How to Proceed With Troubleshooting
NETWORKING: CAN COMMUNICATION SYSTEM: HOW TO PROCEED WITH TROUBLESHOOTING
1. IMPORTANT POINT CONCERNING TROUBLESHOOTING
CAUTION:
Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.
NOTICE:
* 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 ignition switch, any switches or any doors. If doors need to be opened in order to check connectors, open the doors and leave them open.
* When disconnecting the cable, some systems need to be initialized after the cable is reconnected Repair Instruction - Initialization.
HINT
* Operating the ignition switch, any switches or any doors triggers related ECU and sensor communication with the CAN, which causes resistance variation.
* *: Use the Techstream.
(a) 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.
(b) It is possible to inspect the circuit of the DLC3 branch line or V1 bus main line for malfunctions by inspecting the terminals of the DLC3 using SST.
NOTICE:
It is only possible to inspect branch lines to ECUs (sensors) or the V1 bus from the DLC3.
(c) It is possible to check which ECUs (sensors) are not able to communicate via CAN communication by checking the "Bus Check" function of the Techstream (when the DLC3 CAN branch wire and V1 bus CAN main wire are normal).
HINT
* When checking "Bus Check", ECUs (sensors) whose branch line is open or that cannot communicate via CAN communication do not respond to the Techstream (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.
(d) For past malfunctions of the V1 bus, the ECUs (sensors) which cannot communicate via CAN communication can be determined from the combination of CAN communication DTCs that are output.
(e) The power source control ECU (Power Management2) detects malfunctions in the power management 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.
(f) 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.
(g) When a connector is disconnected, check if the connector terminals or case is damaged, deformed, deteriorated, etc.
1. VEHICLE BROUGHT TO WORKSHOP
NEXT -- Continue to next step.
2. INSPECT BATTERY VOLTAGE
Standard voltage:
11 to 14 V
If the voltage is below 11 V, recharge or replace the battery before proceeding.
NEXT -- Continue to next step.
3. CHECK AND CLEAR DTC*
(a) Using the Techstream, perform the all DTCs check.
NOTICE:
* 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 ignition switch is ON or ACC, CAN communication DTCs will be stored by that system and any related systems.
NEXT -- Continue to next step.
4. CHECK INSTALLED SYSTEMS (ECU AND SENSOR) THAT USE CAN COMMUNICATION
(a) Based on the vehicle equipment and specifications, confirm the systems that use CAN communication Diagnosis System.
NEXT -- Continue to next step.
5. CHECK FOR OPEN CIRCUIT IN DLC3 CAN BRANCH WIRE AND V1 BUS CIRCUIT CAN MAIN WIRE AND CHECK FOR SHORT CIRCUIT (CANH - CANL)
(a) Disconnect the cable from the negative (-) battery terminal before measuring the resistances of the CAN main wire and CAN branch wire.
(b) Measure the resistance of the DLC3.
Standard Resistance:
Text in Illustration
B -- Go to "Open in CAN Main Wire" Open in CAN Main Wire
C -- Go to "Short in CAN Bus Lines" Short in CAN Bus Lines
A -- Continue to next step.
6. CHECK FOR SHORT TO +B IN CAN V1 BUS (CANH, CANL - BAT)
(a) Measure the resistance of the DLC3.
Standard Resistance:
Text in Illustration
NG -- Go to "Short to B+ in CAN Bus Line" Short to B+ in CAN Bus Line
OK -- Continue to next step.
7. CHECK FOR SHORT TO GND IN CAN V1 BUS (CANH, CANL - CG)
(a) Measure the resistance of the DLC3.
Standard Resistance:
Text in Illustration
NG -- Go to "Short to GND in CAN Bus Line" Short to GND in CAN Bus Line
OK -- Continue to next step.
8. CHECK ECUS CONNECTED TO CAN BUS*
(a) Connect the cable to the negative (-) battery terminal.
NOTICE:
When disconnecting the cable, some systems need to be initialized after the cable is reconnected Repair Instruction - Initialization.
(b) Select "Bus Check" from "System Select".
(c) Check the display of the connected ECUs and sensors for a minute.
Result
NOTICE:
ECUs and sensors that are not present will not be displayed. Be careful not to mistake them for communication stop malfunctions.
HINT
* 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 Techstream).
* The power source control ECU checks for proper ECU communication for ECUs that are connected to the power management bus and the results are displayed on the Techstream. ECUs that stop communicating with the power source control ECU for 3 seconds or more will stop being displayed on the Techstream.
B -- Go to "Power Source Control ECU Communication Stop Mode" Power Management Control ECU Communication Stop Mode
C -- Go to "PROBLEM SYMPTOMS TABLE" Problem Symptoms Table
D -- Go to "Open in One Side of CAN Branch Line" Open in One Side of CAN Branch Line
A -- Continue to next step.
9. CHECK COMMUNICATION MALFUNCTION DTC (PAST DTC CHECK)*
(a) Select "Bus Check" from "System Select".
(b) Write down all of the DTCs stored in each ECU.
HINT
* If there are communication malfunction DTCs output but the Techstream "Bus Check - Communication Bus Check" screen displays all of the ECUs and sensors connected to the CAN system, the communication malfunction DTCs may be past malfunctions that are no longer present.
* For V1 bus CAN 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 power management bus malfunctions, DTCs are stored based on the detection of communication stop malfunctions and network malfunctions of ECUs that are connected by the power source control ECU.
Result
B -- Go to "DIAGNOSTIC TROUBLE CODE CHART" CAN Communication System
A -- Continue to next step.
10. CHECK DTC COMBINATION TABLE (V1 BUS CAN BRANCH WIRE OPEN, PAST COMMUNICATION STOP MALFUNCTION)
(a) Based on the combination of output CAN communication system DTCs, determine which ECUs and sensors have a communication stop malfunction Diagnosis System.
NEXT -- Continue to next step.
11. PERFORM MALFUNCTION SIMULATION TEST (V1 BUS CIRCUIT CAN MAIN WIRE PAST MALFUNCTION)*
(a) Using the Techstream, clear all DTCs.
(b) Perform a malfunction simulation test on all harnesses and connectors related to the V1 bus CAN main wire.
(c) Check the DTCs that were output as a result of the malfunction simulation test. Then determine the malfunctioning area.
NEXT -- Continue to next step.
12. ADJUST, REPAIR AND REPLACE
NEXT -- Continue to next step.
13. CLEAR DTC*
(a) Using the Techstream, clear all DTCs.
NEXT -- Continue to next step.
14. CONFIRMATION TEST
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