CAN COMMUNICATION SYSTEM(w/o Central Gateway ECU) HOW TO PROCEED WITH TROUBLESHOOTING

DTC Code	DTC Name
	HOW TO PROCEED WITH TROUBLESHOOTING

CAUTION / NOTICE / HINT

IMPORTANT POINTS CONCERNING TROUBLESHOOTING
Note
- Because the order of diagnosis is important to allow correct diagnosis, make sure to begin troubleshooting using How to Proceed with Troubleshooting when CAN communication system related DTCs are output. If the CAN communication system is malfunctioning.
- If the CAN communication system is malfunctioning, check the contact pressure of the terminals in connectors, as insufficient terminal contact pressure may be the cause.
  
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- Refer to Diagnosis System for the DTCs for the CAN communication system.
- Refer to troubleshooting of each system if DTCs regarding the CAN communication system are not output.
- Before measuring the resistance of the CAN bus, turn the ignition switch off and leave the vehicle for 1 minute or more without operating the key, switches or opening or closing the doors. After that, disconnect the cable from the negative (-) battery terminal and leave the vehicle for 1 minute or more before measuring the resistance.
- After turning the ignition switch off, waiting time may be required before disconnecting the cable from the negative (-) battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) battery terminal notices before proceeding with work.
  
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1. CAN communication DTCs are output for CAN main bus and CAN branch malfunctions as well as for internal malfunctions or power source malfunctions of ECUs or sensors for systems using CAN communication. Therefore, when DTCs for internal malfunctions or power source malfunctions of corresponding systems are output at the same time as CAN communication DTCs, troubleshoot according to the internal malfunction and power source malfunction DTCs.
2. The DLC3 CAN branch wire and V1 bus main bus circuits can be checked for malfunctions by inspecting at the DLC3 terminals using an electrical GTS.
  Note
  - When inspecting at the DLC3, do not connect the GTS directly to the terminals. Instead, connect using service wires.
  - Inspections for an open in an ECU or sensor branch, or inspections for buses other than the V1 bus cannot be performed from the DLC3.
3. An open in a branch for ECUs or sensors that are connected to the CAN main bus can be checked by performing a CAN bus check using the GTS. (This inspection is possible when the DLC3 branch and V1 bus CAN main wire are normal.)
4. If the V1 bus had a communication error, the probable ECU or sensor for which communication stopped can be determined using the combination of communication DTCs (DTCs that start with U) that are output.
5. When an open circuit is detected, before disconnecting related connectors for inspection, push in on the connector body to check that the connector is not loose or disconnected.
6. When a connector is disconnected, check that the terminals and connector body are not cracked, deformed or corroded.

PROCEDURE

VEHICLE BROUGHT TO WORKSHOP

Tech Tips

If the ignition switch can be turned to ON when the vehicle is brought in for repair, check for DTCs and check the illumination condition of the indicators in the combination meter assembly and the basic operation of the vehicle (such as steering operation) promptly.
Do not turn the ignition switch off until the inspection of the vehicle is finished, as some fail-safe functions are canceled when the ignition switch is turned off.
If the ignition switch cannot be turned to ON when the vehicle is brought in, measure the voltage of the battery. If the voltage is below 11 V, recharge or replace the battery before performing troubleshooting.

Result

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CUSTOMER PROBLEM ANALYSIS

Tech Tips

When troubleshooting, confirm that the problem symptoms have been accurately identified. Preconceptions should be discarded in order to make an accurate judgment. To clearly understand what the problem symptoms are, it is extremely important to ask the customer about the problem and the conditions at the time the malfunction occurred.
Ask the customer if the vehicle is/was equipped with additional devices such as a theft deterrent device or monitor. (If equipped, explain the customer that the additional devices will be removed before performing troubleshooting as the malfunction cannot be checked properly.)

It is useful to confirm the symptoms and the conditions in which the vehicle was operating at the time when a malfunction occurred. This helps to narrow down the malfunctioning part.

Tech Tips

What was affected (system, part or meter warning indicators)
What happened (details of the malfunction)
When (occurrence date and time, frequency and if it recurs or not)
Under what kind of situation did the problem occur (driving and operating condition at the occurrence and weather)
Road type or condition (city, suburb, paved road, unpaved road, highway, etc.)
Return conditions (what made the vehicle return to normal. Example: ignition switch was turned off)

Points to be confirmed
Symptom	Air conditioning - Whether the air conditioning system operated - Whether the blower fan operated - The air conditioning functions cannot be operated at all Electric power steering - Normal - A little heavier than usual - There was no assist Drive monitor display - Whether the update of multi-information display items stopped - Whether the numeric part of the drivable distance was displayed - Not displayed at all Eco navigation (eco drive) display - Whether the average fuel consumption graph is updated every minute - Whether the updated section average fuel consumption graph is displayed - Whether the distance-to-empty is displayed on the section average fuel consumption graph display - Not displayed at all Interior lights - Whether the interior light illumination changes when the door is opened or closed - Whether the interior lights turned off when the ignition switch is turned ON - Not illuminated at all Wireless door lock function and entry function - Whether the lock/unlock function operated - Whether the entry warning function operated - Whether the illumination was turned on when the key was brought into a smart detection area 4WD/AWD operation - Normal - Slip detected when starting off Memory call - Normal - Memory write error - Memory read error - Whether the auto return or auto away control is performed Operation of other systems of concern
Meter warning lights	Illumination of warning lights and the order in which they illuminated - Master - Check engine (MIL) - Brake - ABS - Slip - EPS - SRS - Others Meter display - Speedometer - Tachometer - Engine coolant temperature gauge Content displayed on the multi-information display - Whether the odometer to TRIP meter has stopped - Whether the value of the average fuel economy is displayed on the multi-information display - Whether a warning message is displayed on the multi-information display

Result

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CHECK GTS OPERATION

Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.

Check that the GTS and ECUs can communicate with the ignition switch ON.

Tech Tips

If communication is impossible, the GTS screen will indicate an error.
If communication between the GTS and ECUs is impossible, either the GTS or vehicle has a malfunction.
When communication between the GTS and the vehicle is impossible, but communication is possible when the GTS is connected to another vehicle, the vehicle has the malfunction. Inspect the CANH and CANL branch lines of the DLC3 and the ECU power source circuits (in this case perform steps 7 to 9 first). In addition, check that the BAT terminal of the DLC3 receives battery voltage (11 V or more).
If communication between the GTS and ECUs is still impossible even when the GTS is connected to another vehicle, the GTS has a malfunction. Perform the self tests described in the GTS operator's manual. (The GTS may be malfunctioning or its battery may be discharged.)

Result

Result	Proceed to
OK (Communication between the GTS and the vehicle is possible.)	A
OK (Communication between the GTS and the vehicle is impossible but communication is possible when connected to another vehicle.)	B
NG (Communication is not possible between the GTS and the vehicle, nor between the GTS and another vehicle.)	C

GO TO STEP 8 Click here

Refer to GTS operator's manual

CHECK DTC

Using the GTS, perform Health Check to read current and history DTCs and record them.
Note
- CAN communication DTCs are output when there is an open or short in any of the communication lines. Any problems with the power source of a corresponding ECU or sensor, or problems in the ECU or sensor itself also cause these DTCs to be output.
- If a CAN communication line connector is disconnected with the ignition switch ON, the ECUs of the corresponding system and related systems store a DTC.
Tech Tips
- If an open in a CAN main bus line, a short between the CAN bus lines (CANH and CANL) or a +B or ground short in a CAN bus occurs, DTCs of almost all ECUs and sensors on the CAN bus may be output (or a message indicating a communication error may be displayed on the GTS screen). In this case, check the resistance of the CAN bus (steps 7 to 9) first.
- If an open occurs in just one of the lines of a CAN branch, DTCs which are not related to malfunctioning parts may be output (DTCs may be displayed randomly), or a message indicating a communication error may be displayed on the GTS.

Read the freeze frame data using the GTS and record it.

Result

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PERFORM COMMUNICATION MALFUNCTION CHECK (CONNECTION STATUS CHECK USING GTS)

Select "Communication Malfunction Check" from the screen on the GTS.

Record all the DTCs stored for ECUs and sensors.

Result

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PERFORM CAN BUS CHECK (CONNECTION STATUS CHECK USING GTS)

Based on the vehicle equipment and specifications, confirm the systems that use CAN communication.

Click here
Select "CAN Bus Check" from the screen on the GTS.

Observe the screen for approximately 2 minutes to check the ECUs and sensors displayed on the screen.

Result

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CHECK FOR DLC3 CAN BRANCH WIRE AND V1 BUS MAIN WIRE (CANH - CANL)

Note

Before measuring the resistance of the CAN bus, turn the ignition switch off and leave the vehicle for 1 minute or more without operating the key, switches or opening or closing the doors. After that, disconnect the cable from the negative (-) battery terminal and leave the vehicle for 1 minute or more before measuring the resistance.

Tech Tips

Operating the ignition switch, any other switches or a door triggers related ECU and sensor communication on the CAN. This communication will cause the resistance value to change.

Disconnect the cable from the negative (-) battery terminal before measuring the resistances of the CAN main wire and the CAN branch wire.

*a	Front view of DLC3

Measure the resistance according to the value(s) in the table below.

Standard Resistance

Tester Connection	Condition	Specified Condition	Proceed to
G48-6 (CANH) - G48-14 (CANL)	Cable disconnected from negative (-) battery terminal	OK (54 to 69 Ω)	A
G48-6 (CANH) - G48-14 (CANL)	Cable disconnected from negative (-) battery terminal	NG (Higher than 70 Ω)	B
G48-6 (CANH) - G48-14 (CANL)	Cable disconnected from negative (-) battery terminal	NG (Below 53 Ω)	C

GO TO "Open in CAN Main Wire" Click here

GO TO "Short in CAN Bus Lines" Click here

CHECK FOR SHORT TO +B IN CAN V1 BUS (CANH, CANL - BAT)

*a	Front view of DLC3

Measure the resistance according to the value(s) in the table below.

Standard Resistance

Tester Connection	Condition	Specified Condition
G48-6 (CANH) - G48-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher
G48-14 (CANL) - G48-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher

Result

Proceed to
OK
NG

GO TO "Short to B+ in CAN Bus Line" Click here

CHECK FOR SHORT TO GND IN CAN V1 BUS (CANH, CANL - CG)

*a	Front view of DLC3

Measure the resistance according to the value(s) in the table below.

Standard Resistance

Tester Connection	Condition	Specified Condition
G48-6 (CANH) - G48-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher
G48-14 (CANL) - G48-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher

Result

Proceed to
OK
NG

GO TO "Short to GND in CAN Bus Line" Click here

CHECK RESULT OF CAN BUS CHECK (CONNECTION STATUS CHECK USING GTS)

Inspect or repair the probable malfunctioning part based on the check result of step 6 (the step in which CAN bus check was performed).

Result of CAN Bus Check (Connection Status Check Using GTS)

Result	Proceed to
All ECUs and sensors connected to CAN communication are displayed (CAN bus circuit currently normal)	A
An ECU (sensor) that is supposed to be connected to the CAN communication system (V1 bus) is not detected and does not appear on the screen (the CAN branch wire of the ECU (sensor) has an open circuit or there is a loss of communication)	B
ECUs (sensors) that are supposed to be connected to the CAN communication system do not appear on the screen and other ECUs (sensors) appear and reappear on the screen during confirmation (one of the CAN branch wire of the ECU [sensor] has an open circuit)	C

Note

Non-installed ECUs or sensors will not be displayed. Do not mistake them for being in communication stop mode.
It may be possible to select buses that do not have ECUs or sensors from the bus selection pull-down menu on the GTS. This is not a malfunction.

Tech Tips

Regarding CAN Bus Check, refer to How to Interpret CAN Bus Check Screen.

Click here
If the detection status of ECUs changes during the inspection, one of the CAN branch wires of a connected ECU or sensor may be open. (Signals from the ECU or sensor that has an open in one of its CAN branch wires create electrical noise, affecting response to the GTS and whether or not the ECUs and sensors are displayed.)

GO TO "PROBLEM SYMPTOMS TABLE" Click here

GO TO "Open in One Side of CAN Branch Line" Click here

CHECK RESULT OF CHECK COMMUNICATION MALFUNCTION CHECK (SELECT THE MALFUNCTIONING BUS)

Inspect or repair the probable malfunctioning part based on the check result of step 5 (the step in which checking for communication malfunction DTCs was performed).

Tech Tips

When checking for communication DTCs, refer to How to Interpret Communication DTCs (DTCs that start with U).

Click here
If communication DTCs are stored, and all ECUs and sensors connected to the CAN communication system are displayed on the Communication Bus Check (CAN bus check) screen of the GTS, a past malfunction that is currently not occurring is suspected.
Malfunctions in a CAN branch wire of the V1 bus are detected by the corresponding ECUs (sensors). Therefore, determine the location of the malfunction using the combination of output DTCs.

Result

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DTC COMBINATION TABLE

Confirm the problem according to the combination of output DTCs regarding the CAN communication system.

Click here

Tech Tips

CAN communication system history DTCs may indicate the problem if CAN communication system DTCs are output and all ECUs and sensors connected to the CAN communication system are displayed on the CAN Bus Check screen of the GTS.

Result

Result	Proceed to
Combination of DTCs is not in DTC Combination Table	A
Combination of DTCs is in DTC Combination Table	B

GO TO COMMUNICATION STOP MODE TABLE Click here

IDENTIFICATION OF PROBLEM (PAST MALFUNCTION IN MAIN BUS OF V1 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
Clear the DTCs using the GTS.
Perform a malfunction simulation test on all harnesses and connectors related to the V1 bus CAN main wire.

Based on the results of the check, inspect the parts that output DTCs to determine the malfunctioning part.

Tech Tips

If DTCs are output, do not turn the ignition switch off.

Result

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REPAIR AND REPLACE

Result

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CONFIRMATION TEST

Result

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END