How To Proceed With Troubleshooting

HINT:

• CAN communication DTCs are output when there is an open or short in any of the communication wires. Any problems with the power source of a corresponding ECU or sensor, or problems in the ECU or the sensor itself also cause these DTCs to be output.
• If a CAN communication wire connector is disconnected with the engine switch on (IG), the ECUs of the corresponding system and related systems record a DTC.

1. Check if the vehicle is equipped with any of the following: Navigation system, intuitive parking assist system, seat position memory system, AFS (Adaptive front-lighting system), pre-collision system, and dynamic radar cruise control system (See DIAGNOSIS SYSTEM  ).

1. Using the intelligent tester, display the "BUS CHECK" screen (See DIAGNOSIS SYSTEM  ).
2. Observe the screen for approximately 1 minute to check the ECUs and sensors displayed on the screen.

   Result 

   RESULT REFERENCE
   
   

   Symptom	Proceed to
   All ECUs and sensors connected to the CAN communication system are not displayed on the screen. (Open in CAN No. 1 main bus wire or short in CAN No. 1 bus wire)	A
   One of the ECUs and sensors connected to the CAN communication system is not displayed on the screen. (Open in ECU or sensor branch wires, or communication interrupted)	B(*1) (See DIAGNOSIS SYSTEM  )
   Some of the ECUs and sensors connected to the CAN communication system are not displayed on the screen. During this check, some ECUs and sensors repeatedly appear and disappear from the screen. (Open in one side of ECU or sensor branch wires)	C (See OPEN IN ONE SIDE OF CAN BRANCH LINE  )
   All ECUs and sensors except the main body ECU connected to the MS CAN bus wire are not displayed on the screen. The main body ECU outputs DTC B2326. (Open in CAN MS main bus wire or short in CAN MS bus wire)	D (See DTC B2326 CAN MS Bus Line Communication Malfunction  )
   All ECUs and sensors connected to the MS CAN bus wire are not displayed on the screen. (Open in main body ECU branch wire or main body ECU malfunction)	E (See MAIN BODY ECU COMMUNICATION STOP MODE  )
   All ECUs and sensors except the gateway ECU connected to the CAN No. 2 bus wire are not displayed on the screen. The gateway ECU outputs DTC U1002. (Open in CAN No. 2 main bus wire or short in CAN No. 2 bus wire)	F (See DTC U1002 Lost Communication with Gateway Module  )
   All ECUs and sensors connected to the CAN No. 2 bus wire are not displayed on the screen. (Open in gateway ECU branch wire or gateway ECU malfunction)	G (See GATEWAY ECU COMMUNICATION STOP MODE  )
   All ECUs and sensors connected to the CAN communication system are displayed on the screen. (CAN bus circuit is currently normal)	H

   NOTE:

   • The systems (ECUs, sensors) that adopt CAN communication vary depending on the vehicle and optional equipment. Check which systems (ECUs, sensors) are installed on the vehicle (See DIAGNOSIS SYSTEM  ).
   • Non-installed ECUs or sensors will not be displayed. Do not mistake them for being in the communication stop mode.
   • If only ECT is not displayed, check DTC U0101 of the SFI system (See DTC U0101 LOST COMMUNICATION WITH TCM ).
   • The ECUs and sensors that repeatedly appear and disappear from the screen during this check are considered normal. (The response to the intelligent tester and the tester display are affected by signals output from other ECUs which have an open circuit in either of their CAN branch wires.)

   HINT:

   • (*1): See the "DTC CHART " instead of the "COMMUNICATION STOP MODE TABLE", when some of the ECUs connected to the CAN MS bus or the CAN No. 2 bus are not displayed on the screen (See DIAGNOSTIC TROUBLE CODE CHART  ).
   • The ECUs connected to the CAN MS bus are displayed on the screen by the main body ECU.
   • The ECUs connected to the CAN No. 2 bus are displayed on the screen by the gateway ECU.
   • If communication stops between an ECU and the CAN No. 2 bus, the ECU will not be displayed on the intelligent tester screen.

B: COMMUNICATION STOP MODE TABLE (*1) 

C: GO TO "OPEN IN ONE SIDE OF CAN BRANCH WIRE" 

D: GO TO " B2326  " 

E: GO TO " MAIN BODY ECU COMMUNICATION STOP MODE  " 

F: GO TO " U1002  " 

G: GO TO " GATEWAY ECU COMMUNICATION STOP MODE  " 

H: GO TO STEP  5

A: Go to Next Step 

1. Check the CAN No. 1 bus wire (See CAN BUS LINE  ).

   HINT:

   If the area where an open or short is occurring in a CAN No. 1 bus wire can be determined, refer to the "PROBLEM SYMPTOMS TABLE ."

NEXT: GO TO STEP  6

HINT;

• Sometimes CAN communication system DTCs are output, but all the ECUs and sensors connected to the CAN communication system are displayed on the intelligent tester. In this case, previous or history DTCs may indicate the cause of the problem.
• ECUs related to a problem in the CAN No. 1 bus will store DTCs to indicate communication malfunctions. The communication stop mode in the CAN No. 1 bus can be determined by comparing the combination of DTCs that have been set. Refer to the DTC combination table for the CAN No. 1 bus.
• The main body ECU will store communication error DTCs when the ECUs connected to the CAN MS bus cannot communicate, or if a network malfunction occurs.
• The gateway ECU will store communication error DTCs when the ECUs connected to the CAN No. 2 bus cannot communicate, or if a network malfunction of the CAN No. 2 bus occurs.

  Result 

  RESULT REFERENCE
  
  

  Result	Proceed to
  Communication error DTCs other than the codes output from the main body ECU and the gateway ECU are output.	A
  The main body ECU outputs CAN MS DTC B2326. (A malfunction occurred in the CAN MS bus)	B (See DTC B2326 CAN MS Bus Line Communication Malfunction  )
  The main body ECU outputs DTCs other than CAN MS bus DTC B2326. (A malfunction occurred in an ECU branch wire connected to the CAN MS bus)	C (See DIAGNOSTIC TROUBLE CODE CHART  )
  The gateway ECU outputs network trouble code U1002. (A malfunction occurred in the CAN No. 2 bus)	D (See DTC U1002 Lost Communication with Gateway Module  )
  The gateway ECU outputs DTCs other than network trouble code U1002. (A malfunction occurred in an ECU branch wire connected to the CAN No. 2 bus)	E (See DIAGNOSTIC TROUBLE CODE CHART  )

B: GO TO " B2326  " 

C: GO TO " DTC CHART  " 

D: GO TO " U1002  " 

E: GO TO " DTC CHART  " 

A: Go to Next Step 

1. Confirm trouble according to the combination of output DTCs regarding the CAN communication system (See DIAGNOSIS SYSTEM  ).

   HINT:

   Previous CAN communication system DTCs may be the cause if CAN communication system DTCs are output and all ECUs and sensors connected to the CAN communication system are displayed on the intelligent tester's "BUS CHECK" screen via the CAN VIM.

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