DTC U1104: Lost Communication with Driving Support ECU [11/2015 - 12/2018]: Procedure

1. Check for DTCs.

   Body Electrical > Pre-Collision 2 > Trouble Codes 

   Result

   Result	Proceed to
   U1104 and other DTCs are output	A
   Only U1104 is output	B

Result: 

A 

GO TO DIAGNOSTIC TROUBLE CODE CHART. Refer to  DIAGNOSTIC TROUBLE CODE CHART [11/2015 - 12/2018] 

Result: 

B 

See step  2

1. Check for DTCs.

   Chassis > Front Recognition Camera > Trouble Codes 

   Result

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

Result: 

B 

GO TO FORWARD RECOGNITION CAMERA SYSTEM. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [11/2015 - 07/2020] 

Result: 

A 

See step  3

1. Check for DTCs.

   Chassis > ABS/VSC/TRAC > Trouble Codes 

   Result

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

Result: 

B 

GO TO ELECTRONICALLY CONTROLLED BRAKE SYSTEM. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [11/2015 - 12/2018] 

Result: 

A 

See step  4

HINT: 

When entering test mode, the skid control ECU (brake booster with master cylinder 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.

1. Procedure to Enter Test Mode (Signal Check)
   1. Turn the power switch off.
   2. Check that the steering wheel is centered.
   3. Check that park (P) is selected.
   4. Connect the Techstream to the DLC3.
   5. Turn the power switch on (IG).
   6. Turn the Techstream on.
   7. Switch the skid control ECU (brake booster with master cylinder assembly) to Test Mode (Signal Check) 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.

      Chassis > ABS/VSC/TRAC > Utility 

      Tester Display
      Signal Check

2. Test Mode (Signal Check) Display Check
   1. Check that the ABS warning, brake warning / yellow (minor malfunction) and slip indicator lights come on for several seconds and then blink in the Test Mode pattern.

      HINT: 

      If the ABS warning light, brake warning light / yellow (minor malfunction) 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 power switch off and disconnect the Techstream.

   Result

   Proceed to
   NEXT

Result: 

NEXT 

See step  5

1. Clear the DTCs.

   Body Electrical > Pre-Collision 2 > Clear DTCs 

   Result

   Proceed to
   NEXT

Result: 

NEXT 

See step  6

1. Perform the following procedure.

   HINT: 

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

   1. Turn the power switch on (IG) and wait 1.5 seconds or more.
2. Check for DTCs.

   Body Electrical > Pre-Collision 2 > Trouble Codes 

   Result

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

Result: 

A 

END 

Result: 

B 

See step  7

1. Replace the millimeter wave radar sensor assembly.

   HINT: 

   Refer to REMOVAL [11/2015 - 07/2020]

2. Adjust the millimeter wave radar sensor assembly.

   HINT: 

   Refer to ADJUSTMENT [11/2015 - 12/2018]

   Result

   Proceed to
   NEXT

Result: 

NEXT 

See step  8

1. Clear the DTCs.

   Body Electrical > Pre-Collision 2 > Clear DTCs 

   Result

   Proceed to
   NEXT

Result: 

NEXT 

See step  9

1. Perform the following procedure.

   HINT: 

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

   1. Turn the power switch on (IG) and wait 1.5 seconds or more.
2. Check for DTCs.

   Body Electrical > Pre-Collision 2 > Trouble Codes 

   Result

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

Result: 

A 

END (MILLIMETER WAVE RADAR SENSOR ASSEMBLY WAS DEFECTIVE) 

Result: 

B 

See step  10

1. Replace the driving support ECU assembly.

   HINT: 

   Refer to REMOVAL [11/2015 - 12/2018]

   Result

   Proceed to
   NEXT

Result: 

NEXT 

See step  11

1. Clear the DTCs.

   Body Electrical > Pre-Collision 2 > Clear DTCs 

   Result

   Proceed to
   NEXT

Result: 

NEXT 

See step  12

1. Perform the following procedure.

   HINT: 

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

   1. Turn the power switch on (IG) and wait 1.5 seconds or more.
2. Check for DTCs.

   Body Electrical > Pre-Collision 2 > Trouble Codes 

   Result

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

Result: 

A 

END (DRIVING SUPPORT ECU ASSEMBLY WAS DEFECTIVE) 

Result: 

B 

See step  13

1. Replace the forward recognition camera.

   HINT: 

   Refer to REMOVAL [11/2015 - 07/2020]

2. Perform Forward Recognition Camera Learning.

   HINT: 

   Refer to ADJUSTMENT (SEQUENTIAL RECOGNITION) [11/2015 - 07/2020]

   Result

   Proceed to
   NEXT

Result: 

NEXT 

See step  14

1. Clear the DTCs.

   Body Electrical > Pre-Collision 2 > Clear DTCs 

   Result

   Proceed to
   NEXT

Result: 

NEXT 

See step  15

1. Perform the following procedure.

   HINT: 

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

   1. Turn the power switch on (IG) and wait 1.5 seconds or more.
2. Check for DTCs.

   Body Electrical > Pre-Collision 2 > Trouble Codes 

   Result

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

Result: 

A 

END (FORWARD RECOGNITION CAMERA WAS DEFECTIVE) 

Result: 

B 

See step  16

1. Replace the skid control ECU (brake booster with master cylinder assembly).

   HINT: 

   Refer to REMOVAL [11/2015 - 12/2018]

   Result

   Proceed to
   NEXT

Result: 

NEXT 

END (SKID CONTROL ECU WAS DEFECTIVE)