IMPORTANT POINTS CONCERNING TROUBLESHOOTING
CAUTION:
Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.
Note
Refer to the troubleshooting procedures of each system if DTCs regarding the CAN communication system are not output.
Before measuring the resistance, leave the vehicle for at least 1 minute and do not operate the engine switch, any switches or any doors. If doors need to be opened in order to check connectors, open the doors and leave them open.
After turning the engine switch off, waiting time may be required before disconnecting the cable from the battery terminal. Therefore, make sure to read the disconnecting the cable from the battery terminal notice before proceeding with work Click here.
When disconnecting the cable, some systems need to be initialized after the cable is reconnected Click here.
Tech Tips
Operating the engine switch, any switches or any doors triggers related ECU and sensor communication with the CAN, which causes resistance variation.
*: Use the intelligent tester.
DTCs indicating a CAN communication malfunction are also stored due to internal or power source-related problems in ECUs or sensors of systems using CAN communication. Therefore, check whether codes indicating internal or power source-related problems in those systems are output together with the CAN communication DTCs.
It is possible to inspect the circuit of the DLC3 branch line or V bus main line for malfunctions by inspecting the terminals of the DLC3 using SST.
Note
It is only possible to inspect branch lines to ECUs (sensors) or the V bus from the DLC3.
It is possible to check which ECUs (sensors) are not able to communicate via CAN communication by checking the "Bus Check" function of the intelligent tester (when the DLC3 CAN branch wire and V bus CAN main wire are normal).
Tech Tips
When checking "Bus Check", ECUs (sensors) whose branch line is open or that cannot communicate via CAN communication do not respond to the intelligent tester (they are not displayed on the screen).
When checking "Bus Check", if a DTC indicating a CAN communication malfunction is output even though all ECUs (sensors) respond (they are displayed on the screen), use the DTC combination table to determine the suspected trouble area and perform symptom simulation.
For past malfunctions of the V bus, the ECUs (sensors) which cannot communicate via CAN communication can be determined from the combination of CAN communication DTCs that are output.
The skid control ECU assembly detects malfunctions in the steering bus circuit and stores DTCs depending on the malfunctioning areas. The ECUs (sensors) which cannot communicate via CAN communication can be determined from the combination of CAN communication DTCs that are output.
The ECM detects malfunctions in the braking and driving bus circuit and stores DTCs depending on the malfunctioning areas. The ECUs (sensors) which cannot communicate via CAN communication can be determined from the combination of CAN communication DTCs that are output.
The main body ECU detects malfunctions in the MS bus circuit and stores DTCs depending on the malfunctioning areas. The ECUs (sensors) which cannot communicate via CAN communication can be determined from the combination of CAN communication DTCs that are output.
The driving support ECU assembly detects malfunctions in the parking assist bus circuit and outputs DTCs depending on the malfunctioning areas. The ECUs (sensors) which cannot communicate via CAN communication can be determined from the combination of CAN communication DTCs that are output.
The network gateway ECU detects malfunctions in the WIL bus circuit and outputs DTCs depending on the malfunctioning areas. The ECUs (sensors) which cannot communicate via CAN communication can be determined from the combination of CAN communication DTCs that are output.
When an open circuit malfunction is confirmed, before disconnecting the connectors for inspection, check whether the connectors are loose by pushing in the connector case.
When a connector is disconnected, check if the connector terminals or case is damaged, deformed, deteriorated, etc.
VEHICLE BROUGHT TO WORKSHOP
NEXT |
INSPECT BATTERY VOLTAGE
Standard voltage |
---|
11 to 14 V |
If the voltage is below 11 V, recharge or replace the battery before proceeding.
NEXT |
CHECK FOR DTC*
Using the intelligent tester, check for all DTCs.
Note
If codes indicating internal or power source-related malfunctions of ECUs or sensors are output together with codes indicating that those ECUs or sensors cannot communicate via CAN communication, it is likely that the problem is not in the CAN communication line. Therefore, perform troubleshooting for the DTCs related to the malfunctioning parts first.
If a connector of a system which includes a CAN communication line is disconnected when the engine switch is on (IG) or on (ACC), CAN communication DTCs will be stored by that system and any related systems.
NEXT |
CHECK INSTALLED SYSTEMS (ECU AND SENSOR) THAT USE CAN COMMUNICATION
Based on the vehicle equipment and specifications, confirm the systems that use CAN communication Click here.
NEXT |
CHECK FOR OPEN CIRCUIT IN DLC3 BRANCH WIRE AND V BUS CIRCUIT CAN MAIN WIRE AND SHORT CIRCUIT (CANH - CANL)
Disconnect the cable from the negative (-) battery terminal before measuring the resistances of the CAN main wire and CAN branch wire.
*a | Front view of DLC3 |
Measure the resistance according to the value(s) in the table below.
Standard Resistance | ||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
B |
Go to "Open in CAN Main Wire" Click here |
C |
Go to "Short in CAN Bus Lines" Click here |
A |
CHECK FOR SHORT TO +B IN CAN V BUS (CANH, CANL - BAT)
*a | Front view of DLC3 |
Measure the resistance according to the value(s) in the table below.
Standard Resistance | |||||||||
---|---|---|---|---|---|---|---|---|---|
|
NG |
Go to "Short to B+ in CAN Bus Lines" Click here |
OK |
CHECK FOR SHORT TO GND IN CAN V BUS (CANH, CANL - CG)
*a | Front view of DLC3 |
Measure the resistance according to the value(s) in the table below.
Standard Resistance | |||||||||
---|---|---|---|---|---|---|---|---|---|
|
NG |
Go to "Short to GND in CAN Bus Lines" Click here |
OK |
CHECK ECUS CONNECTED TO CAN BUS*
Connect the cable to the negative (-) battery terminal.
Note
When disconnecting the cable, some systems need to be initialized after the cable is reconnected Click here.
Select "Bus Check" from "System Select" Click here.
Check the display of the connected ECUs and sensors for a minute.
Result | Proceed to |
---|---|
All ECUs and sensors connected to CAN communication system are displayed on screen (CAN bus circuit currently normal) | A |
Except for skid control ECU assembly, no ECUs connected to steering bus are displayed (steering bus CAN main wire open or short malfunction) | B |
No ECUs connected to steering bus are displayed (CAN branch wire between skid control ECU assembly and V bus circuit is open) | C |
Except for ECM, no ECUs connected to braking and driving bus are displayed (braking and driving bus CAN main wire open or short malfunction) | D |
No ECUs connected to braking and driving bus are displayed (CAN branch wire between ECM and V bus circuit is open) | E |
Except for main body ECU, no ECUs connected to MS bus are displayed (MS bus CAN main wire open or short malfunction) | F |
No ECUs connected to MS bus are displayed (CAN branch wire between main body ECU and V bus circuit is open) | G |
Except for driving support ECU assembly, no ECUs connected to parking assist bus are displayed (parking assist bus CAN main wire open or short malfunction) | H |
No ECUs connected to parking assist bus are displayed (CAN branch wire between driving support ECU assembly and MS bus, braking and driving bus and steering bus circuit is open) | I |
Except for network gateway ECU, no ECUs connected to WIL bus are displayed (WIL bus CAN main wire open or short malfunction) | J |
No ECUs connected to WIL bus are displayed (CAN branch wire between steering bus circuit is open) | K |
Single ECU or sensor that should be connected to CAN communication is not displayed (ECU or sensor CAN branch wire open or communication stop) | L |
ECU or sensor that should be connected to CAN communication is not displayed or display is intermittent during check (ECU or sensor CAN branch wire open on one side) | M |
Note
ECUs and sensors that are not present will not be displayed. Be careful not to mistake them for communication stop malfunctions.
Tech Tips
If the display of an ECU is intermittent during the check, one side of an ECU or sensor CAN branch wire is open (the signal of the ECU is treated as noise, which affects the response and display of the intelligent tester).
The skid control ECU assembly checks for proper ECU communication for ECUs that are connected to the steering bus and the results are displayed on the intelligent tester. ECUs that stop communicating with the skid control ECU assembly for 3 seconds or more will stop being displayed on the intelligent tester.
The skid control ECU assembly may be malfunctioning if both of the following occur: 1) all ECUs connected to the steering bus are not displayed on the intelligent tester; and 2) DTC U1005 Lost Communication with Gateway Module is not output.
The ECM checks for proper ECU communication for ECUs that are connected to the braking and driving bus and the results are displayed on the intelligent tester. ECUs that stop communicating with the ECM for 3 seconds or more will stop being displayed on the intelligent tester.
The ECM may be malfunctioning if both of the following occur: 1) all ECUs connected to the braking and driving bus are not displayed on the intelligent tester; and 2) DTC U1004 Lost Communication with Gateway Module is not output.
The main body ECU checks for proper ECU communication for ECUs that are connected to the MS bus and the results are displayed on the intelligent tester. ECUs that stop communicating with the main body ECU for 10 seconds or more will stop being displayed on the intelligent tester.
The main body ECU may be malfunctioning if both of the following occur: 1) all ECUs connected to the MS bus are not displayed on the intelligent tester; and 2) DTC U1002 Lost Communication with Gateway Module (MS Bus) is not output.
The driving support ECU assembly checks for proper ECU communication for ECUs that are connected to the parking assist bus and the results are displayed on the intelligent tester. ECUs that stop communicating with the driving support ECU assembly for 10 seconds or more will stop being displayed on the intelligent tester.
The driving support ECU assembly may be malfunctioning if both of the following occur: 1) all ECUs connected to the parking assist bus are not displayed on the intelligent tester; and 2) DTC U1002 Lost Communication with Gateway Module (Parking Assist Bus) is not output.
The network gateway ECU checks for proper ECU communication for ECUs that are connected to the WIL bus and the results are displayed on the intelligent tester. ECUs that stop communicating with the driving support ECU assembly for 10 seconds or more will stop being displayed on the intelligent tester.
The network gateway ECU may be malfunctioning if both of the following occur: 1) all ECUs connected to the WIL bus are not displayed on the intelligent tester; and 2) DTC U1002 Lost Communication with Gateway Module is not output.
B |
Go to "DTC U1005" Click here |
C |
Go to "Skid Control ECU Communication Stop Mode" Click here |
D |
Go to "DTC U1004" Click here |
E |
Go to "ECM Communication Stop Mode" Click here |
F |
Go to "DTC U1002" Click here |
G |
Go to "Main Body ECU Communication Stop Mode" Click here |
H |
Go to "DTC U1002" Click here |
I |
Go to "DTC U1101" Click here |
J |
Go to "DTC U1002" Click here |
K |
Go to "DTC U0147" Click here |
L |
Go to "Problem Symptoms Table" Click here |
M |
Go to "Open in One Side of CAN Branch Line" Click here |
A |
CHECK COMMUNICATION MALFUNCTION DTC (PAST DTC CHECK)*
Select "Bus Check" from "System Select" Click here.
Write down all of the DTCs output from each ECU.
Tech Tips
If there are communication malfunction DTCs output but the intelligent tester "Bus Check - Communication Bus Check" screen displays all of the ECUs and sensors connected to the CAN communication system, the communication malfunction DTCs may be past malfunctions that are no longer present.
For V bus main wire malfunctions, DTCs for related ECUs are also output. Therefore, determine the malfunctioning area based on all of the DTCs that are output.
For steering bus malfunctions, DTCs are stored based on the detection of communication stop malfunctions and network malfunctions of ECUs that are connected by the skid control ECU assembly.
For braking and driving bus malfunctions, DTCs are stored based on the detection of communication stop malfunctions and network malfunctions of ECUs that are connected by the ECM.
For MS bus malfunctions, DTCs are stored based on the detection of communication stop malfunctions and network malfunctions of ECUs that are connected by the main body ECU.
For parking assist bus malfunctions, DTCs are stored based on the detection of communication stop malfunctions and network malfunctions of ECUs that are connected by the driving support ECU assembly.
For WIL bus malfunctions, DTCs are stored based on the detection of communication stop malfunctions and network malfunctions of ECUs that are connected by the network gateway ECU.
Result | Proceed to |
---|---|
ECU connected to V bus outputs communication trouble code | A |
Skid control ECU assembly outputs network malfunction trouble code (U1005) (steering bus CAN main wire past malfunction) |
B |
ECM outputs network malfunction trouble code (U1004) (braking and driving bus CAN main wire past malfunction) |
C |
Main body ECU outputs network malfunction trouble code (U1002) (MS bus CAN main wire past malfunction) |
D |
Driving support ECU assembly outputs network malfunction trouble code (U1002) (parking assist bus CAN main wire past malfunction) |
E |
Network gateway ECU outputs network malfunction trouble code (U1002) (WIL bus CAN main wire past malfunction) |
F |
Skid control ECU assembly outputs trouble code other than the network malfunction trouble code (U1005) (past malfunction of ECU or CAN branch wire connected to steering bus) |
G |
ECM outputs trouble code other than network malfunction trouble code (U1004) (past malfunction of ECU or CAN branch wire connected to braking and driving bus) |
G |
Main body ECU outputs trouble code other than network malfunction trouble code (U1002) (past malfunction of ECU or CAN branch wire connected to MS bus) |
G |
Driving support ECU assembly outputs trouble code other than network malfunction trouble code (U1002) (past malfunction of ECU or CAN branch wire connected to parking assist bus) |
G |
Network gateway ECU outputs trouble code other than network malfunction trouble code (U1002) (past malfunction of ECU or CAN branch wire connected to WIL bus) |
G |
B |
Go to "DTC U1005" Click here |
C |
Go to "DTC U1004" Click here |
D |
Go to "DTC U1002" Click here |
E |
Go to "DTC U1002" Click here |
F |
Go to "DTC U1002" Click here |
G |
Go to DIAGNOSTIC TROUBLE CODE CHART" Click here |
A |
CHECK DTC COMBINATION TABLE (V BUS BRANCH WIRE OPEN, PAST COMMUNICATION STOP MALFUNCTION)
Based on the combination of output CAN communication system DTCs, determine which ECUs and sensors have a communication stop malfunction Click here.
NEXT |
PERFORM MALFUNCTION SIMULATION TEST (V BUS CIRCUIT MAIN WIRE PAST MALFUNCTION)*
Using the intelligent tester, clear all DTCs.
Perform a malfunction simulation test on all harnesses and connectors related to the V bus CAN main wire.
Check the DTCs that were output as a result of the malfunction simulation test. Then determine the malfunctioning area.
NEXT |
ADJUST, REPAIR AND REPLACE
NEXT |
CLEAR DTC*
Using the intelligent tester, clear all DTCs.
NEXT |
CONFIRMATION TEST
NEXT |
END |