PRE-COLLISION SYSTEM, Diagnostic DTC:U023A

DTC Code	DTC Name
U023A	Lost Communication with Front Camera Module

DESCRIPTION

The pre-collision city sensor is connected to the skid control ECU (brake actuator assembly) via CAN communication. If communication with the skid control ECU (brake actuator assembly) stops, the pre-collision city sensor stores DTC U023A.


DTC Code	DTC Detection Condition	Trouble Area
U023A	Both of the following conditions are met: All of the following conditions are met: 3 seconds have elapsed since the ignition switch was turned ON. The battery voltage is 10 V or more for 3 seconds or more. Both of the following conditions are met for 1 second or more: The pre-collision city sensor can receive data from the skid control ECU (brake actuator assembly). The skid control ECU (brake actuator assembly) receives a communication error signal from the pre-collision city sensor.	CAN communication system Pre-collision city sensor Skid control ECU (Brake actuator assembly)

CAUTION / NOTICE / HINT

Note:

When replacing the pre-collision city sensor, replace it with a new one and be sure to initialize the settings. If a pre-collision city sensor which was installed to another vehicle is used, the information stored in the pre-collision city sensor will not match the information from the vehicle and, as a result, a DTC may be stored.
If the pre-collision city sensor has been replaced, or the windshield glass has been replaced or removed/installed, be sure to perform Pre-collision City Sensor Learning (Click here).

PROCEDURE

CHECK FOR DTCs (PRE-CRASH SAFETY SYSTEM)

Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Enter the following menus: Chassis / PCS/LDA/RSA/LVN / Trouble Codes.
Clear the DTCs (Click here).
Make sure that the DTC detection conditions are met.

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

Check for DTCs (Click here).

Table 1. Result
Result	Proceed to
Only DTC U023A is output	A
DTC U023A and other DTCs are output	B

GO TO DIAGNOSTIC TROUBLE CODE CHART

(Click here Click here)

CHECK FOR DTCs (VEHICLE STABILITY CONTROL SYSTEM)

Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Enter the following menus: Chassis / ABS/VSC/TRC / Trouble Codes.
Clear the DTCs (Click here).
Make sure that the DTC detection conditions are met.

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

Check for DTCs (Click here).

Tip:

If the pre-collision system outputs U023A, DTCs from the VSC system may also be output. Therefore, first check the VSC system.

Table 2. Result
Result	Proceed to
Vehicle stability control system DTCs are not output	A
Vehicle stability control system DTCs are output	B

GO TO VEHICLE STABILITY CONTROL SYSTEM

(Click here)

TEST MODE INSPECTION (VEHICLE STABILITY CONTROL SYSTEM)
Tip:
- Signals related to the VSC system can be inspected by entering test mode.
- The VSC system does not operate in test mode, regardless of whether the sensor check is normal or abnormal.
- If a malfunction occurs in a sensor, the ABS warning light and slip indicator light illuminate and ABS does not operate.
- When entering test mode, the skid control ECU in the brake actuator assembly communicates with the pre-collision city sensor and determines whether the vehicle is equipped with the pre-collision system. Therefore, after entering test mode, it is necessary to maintain the test mode condition for 5 seconds.
1. Entering test mode
  1. Turn the ignition switch OFF.
  2. Make sure the shift lever is in P.
  3. Connect the GTS to the DLC3.
  4. Turn the ignition switch to ON.
  5. Turn the GTS on.
  6. Enter the following menus: Chassis / ABS/VSC/TRC / Utility / Signal Check.
  7. Put the steering wheel in the neutral position.
  8. Start the engine.
    
    Tip:
    After entering test mode, maintain the test mode condition for 5 seconds. If test mode is ended before 5 seconds elapse, U023A may be output. If U023A is output after test mode ends, enter test mode again, wait 5 seconds, and then check for DTCs again.
2. Check test mode display
  1. When entering test mode, check that the ABS warning light and slip indicator light enter the test mode pattern (blinking 0.25 seconds on and 0.25 seconds off).
    
    Tip:
    If a part or wiring is defective when entering test mode, the ABS warning light and slip indicator light remain on or off.
3. Ending test mode
  1. Turn the ignition switch OFF.
  2. Remove the GTS.

CHECK FOR DTCs (PRE-CRASH SAFETY SYSTEM)

Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Enter the following menus: Chassis / PCS/LDA/RSA/LVN / Trouble Codes.
Clear the DTCs (Click here).
Make sure that the DTC detection conditions are met.

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

Check for DTCs (Click here).

Table 3. Result
Result	Proceed to
DTC U023A is not output	A
DTC U023A is output	B

END

REPLACE PRE-COLLISION CITY SENSOR
1. Replace the pre-collision city sensor (Click here Click here).
2. Adjust the pre-collision city sensor (Click here).

CHECK FOR DTCs (PRE-CRASH SAFETY SYSTEM)

Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Enter the following menus: Chassis / PCS/LDA/RSA/LVN / Trouble Codes.
Clear the DTCs (Click here).
Make sure that the DTC detection conditions are met.

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

Check for DTCs (Click here).

Table 4. Result
Result	Proceed to
DTC U023A is not output	A
DTC U023A is output	B

END (PRE-COLLISION CITY SENSOR WAS DEFECTIVE)

REPLACE SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY)
1. Replace the skid control ECU (brake actuator assembly) (Click here).
END (SKID CONTROL ECU [BRAKE ACTUATOR ASSEMBLY] WAS DEFECTIVE)