Last Modified: 04-05-2023 6.11:8.1.0 Doc ID: RM1000000018YBW
Model Year Start: 2018 Model: Sienna Prod Date Range: [11/2017 -           ]
Title: PRE-COLLISION: PRE-COLLISION SYSTEM: U1104; Lost Communication with Driving Support ECU; 2018 - 2020 MY Sienna [11/2017 -        ]

DTC

U1104

Lost Communication with Driving Support ECU

DESCRIPTION

The driving support ECU assembly is connected to the millimeter wave radar sensor assembly, forward recognition camera and skid control ECU (brake actuator assembly) via CAN communication. If communication with the millimeter wave radar sensor assembly, forward recognition camera or skid control ECU (brake actuator assembly) stops, the driving support ECU assembly stores DTC U1104.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

U1104

Lost Communication with Driving Support ECU

Any of the following conditions is met:

  • When the ignition switch is ON, a communication error between the driving support ECU assembly and the millimeter wave radar sensor assembly is detected for approximately 0.2 seconds.
  • When the ignition switch is ON, a communication error between the driving support ECU assembly and the forward recognition camera is detected for approximately 0.3 seconds.
  • When the ignition switch is ON, a communication error between the driving support ECU assembly and the skid control ECU (brake actuator assembly) is detected for approximately 1.5 seconds.
  • CAN communication system
  • Millimeter wave radar sensor assembly
  • Forward recognition camera
  • Skid control ECU (Brake actuator assembly)
  • Driving support ECU assembly
  • Wire harness or connector

CAUTION / NOTICE / HINT

NOTICE:

  • When replacing the driving support ECU assembly, always replace it with a new one. If a driving support ECU assembly which was installed to another vehicle is used, the information stored in the driving support ECU assembly will not match the information from the vehicle. As a result, a DTC may be stored.
  • When replacing the forward recognition camera, always replace it with a new one. If a forward recognition camera which was installed to another vehicle is used, the information stored in the forward recognition camera will not match the information from the vehicle. As a result, a DTC may be stored.
  • If the forward recognition camera has been replaced with a new one, be sure to perform forward recognition camera adjustment.

    Click here 2018 - 2020 MY Sienna [11/2017 -        ]; CRUISE CONTROL: FRONT CAMERA: ADJUSTMENT (SEQUENTIAL RECOGNITION)

  • When replacing the millimeter wave radar sensor assembly, always replace it with a new one. If a millimeter wave radar sensor assembly which was installed to another vehicle is used, the information stored in the millimeter wave radar sensor assembly will not match the information from the vehicle. As a result, a DTC may be stored.
  • When the millimeter wave radar sensor assembly is replaced with a new one, adjustment of the radar sensor beam axis must be performed.

    Click here 2018 - 2020 MY Sienna [11/2017 -        ]; CRUISE CONTROL: MILLIMETER WAVE RADAR SENSOR: ADJUSTMENT

  • Confirm that the connectors are securely connected, as a partially connected connector can cause this DTC to be stored.

PROCEDURE

1.

CHECK FOR DTCs (PRE-COLLISION SYSTEM)

(a) Check for DTCs.

Click here 2018 - 2020 MY Sienna [11/2017 -        ]; PRE-COLLISION: PRE-COLLISION SYSTEM: DTC CHECK / CLEAR

Result

Proceed to

DTC U1104 and other DTCs are output

A

Only DTC U1104 is output

B
A

GO TO DIAGNOSTIC TROUBLE CODE CHART

B

2.

CHECK FOR DTCs (FORWARD RECOGNITION CAMERA SYSTEM)

(a) Check for DTCs.

Click here 2018 - 2020 MY Sienna [11/2017 -        ]; CRUISE CONTROL: FORWARD RECOGNITION CAMERA SYSTEM: DTC CHECK / CLEAR

Result

Proceed to

Forward recognition camera system DTCs are not output

A

Forward recognition camera system DTCs are output

B
B

GO TO FORWARD RECOGNITION CAMERA SYSTEM

A

3.

CHECK FOR DTCs (VEHICLE STABILITY CONTROL SYSTEM)

(a) Check for DTCs.

Click here 2018 - 2020 MY Sienna [11/2017 -        ]; BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: VEHICLE STABILITY CONTROL SYSTEM: DTC CHECK / CLEAR

Result

Proceed to

Vehicle stability control system DTC are not output

A

Vehicle stability control system DTC are output

B
B

GO TO VEHICLE STABILITY CONTROL SYSTEM

A

4.

TEST MODE INSPECTION (VEHICLE STABILITY CONTROL SYSTEM)

HINT:

When entering test mode, the skid control ECU (brake actuator assembly) communicates with the driving support ECU assembly to judge whether the vehicle is equipped with the pre-collision system. Therefore, do not exit test mode within 5 seconds of entering test mode.

(a) Procedure to enter Test Mode

(1) Turn the ignition switch off.

(2) Check that the steering wheel is centered.

(3) Apply the parking brake.

(4) Check that the shift lever is in P.

(5) Connect the Techstream to the DLC3.

(6) Turn the ignition switch to ON.

(7) Turn the Techstream on.

(8) Switch the skid control ECU (brake actuator assembly) to Test Mode using the Techstream. Enter the following menus: Chassis / ABS/VSC/TRAC / Utility / Signal Check.

HINT:

Do not exit test mode within 5 seconds of entering test mode. If test mode is exited within 5 seconds of entering test mode, DTC U1104 may be stored. If DTC U1104 is output after exiting test mode, enter test mode again, wait at least 5 seconds, then recheck for DTCs.

(9) Check that the ABS warning and slip indicator lights come on for several seconds and then blink in the Test Mode pattern.

HINT:

If the ABS warning and slip indicator lights do not blink, inspect the ABS warning and slip indicator light circuits.

(b) End of Test Mode (Signal Check)

(1) End Test Mode (signal check) using the Techstream

  1. Turn the ignition switch off and enter normal mode.
  2. Remove the Techstream.
NEXT

5.

CHECK FOR DTCs (PRE-COLLISION SYSTEM)

(a) Clear the DTCs.

Click here 2018 - 2020 MY Sienna [11/2017 -        ]; PRE-COLLISION: PRE-COLLISION SYSTEM: DTC CHECK / CLEAR

(b) Perform the following procedure.

HINT:

If the following procedure is not performed, the previously output DTC cannot be detected.

  1. Turn the ignition switch to ON and wait 1.5 seconds or more.

(c) Check for DTCs.

Click here 2018 - 2020 MY Sienna [11/2017 -        ]; PRE-COLLISION: PRE-COLLISION SYSTEM: DTC CHECK / CLEAR

Result

Proceed to

DTC U1104 is not output

A

DTC U1104 is output

B
A

END
B

6.

REPLACE MILLIMETER WAVE RADAR SENSOR ASSEMBLY

(a) Replace the millimeter wave radar sensor assembly.

Click here 2018 - 2020 MY Sienna [11/2017 -        ]; CRUISE CONTROL: MILLIMETER WAVE RADAR SENSOR: REMOVAL

(b) Adjust the millimeter wave radar sensor assembly.

Click here 2018 - 2020 MY Sienna [11/2017 -        ]; CRUISE CONTROL: MILLIMETER WAVE RADAR SENSOR: ADJUSTMENT

NEXT

7.

CHECK FOR DTCs (PRE-COLLISION SYSTEM)

(a) Clear the DTCs.

Click here 2018 - 2020 MY Sienna [11/2017 -        ]; PRE-COLLISION: PRE-COLLISION SYSTEM: DTC CHECK / CLEAR

(b) Perform the following procedure.

HINT:

If the following procedure is not performed, the previously output DTC cannot be detected.

  1. Turn the ignition switch to ON and wait 1.5 seconds or more.

(c) Check for DTCs.

Click here 2018 - 2020 MY Sienna [11/2017 -        ]; PRE-COLLISION: PRE-COLLISION SYSTEM: DTC CHECK / CLEAR

Result

Proceed to

DTC U1104 is not output

A

DTC U1104 is output

B
A

END (MILLIMETER WAVE RADAR SENSOR ASSEMBLY WAS DEFECTIVE)
B

8.

REPLACE DRIVING SUPPORT ECU ASSEMBLY

(a) Replace the driving support ECU assembly.

Click here 2018 - 2020 MY Sienna [11/2017 -        ]; CRUISE CONTROL: DRIVING SUPPORT ECU: REMOVAL

NEXT

9.

CHECK FOR DTCs (PRE-COLLISION SYSTEM)

(a) Clear the DTCs.

Click here 2018 - 2020 MY Sienna [11/2017 -        ]; PRE-COLLISION: PRE-COLLISION SYSTEM: DTC CHECK / CLEAR

(b) Perform the following procedure.

HINT:

If the following procedure is not performed, the previously output DTC cannot be detected.

  1. Turn the ignition switch to ON and wait 1.5 seconds or more.

(c) Check for DTCs.

Click here 2018 - 2020 MY Sienna [11/2017 -        ]; PRE-COLLISION: PRE-COLLISION SYSTEM: DTC CHECK / CLEAR

Result

Proceed to

DTC U1104 is not output

A

DTC U1104 is output

B
A

END (DRIVING SUPPORT ECU ASSEMBLY WAS DEFECTIVE)
B

10.

REPLACE FORWARD RECOGNITION CAMERA

(a) Replace the forward recognition camera.

Click here 2018 - 2020 MY Sienna [11/2017 -        ]; CRUISE CONTROL: FRONT CAMERA: REMOVAL

(b) Perform forward recognition camera adjustment.

Click here 2018 - 2020 MY Sienna [11/2017 -        ]; CRUISE CONTROL: FRONT CAMERA: ADJUSTMENT (SEQUENTIAL RECOGNITION)

NEXT

11.

CHECK FOR DTCs (PRE-COLLISION SYSTEM)

(a) Clear the DTCs.

Click here 2018 - 2020 MY Sienna [11/2017 -        ]; PRE-COLLISION: PRE-COLLISION SYSTEM: DTC CHECK / CLEAR

(b) Perform the following procedure.

HINT:

If the following procedure is not performed, the previously output DTC cannot be detected.

  1. Turn the ignition switch to ON and wait 1.5 seconds or more.

(c) Check for DTCs.

Click here 2018 - 2020 MY Sienna [11/2017 -        ]; PRE-COLLISION: PRE-COLLISION SYSTEM: DTC CHECK / CLEAR

Result

Proceed to

DTC U1104 is not output

A

DTC U1104 is output

B
A

END (FORWARD RECOGNITION CAMERA WAS DEFECTIVE)
B

12.

REPLACE SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY)

(a) Replace the skid control ECU (brake actuator assembly).

Click here 2018 - 2020 MY Sienna [11/2017 -        ]; BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: BRAKE ACTUATOR: REMOVAL

NEXT

END (SKID CONTROL ECU WAS DEFECTIVE)