BEAM AXIS CONFIRMATION

(a) Confirm the front side radar sensor beam axis display and perform the front side radar sensor beam axis adjustment.

Triangle Target: Click here

Driving Adjustment: Click here

ECU DATA SAVE/WRITE: Click here

12.	PERFORM CONFIRMATION TEST

END

Utility

UTILITY

Front Side Radar "A" Beam Axis Adjustment

HINT:

This utility procedure is used to perform beam axis alignment for the front side radar sensor (A).

(a) In accordance with the display of the GTS, perform "Front Side Radar "A" Beam Axis Adjustment".

Body Electrical > Front Side Radar "A" > Utility

Tester Display
Front Side Radar "A" Beam Axis Adjustment

HINT:

Refer to the adjustment procedure for the front side radar sensor system.

Click here

Front Side Radar "A" Beam Axis Display

HINT:

This utility procedure is used to display beam axis for the front side radar sensor (A).

(a) In accordance with the display of the GTS, perform "Front Side Radar "A" Beam Axis Display".

Body Electrical > Front Side Radar "A" > Utility

Tester Display
Front Side Radar "A" Beam Axis Display

Front Side Radar "A" ECU Data Save

HINT:

The beam axis alignment value can be saved to the GTS by performing a data save for the front side radar sensor (A).

(a) In accordance with the display of the GTS, perform "Front Side Radar "A" ECU Data Save".

Body Electrical > Front Side Radar "A" > Utility

Tester Display
Front Side Radar "A" ECU Data Save

Front Side Radar "A" ECU Data Write

HINT:

By writing the data to the front side radar sensor (A), the front side radar sensor (A) beam axis data from before the replacement can be written to a new front side radar sensor (A).

(a) In accordance with the display of the GTS, perform "Front Side Radar "A" ECU Data Write".

Body Electrical > Front Side Radar "A" > Utility

Tester Display
Front Side Radar "A" ECU Data Write

Transition to Online Axis Alignment Mode

HINT:

This utility procedure is used to perform transition to online axis alignment mode for front side radar sensor (A).

(a) This utility procedure is used to perform transition to online axis alignment mode for front side radar sensor (A).

Body Electrical > Front Side Radar "A" > Utility

Tester Display
Transition to Online Axis Alignment Mode

Front Side Radar "B" Beam Axis Adjustment

HINT:

This utility procedure is used to perform beam axis alignment for the front side radar sensor (B).

(a) In accordance with the display of the GTS, perform "Front Side Radar "B" Beam Axis Adjustment".

Body Electrical > Front Side Radar "B" > Utility

Tester Display
Front Side Radar "B" Beam Axis Adjustment

HINT:

Refer to the adjustment procedure for the front side radar sensor system.

Click here

Front Side Radar "B" Beam Axis Display

HINT:

This utility procedure is used to display beam axis for the front side radar sensor (B).

(a) In accordance with the display of the GTS, perform "Front Side Radar "B" Beam Axis Display".

Body Electrical > Front Side Radar "B" > Utility

Tester Display
Front Side Radar "B" Beam Axis Display

Front Side Radar "B" ECU Data Save

HINT:

The beam axis alignment value can be saved to the GTS by performing a data save for the front side radar sensor (B).

(a) In accordance with the display of the GTS, perform "Front Side Radar "B" ECU Data Save".

Body Electrical > Front Side Radar "B" > Utility

Tester Display
Front Side Radar "B" ECU Data Save

Front Side Radar "B" ECU Data Write

HINT:

By writing the data to the front side radar sensor (B), the front side radar sensor (B) beam axis data from before the replacement can be written to a new front side radar sensor (B).

(a) In accordance with the display of the GTS, perform "Front Side Radar "B" ECU Data Write".

Body Electrical > Front Side Radar "B" > Utility

Tester Display
Front Side Radar "B" ECU Data Write

HINT:

This utility procedure is used to perform transition to online axis alignment mode for front side radar sensor (B).

Transition to Online Axis Alignment Mode

(a) This utility procedure is used to perform transition to online axis alignment mode for front side radar sensor (B).

Body Electrical > Front Side Radar "B" > Utility

Tester Display
Transition to Online Axis Alignment Mode

Problem Symptoms Table

PROBLEM SYMPTOMS TABLE

HINT:

Use the table below to help determine the cause of problem symptoms. If multiple suspected areas are listed, the potential causes of the symptoms are listed in order of probability in the "Suspected Area" column of the table. Check each symptom by checking the suspected areas in the order they are listed. Replace parts as necessary.
Inspect the fuses and relays related to this system before inspecting the suspected areas below.

Front Side Radar Sensor System

Symptom	Suspected Area	Link
"System Stopped See Owner's Manual" is displayed	Toyota Prius Vehicle Control History
"System Malfunction Visit Your Dealer" is displayed	Vehicle Control History

Terminals Of Ecu

TERMINALS OF ECU

NOTICE:

DTCs may be output when connectors are disconnected during inspection. Therefore, be sure to clear the DTCs using the GTS once the inspection has been completed.
Do not apply excessive force to the front side radar sensor (A) connector.

FRONT SIDE RADAR SENSOR (A)

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

Terminal No. (Symbol)	Terminal Description	Condition	Specified Condition
A41-1 (FMGD) - Body ground	Ground	Always	Below 1 Ω
A41-2 (CA1N)	CAN communication signal	-	-
A41-3 (CA1P)	CAN communication signal	-	-
A41-5 (CA2P)	CAN communication signal	-	-
A41-6 (CA2N)	CAN communication signal	-	-
A41-8 (FMB) - A41-1 (FMGD)	Power source	Ignition switch off	Below 1 V
A41-8 (FMB) - A41-1 (FMGD)	Power source	Ignition switch ON	11 to 14 V

NOTICE:

DTCs may be output when connectors are disconnected during inspection. Therefore, be sure to clear the DTCs using the GTS once the inspection has been completed.
Do not apply excessive force to the front side radar sensor (B) connector.

FRONT SIDE RADAR SENSOR (B)

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

Terminal No. (Symbol)	Terminal Description	Condition	Specified Condition
A42-1 (FSGD) - Body ground	Ground	Always	Below 1 Ω
A42-2 (CA1N)	CAN communication signal	-	-
A42-3 (CA1P)	CAN communication signal	-	-
A42-5 (CA2P)	CAN communication signal	-	-
A42-6 (CA2N)	CAN communication signal	-	-
A42-8 (FSB) - A42-1 (FSGD)	Power source	Ignition switch off	Below 1 V
A42-8 (FSB) - A42-1 (FSGD)	Power source	Ignition switch ON	11 to 14 V

Freeze Frame Data

FREEZE FRAME DATA

DESCRIPTION

(a) Whenever a front side radar sensor system DTC is stored, the front side radar sensor stores the current vehicle state (ECU and sensor information) as Freeze Frame Data.

CHECK FREEZE FRAME DATA

(a) Select a DTC to display the freeze frame data.

Body Electrical > Front Side Radar "A" > Trouble Codes Body Electrical > Front Side Radar "B" > Trouble Codes

(b) Check the freeze frame data for the output DTC.

FREEZE FRAME DATA CHART

Body Electrical > Front Side Radar "A"

Tester Display	Measurement Item	Range	Normal Condition	Diagnostic Note
Total Distance Traveled	Driving distance value	0 to 16777215	-	-
Total Distance Traveled - Unit	Displays the driving distance unit	km or mile	-	-
Power Supply Voltage	Displays the supply power voltage value	0.00 to 49.95 V	-	-
Shift Position R	Displays the shift state R ON/OFF state	OFF or ON	OFF: Shift state R ON: Shift state other than R	-
Toyota Prius Vehicle Speed	Vehicle speed signal	-327.68 km/h (-204 mph) to 327.67 km/h (204 mph)	Approximately the same as actual vehicle speed	-
Steering Angle	Steering angle sensor	-3072.0 to 3070.5 deg	Steering wheel turned left: Value increases with steering wheel operation Steering wheel turned right: Value decreases with steering wheel operation	-
Yaw Rate	Displays the yaw rate sensor value	-125.000 to 124.612 deg/s	Turning right: -125.000 to 0 deg/s Turning left: 0 to 124.612 deg/s	-
Beam Axis Revision Angle	Displays the beam axis calibration angle	-327.68 to 327.67 deg	-	-

Body Electrical > Front Side Radar "B"

Tester Display	Measurement Item	Range	Normal Condition	Diagnostic Note
Total Distance Traveled	Driving distance value	0 to 16777215	-	-
Total Distance Traveled - Unit	Displays the driving distance unit	km or mile	-	-
Power Supply Voltage	Displays the supply power voltage value	0.00 to 49.95 V	-	-
Shift Position R	Displays the shift state R ON/OFF state	OFF or ON	OFF: Shift state R ON: Shift state other than R	-
Toyota Prius Vehicle Speed	Vehicle speed signal	-327.68 km/h (-204 mph) to 327.67 km/h (204 mph)	Approximately the same as actual vehicle speed	-
Steering Angle	Steering angle sensor	-3072.0 to 3070.5 deg	Steering wheel turned left: Value increases with steering wheel operation Steering wheel turned right: Value decreases with steering wheel operation	-
Yaw Rate	Displays the yaw rate sensor value	-125.000 to 124.612 deg/s	Turning right: -125.000 to 0 deg/s Turning left: 0 to 124.612 deg/s	-
Beam Axis Revision Angle	Displays the beam axis calibration angle	-327.68 to 327.67 deg	-	-

Fail-safe Chart

FAIL-SAFE CHART

FAIL-SAFE FUNCTION

(a) If a malfunction is detected in the front side radar sensor system, the systems that use the front side radar sensor perform the fail-safe function.

Data List / Active Test

DATA LIST / ACTIVE TEST

NOTICE:

In the table below, the values listed under "Normal Condition" are reference values. Do not depend solely on these reference values when deciding whether a part is faulty or not.

HINT:

Using the GTS to read the Data List allows the values or states of switches, sensors, actuators and other items to be read without removing any parts. This non-intrusive inspection can be very useful because intermittent conditions or signals may be discovered before parts or wiring is disturbed. Reading the Data List information early in troubleshooting is one way to save diagnostic time.

DATA LIST

(a) Read the Data List according to the display on the GTS.

Body Electrical > Front Side Radar "A" > Data List

Tester Display	Measurement Item	Range	Normal Condition	Diagnostic Note
Total Distance Traveled	Driving distance value	0 to 16777215	-	-
Total Distance Traveled - Unit	Displays the driving distance unit	km or mile	-	-
Power Supply Voltage	Displays the supply power voltage value	0.00 to 49.95 V	-	-
DRS System	Displays whether Toyota Prius vehicle is equipped with DRS	Without or With	Without: Not equipped with DRS With: Equipped with DRS	-
Shift Position R	Displays the shift state R ON/OFF state	OFF or ON	OFF: Shift state R ON: Shift state other than R	-
Toyota Prius Vehicle Speed	Vehicle speed signal	-327.68 km/h (-204 mph) to 327.67 km/h (204 mph)	Approximately the same as actual vehicle speed	-
Steering Angle	Steering angle sensor	-3072.0 to 3070.5 deg	Steering wheel turned left: Value increases with steering wheel operation Steering wheel turned right: Value decreases with steering wheel operation	-
Yaw Rate	Displays the yaw rate sensor value	-125.000 to 124.612 deg/s	Turning right: -125.000 to 0 deg/s Turning left: 0 to 124.612 deg/s	-
Axis Adjustment Error Code	Displays axis alignment error code	Normal or 0 to 15	Displays axis alignment error code	-
Software Write Status	Displays the status of whether software has been written	After Writing Software or Before Writing Software	After Writing Software: After software written Before Writing Software: Before software written	-
Power Steering Control Module "A" Malfunction	Displays whether there is a power steering system malfunction	No or Yes	No: Normal Yes: Malfunction detected	-
Yaw Rate Sensor Malfunction	Displays whether there is a yaw rate sensor malfunction	No or Yes	No: Normal Yes: Malfunction detected	-
Speed Sensor Malfunction	Displays whether there is a wheel speed sensor malfunction	No or Yes	No: Normal Yes: Malfunction detected	-
Front Side Radar Sensor Blockage	Displays whether the radar sensor is dirty	No or Yes	No: Normal Yes: Malfunction detected	-
Software Not Programmed	Malfunction is displayed if software has not been written	No or Yes	No: Normal Yes: Malfunction detected	-
Front Side Radar Sensor Blockage Level 2	Displays whether the radar sensor is dirty	No or Yes	No: Normal Yes: Malfunction detected	-
Front Side Radar Sensor Outside Guaranteed Operating Temperature	Displays whether the radar sensor has an abnormal temperature malfunction	No or Yes	No: Normal Yes: Malfunction detected	-
Front Side Radar Sensor Outside Guaranteed Operating Voltage	Displays whether the radar sensor has an abnormal voltage malfunction	No or Yes	No: Normal Yes: Malfunction detected	-
DRS System Malfunction	Displays whether there is a DRS system malfunction	No or Yes	No: Normal Yes: Malfunction detected	-
Beam Axis Revision Angle	Displays the beam axis calibration angle	-327.68 to 327.67 deg	-	-
Beam Axis Adjustment Completion Status	Displays the status of beam axis alignment completion	Incompleted or Completed	Incompleted: Beam axis alignment not completed Completed: Beam axis alignment completed	-
Destination Information	Displays whether the destination value has been defined	Defined or Undefined	Defined: Destination information has been defined Undefined: Destination information has not been defined	-
Dealer Radar Emission Stop Mode	Displays dealer radar emission stop mode status	OFF or ON	OFF: Dealer radar emission stop mode OFF ON: Dealer radar emission stop mode ON	-

Body Electrical > Front Side Radar "B" > Data List

Tester Display	Measurement Item	Range	Normal Condition	Diagnostic Note
Total Distance Traveled	Driving distance value	0 to 16777215	-	-
Total Distance Traveled - Unit	Displays the driving distance unit	km or mile	-	-
Power Supply Voltage	Displays the supply power voltage value	0.00 to 49.95 V	-	-
DRS System	Displays whether Toyota Prius vehicle is equipped with DRS	Without or With	Without: Not equipped with DRS With: Equipped with DRS	-
Shift Position R	Displays the shift state R ON/OFF state	OFF or ON	OFF: Shift state R ON: Shift state other than R	-
Toyota Prius Vehicle Speed	Vehicle speed signal	-327.68 km/h (-204 mph) to 327.67 km/h (204 mph)	Approximately the same as actual vehicle speed	-
Steering Angle	Steering angle sensor	-3072.0 to 3070.5 deg	Steering wheel turned left: Value increases with steering wheel operation Steering wheel turned right: Value decreases with steering wheel operation	-
Yaw Rate	Displays the yaw rate sensor value	-125.000 to 124.612 deg/s	Turning right: -125.000 to 0 deg/s Turning left: 0 to 124.612 deg/s	-
Axis Adjustment Error Code	Displays axis alignment error code	Normal or 0 to 15	Displays axis alignment error code	-
Software Write Status	Displays the status of whether software has been written	After Writing Software or Before Writing Software	After Writing Software: After software written Before Writing Software: Before software written	-
Front Side Radar Sensor Blockage	Displays whether the radar sensor is dirty	No or Yes	No: Normal Yes: Malfunction detected	-
Software Not Programmed	Malfunction is displayed if software has not been written	No or Yes	No: Normal Yes: Malfunction detected	-
Front Side Radar Sensor Blockage Level 2	Displays whether the radar sensor is dirty	No or Yes	No: Normal Yes: Malfunction detected	-
Front Side Radar Sensor Outside Guaranteed Operating Temperature	Displays whether the radar sensor has an abnormal temperature malfunction	No or Yes	No: Normal Yes: Malfunction detected	-
Front Side Radar Sensor Outside Guaranteed Operating Voltage	Displays whether the radar sensor has an abnormal voltage malfunction	No or Yes	No: Normal Yes: Malfunction detected	-
Beam Axis Revision Angle	Displays the beam axis calibration angle	-327.68 to 327.67 deg	-	-
Beam Axis Adjustment Completion Status	Displays the status of beam axis alignment completion	Incompleted or Completed	Incompleted: Beam axis alignment not completed Completed: Beam axis alignment completed	-
Destination Information	Displays whether the destination value has been defined	Defined or Undefined	Defined: Destination information has been defined Undefined: Destination information has not been defined	-
Dealer Radar Emission Stop Mode	Displays dealer radar emission stop mode	OFF or ON	OFF: Dealer radar emission stop mode OFF ON: Dealer radar emission stop mode ON	-

Diagnostic Trouble Code Chart

DIAGNOSTIC TROUBLE CODE CHART

Front Side Radar Sensor System

DTC No.	Detection Item	DTC Output from	Priority
C1A1604	Front Side Radar Sensor (Module "A") System Internal Failure	Front Side Radar "A"	A
C1A1700	Front Side Radar Sensor (Module "A") Beam Axis Misalignment (Horizontal)	Front Side Radar "A"	A
C1A1804	Front Side Radar Sensor (Module "B") System Internal Failure	Front Side Radar "B"	A
C1A1900	Front Side Radar Sensor (Module "B") Beam Axis Misalignment (Horizontal)	Front Side Radar "B"	A
U012987	Lost Communication with Brake System Control Module "A" Missing Message	Front Side Radar "A"	B
U013187	Lost Communication with Power Steering Control Module "A" Missing Message	Front Side Radar "A"	B
U029387	Lost Communication with Hybrid/EV Powertrain Control Module Missing Message	Front Side Radar "A"	B
U123587	Lost Communication with Cruise Control Front Distance Range Sensor Front Side "A" Missing Message	Front Side Radar "B"	A
U123687	Lost Communication with Cruise Control Front Distance Range Sensor Front Side "B" Missing Message	Front Side Radar "A"	A

VEHICLE CONTROL HISTORY (RoB)

VEHICLE CONTROL HISTORY (RoB)

NOTICE:

Vehicle control history may be recorded due to the replacement or repair of related parts.
When checking the Vehicle Control History, make sure to record the output codes. Then, clear the Vehicle Control History (RoB) and check it again.

CHECK Toyota Prius Vehicle CONTROL HISTORY (FRONT SIDE RADAR SENSOR SYSTEM)

(a) Read the Vehicle Control History (RoB) according to the display on the GTS.

Body Electrical > Front Side Radar "A" > Utility

Tester Display
Toyota Prius Vehicle Control History (RoB)

Body Electrical > Front Side Radar "B" > Utility

Tester Display
Vehicle Control History (RoB)

Toyota Prius Vehicle Control History (RoB) (Front Side Radar "A")

Code	Tester Display	Description	Diagnostic Note
X2000	Yaw Rate Sensor Malfunction	History of yaw rate sensor malfunction signal output from the yaw rate sensor being received	Refer to Electronically Controlled Brake System.
X2001	Steering Angle Sensor Malfunction	History of steering sensor malfunction signal output from the No. 2 skid control ECU (brake actuator assembly) being received	Refer to Electronically Controlled Brake System.
X2004	Speed Sensor Malfunction	History of Toyota Prius vehicle speed sensor malfunction signal output from the No. 2 skid control ECU (brake actuator assembly) being received	Refer to Electronically Controlled Brake System.
X208E	Power Steering Control Module "A" Malfunction	Power steering system malfunction judgment result is output	Refer to Power Steering System.
X217C	Front Side Radar Sensor (Module "A") Outside Guaranteed Operating Temperature	Front side radar sensor (A) ambient temperature was outside of guaranteed operating range	-
X217D	Front Side Radar Sensor (Module "A") Outside Guaranteed Operating Voltage	Front side radar sensor (A) voltage was outside of guaranteed operating range	-
X217E	Front Side Radar Sensor (Module "A") Blockage	Detection range decreased due to dirty bumper surface	Clean away any stickers or foreign matter (dirt, debris, snow, etc.)
X217F	Front Side Radar Sensor (Module "A") Blockage Level 2	Detection range decreased due to dirty bumper surface	Clean away any stickers or foreign matter (dirt, debris, snow, etc.)
XF021	Software Not Programmed	Partial software is not written

Toyota Prius Vehicle Control History (RoB) (Front Side Radar "B")

Code	Tester Display	Description	Diagnostic Note
X2180	Front Side Radar Sensor (Module "B") Outside Guaranteed Operating Temperature	Front side radar sensor (B) ambient temperature was outside of guaranteed operating range	-
X2181	Front Side Radar Sensor (Module "B") Outside Guaranteed Operating Voltage	Front side radar sensor (B) voltage was outside of guaranteed operating range	-
X2182	Front Side Radar Sensor (Module "B") Blockage	Detection range decreased due to dirty bumper surface	Clean away any stickers or foreign matter (dirt, debris, snow, etc.)
X2183	Front Side Radar Sensor (Module "B") Blockage Level 2	Detection range decreased due to dirty bumper surface	Clean away any stickers or foreign matter (dirt, debris, snow, etc.)
XF021	Software Not Programmed	Partial software is not written

CLEAR Toyota Prius Vehicle CONTROL HISTORY (FRONT SIDE RADAR SENSOR SYSTEM)

NOTICE:

By performing this procedure, all stored Vehicle Control History will be cleared.

(a) According to the display on the GTS, clear the Vehicle Control History (RoB).

Body Electrical > Front Side Radar "A" > Utility

Tester Display
Toyota Prius Vehicle Control History (RoB)

Body Electrical > Front Side Radar "B" > Utility

Tester Display
Vehicle Control History (RoB)

CHECK Toyota Prius Vehicle CONTROL HISTORY (AIRBAG SYSTEM)

(a) Part of the control history can be confirmed using the Vehicle Control History.

Click here

Front Side Radar Sensor (Module "B") System Internal Failure (C1A1804)

DESCRIPTION

This DTC is stored when the front side radar sensor (B) detects an internal malfunction.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	DTC Output from	Priority
C1A1804	Front Side Radar Sensor (Module "B") System Internal Failure	A front side radar sensor (B) internal malfunction is detected.	Front side radar sensor (B)	Front Side Radar "B"	A

CAUTION / NOTICE / HINT

NOTICE:

When checking for DTCs, make sure that the pre-collision system is turned on.
After replacing the front side radar sensor, make sure to perform ECU writing.
Click here
After replacing the front side radar sensor, make sure to perform front side radar sensor beam axis alignment and clear all stored Toyota Prius vehicle control history of each system.
HINT:

Front side radar sensor beam axis alignment can be performed by using "Triangle Target", "Driving Adjustment" or "ECU DATA SAVE/WRITE".

Triangle Target:

Driving Adjustment:

ECU DATA SAVE/WRITE:

PROCEDURE

1.	REPLACE FRONT SIDE RADAR SENSOR (B)

HINT:

Click here

END

Front Side Radar Sensor (Module "B") Beam Axis Misalignment (Horizontal) (C1A1900)

DESCRIPTION

This DTC is stored when the angle of the front side radar sensor (B) deviates more than the allowable range from the horizontal axis.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	DTC Output from	Priority
C1A1900	Front Side Radar Sensor (Module "B") Beam Axis Misalignment (Horizontal)	When the front side radar sensor system is operating, the angle of the front side radar sensor (B) has deviated 6° or more from the horizontal axis.	Front side radar sensor (B)	Front Side Radar "B"	A

CAUTION / NOTICE / HINT

NOTICE:

When checking for DTCs, make sure that the pre-collision system is turned on.
After replacing the front side radar sensor, make sure to perform ECU writing.
Click here
If the bumper is damaged or the Toyota Prius vehicle has a history of body repair, there is a possibility that the installation area of the front side radar sensor may be deformed and the front side radar sensor system may not operate correctly, so visually inspect the front side radar sensor installation area (frame, stud bolt) to make sure it is not dented or bent.
If the visual inspection finds a problem, check the installation condition of the front side radar sensor, and adjust the installation position of the front side radar sensor as necessary.

Click here
After replacing the front side radar sensor, make sure to perform front side radar sensor beam axis alignment and clear all stored Toyota Prius vehicle control history of each system.
HINT:

Front side radar sensor beam axis alignment can be performed by using "Triangle Target", "Driving Adjustment" or "ECU DATA SAVE/WRITE".

Triangle Target:

Driving Adjustment:

ECU DATA SAVE/WRITE:

HINT:

If a drum tester such as a speedometer tester, brake/speedometer combination tester or chassis dynamometer is used with the pre-collision system on, the front side radar sensor may store this DTC by mistake.
When mud, snow, ice, a sticker, etc. is covering the sensor or its surrounding area on the front bumper, the front side radar sensor may store this DTC by mistake.

PROCEDURE

1.	ADJUST FRONT SIDE RADAR SENSOR (B)

HINT:

Triangle Target:

Driving Adjustment:

ECU DATA SAVE/WRITE:

2.	CHECK FOR DTCs

(a) Check for DTCs.

Body Electrical > Front Side Radar "B" > Trouble Codes

Result	Proceed to
C1A1900 is not output	A
C1A1900 is output	B

END

REPLACE FRONT SIDE RADAR SENSOR (B)

Lost Communication with Brake System Control Module "A" Missing Message (U012987,U013187,U029387)

DESCRIPTION

The object recognition camera communicates with each sensor and ECU via CAN communication.

If any malfunction is detected in a CAN communication circuit, one or more CAN communication system DTCs are stored.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	DTC Output from	Priority
U012987	Lost Communication with Brake System Control Module "A" Missing Message	After 3 seconds or more have elapsed since the ignition switch was turned to ON (IG), there is a communication malfunction between the front side radar sensor (A) and No. 2 skid control ECU (brake actuator sub-assembly) for approximately 5 seconds or more.	CAN communication system	Front Side Radar "A"	B
U013187	Lost Communication with Power Steering Control Module "A" Missing Message	After 3 seconds or more have elapsed since the ignition switch was turned to ON (IG), there is a communication malfunction between the front side radar sensor (A) and power steering ECU assembly for approximately 4 seconds or more.	CAN communication system	Front Side Radar "A"	B
U029387	Lost Communication with Hybrid/EV Powertrain Control Module Missing Message	When the Toyota Prius vehicle speed is 5 km/h or more and 3 seconds or more have elapsed since the ignition switch was turned to ON (IG), there is a communication malfunction between the front side radar sensor (A) and hybrid vehicle control ECU for 11 seconds or more.	CAN communication system	Front Side Radar "A"	B

PROCEDURE

1.	CHECK FOR DTCs

(a) Check for DTCs.

HINT:

If the detection conditions are not met, the system cannot detect the malfunction.

Body Electrical > Front Side Radar "A" > Trouble Codes

Result	Proceed to
DTCs are not output	A
U012987, U013187 or U029387 is output	B

USE SIMULATION METHOD TO CHECK

GO TO CAN COMMUNICATION SYSTEM

Lost Communication with Cruise Control Front Distance Range Sensor Front Side "A" Missing Message (U123587)

DESCRIPTION

When the front side radar sensor (B) judges that there is a communication malfunction with the front side radar sensor (A), this DTC is stored.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	DTC Output from	Priority
U123587	Lost Communication with Cruise Control Front Distance Range Sensor Front Side "A" Missing Message	The front side radar sensor (B) does not receive communication from the front side radar sensor (A)	Front side radar sensor (A) Front side radar sensor (B)	Front Side Radar "B"	A

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

When checking for DTCs, make sure that the pre-collision system is turned on.
After replacing the front side radar sensor, make sure to perform ECU writing.
Click here
After replacing the front side radar sensor, make sure to perform front side radar sensor beam axis alignment and clear all stored Toyota Prius vehicle control history of each system.
HINT:

Front side radar sensor beam axis alignment can be performed by using "Triangle Target", "Driving Adjustment" or "ECU DATA SAVE/WRITE".

Triangle Target:

Driving Adjustment:

ECU DATA SAVE/WRITE:

HINT:

Before disconnecting each connector for inspection, push in on the connector case to check that each connector is not loose or disconnected.
When a connector is disconnected, check that the terminals and connector case are not cracked, deformed or corroded.
If a DTC is stored again after being cleared, the malfunction may be occurring due to vibration of the Toyota Prius vehicle. In this case, wiggle an ECU or wire harness to check if a malfunction occurs.

PROCEDURE