DTC U1104: Lost Communication with Driving Support ECU [08/2019 - ]: Procedure

1. Check for DTCs.

   Refer to DTC CHECK / CLEAR [08/2019 - ]

   Result

   Result	Proceed to
   DTCs are not output	A
   DTC U0235 is output	B
   DTC U0235 and U1104 are output	C
   DTC U1104 is output	D

Result: 

B 

See step  6

Result: 

C 

See step  7

Result: 

D 

REPLACE DRIVING SUPPORT ECU ASSEMBLY. Refer to  REMOVAL [08/2019 - ] 

Result: 

A 

See step  2

1. Connect the Techstream to the DLC3.
2. Turn the engine switch on (IG).
3. Turn the Techstream on.
4. Enter the following menus: System Select / Can Bus Check.

   Refer to DIAGNOSIS SYSTEM [08/2019 - 08/2020] , or refer to DIAGNOSIS SYSTEM [08/2020 - 08/2021] , or refer to DIAGNOSIS SYSTEM [08/2021 - ]

   Result

   Result	Proceed to
   All of the ECUs and sensors that are currently connected to the CAN communication system are displayed	A
   None of the ECUs and sensors that are currently connected to the CAN communication system are displayed, or some of them are not displayed	B

Result: 

B 

GO TO CAN COMMUNICATION SYSTEM. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [08/2019 - ] 

Result: 

A 

See step  3

1. Check for DTCs.

   Refer to DTC CHECK / CLEAR [08/2019 - ]

   HINT: 

   Pre-collision system DTC U1104 may be stored due to a malfunction in the vehicle stability control system. Therefore it is necessary to check for and troubleshoot vehicle stability control system DTCs first.

   Result

   Result	Proceed to
   Vehicle stability control system DTC are not output	A
   Vehicle stability control system DTC are output	B

Result: 

B 

GO TO VEHICLE STABILITY CONTROL SYSTEM. Refer to  DIAGNOSTIC TROUBLE CODE CHART [08/2019 - 08/2021]  , or refer to  DIAGNOSTIC TROUBLE CODE CHART [08/2021 - ] 

Result: 

A 

See step  4

HINT: 

When entering test mode, the skid control ECU (master cylinder solenoid) 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.

1. Procedure to Enter Test Mode (Signal Check)
   1. Turn the engine switch on (IG).
   2. Change the shift state to park (P).
   3. Check that the steering wheel is centered.
   4. Turn the engine switch off.
   5. Connect the Techstream to the DLC3.
   6. Turn the engine switch on (IG).
   7. Check that the parking brake is released.
   8. Turn the Techstream on.
   9. Switch the skid control ECU (master cylinder solenoid) to Test Mode (Signal Check) using the Techstream.
   10. Enter the following menus: Chassis / ABS/VSC/TRC / 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.

2. Test Mode (Signal Check) Display Check
   1. 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 light or slip indicator light remains illuminated or does not illuminate when Test Mode (Signal Check) is entered, a component or wire harness may be malfunctioning.

3. End of Test Mode (Signal Check)
   1. Turn the engine switch off and disconnect the Techstream.

   Result

   Proceed to
   NEXT

Result: 

NEXT 

See step  5

1. Clear the DTCs.

   Refer to DTC CHECK / CLEAR [08/2019 - ]

2. Make sure that the DTC detection conditions are met.

   HINT: 

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

3. Check for DTCs.

   Refer to DTC CHECK / CLEAR [08/2019 - ]

   Result

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

Result: 

A 

END 

Result: 

B 

REPLACE DRIVING SUPPORT ECU ASSEMBLY. Refer to  REMOVAL [08/2019 - ] 

1. Replace the millimeter wave radar sensor assembly.

   Refer to REMOVAL [08/2019 - ]

2. Perform millimeter wave radar sensor assembly adjustment.

   Refer to ADJUSTMENT [08/2019 - ]

   Result

   Proceed to
   NEXT

Result: 

NEXT 

END 

1. Replace the forward recognition camera.

   Refer to REMOVAL [08/2019 - ]

2. Perform Forward Recognition Camera Learning.

   Refer to ADJUSTMENT (SEQUENTIAL RECOGNITION) [08/2019 - ]

   Result

   Proceed to
   NEXT

Result: 

NEXT 

END