PRECAUTIONS WHEN 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, check the contact pressure of the terminals in connectors, as insufficient terminal contact pressure may be the cause Click here.
Refer to Diagnosis System for CAN communication system DTCs.
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 Click here.
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.
The DLC3 branch and V bus main bus circuits can be checked for malfunctions by inspecting at the DLC3 terminals using an electrical tester.
Note
When inspecting at the DLC3 connector, do not connect the tester 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 V bus cannot be performed from the DLC3.
An open in a branch for ECUs or sensors that are connected to the CAN main bus can be checked by performing a communication bus check using the intelligent tester. (This inspection is possible when the DLC3 branch and V bus main bus lines are normal.)
If the V 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.
If a sub bus has a communication error, the gateway function equipped ECU (sub bus monitor ECU) detects it and stores DTCs related to the error.
Tech Tips
On the intelligent tester, gateway function equipped ECUs display DTCs for ECUs connected to the sub bus.
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.
When a connector is disconnected, check that the terminals and connector body are not cracked, deformed or corroded.
VEHICLE BROUGHT TO WORKSHOP
Tech Tips
If the ignition switch can be turned to ON (the power source mode can be changed to on (IG)) 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 (the power source mode cannot be changed to on (IG)) 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.
If the ignition switch cannot be turned to ON even though the battery voltage is normal, repair this malfunction before performing troubleshooting Click here.
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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 to 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, for example, the ignition switch was turned off)
Symptom |
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Meter warning lights |
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*1: w/ Multi-information Display
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CHECK INTELLIGENT TESTER OPERATION
Tech Tips
Read the intelligent tester operators manual before use Click here.
Connect the intelligent tester to the DLC3.
Turn the ignition switch to ON.
Turn the intelligent tester on.
Check that the intelligent tester and ECUs can communicate with the ignition switch ON.
Tech Tips
If communication is not possible, the intelligent tester screen will indicate an error.
If communication between the intelligent tester and ECUs is not possible, either the intelligent tester or vehicle has a malfunction.
When communication between the intelligent tester and the vehicle is not possible, but communication is possible when the intelligent tester 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 intelligent tester and ECUs is still not possible even when the intelligent tester is connected to another vehicle, the intelligent tester has the malfunction. Perform the self tests described in the intelligent tester operators manual. (The intelligent tester may be malfunctioning or its battery may be discharged.)
Result | Proceed to |
---|---|
OK (Communication between the intelligent tester and the vehicle is possible.) | A |
OK (Communication between the intelligent tester and the vehicle is not possible but communication is possible when connected to another vehicle.) | B |
NG (Communication is not possible between the intelligent tester and the vehicle, nor between the intelligent tester and another vehicle.) | C |
B |
Go to step 7 |
C |
Refer to intelligent tester operator's manual |
A |
CHECK DTC
Using the intelligent tester, perform All Codes 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 intelligent tester 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 intelligent tester.
Read the freeze frame data using the intelligent tester and record it.
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PERFORM COMMUNICATION MALFUNCTION DTCs (CONNECTION STATUS CHECK USING INTELLIGENT TESTER)
Select "Communication Malfunction DTC" from the screen on the intelligent tester.
Record all the DTCs stored for ECUs and sensors.
NEXT |
PERFORM COMMUNICATION BUS CHECK (CONNECTION STATUS CHECK USING INTELLIGENT TESTER)
Based on the vehicle equipment and specifications, confirm the systems that use CAN communication Click here.
Select "Communication Bus Check" from the screen on the intelligent tester.
Observe the screen for approximately 2 minutes to check the ECUs and sensors displayed on the screen.
NEXT |
CHECK DLC3 BRANCH LINE AND V BUS MAIN LINE (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.
*1 | DLC3 |
Disconnect the cable from the negative (-) battery terminal.
Measure the resistance according to the value(s) in the table below.
Standard Resistance | ||||||
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Result | ||||||||||||
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B |
GO TO OPEN IN CAN MAIN BUS LINE (LHD Models) Click here |
C |
GO TO OPEN IN CAN MAIN BUS LINE (RHD Models) Click here |
D |
GO TO SHORT IN CAN BUS LINES (LHD Models) Click here |
E |
GO TO SHORT IN CAN BUS LINES (RHD Models) Click here |
A |
CHECK FOR SHORT TO GND IN V BUS (CANH, CANL - CG)
*1 | DLC3 |
Measure the resistance according to the value(s) in the table below.
Standard Resistance | |||||||||
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Result | ||||||||
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|
B |
GO TO SHORT TO GND IN CAN BUS LINE (LHD Models) Click here |
C |
GO TO SHORT TO GND IN CAN BUS LINE (RHD Models) Click here |
A |
CHECK FOR SHORT TO +B IN V BUS (CANH, CANL - BAT)
*1 | DLC3 |
Measure the resistance according to the value(s) in the table below.
Standard Resistance | |||||||||
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Result | ||||||||
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|
B |
GO TO SHORT TO +B IN CAN BUS LINE (LHD Models) Click here |
C |
GO TO SHORT TO +B IN CAN BUS LINE (RHD Models) Click here |
A |
CHECK RESULT OF COMMUNICATION BUS CHECK (CONNECTION STATUS CHECK USING INTELLIGENT TESTER)
Inspect or repair the probable malfunctioning part based on the check result of step 6 (the step in which Communication Bus Check was performed).
Result of Communication Bus Check (Connection Status Check Using Intelligent Tester) | ||||||||||||||
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Note
*: In this case, as the main body ECU (multiplex network body ECU) (Main Body) outputs communication DTCs (DTCs that start with U), the problem area can be determined from those DTCs.
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 intelligent tester. This is not a malfunction. (This occurs when optional devices are not on a sub bus that is monitored by a gateway function equipped ECU.)
Tech Tips
Regarding Communication Bus Check, refer to How to Interpret CAN Bus Diagnosis (Communication Bus Check) Screen Click here.
If the detection status of ECUs changes during the inspection, one of the branch lines of a connected ECU or sensor may be open. (Signals from the ECU or sensor that has an open in one of its branch lines create electrical noise, affecting response to the intelligent tester and whether or not the ECUs and sensors are displayed.)
Regarding the ECUs connected to sub bus 1, the main body ECU (multiplex network body ECU) displays communicating ECUs on the intelligent tester. If the communication between the main body ECU (multiplex network body ECU) and an ECU stops for 10 seconds or more, the ECU will no longer be displayed on the intelligent tester.
Regarding the communication stop mode for ECUs connected to sub bus 1, refer to the inspection procedure for the DTCs that indicate a communication stop.
B |
GO TO U1002 (Main Body) Click here |
C |
GO TO MAIN BODY ECU COMMUNICATION STOP MODE Click here |
D |
GO TO COMMUNICATION STOP MODE TABLE Click here |
E |
GO TO DIAGNOSTIC TROUBLE CODE CHART Click here |
F |
GO TO OPEN IN ONE SIDE OF CAN BRANCH LINE Click here |
A |
CHECK RESULT OF CHECK COMMUNICATION MALFUNCTION DTCs (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).
Check Result of Communication Malfunction DTC (Select Malfunctioning Bus) | ||||||||
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Tech Tips
The term ''sub bus monitor ECU'' refers to a gateway function equipped ECU that is able to monitor a bus and store DTCs.
When checking for communication DTCs, refer to How to Interpret Communication DTCs (DTCs that start with U) Click here.
Because a gateway function equipped ECU (sub bus monitor ECU) monitors signals from all ECUs that are connected to its sub bus, a gateway function equipped ECU can detect ECUs with a communication stop more accurately. In this case, perform troubleshooting by referring to the DTC combination table for the sub bus 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 intelligent tester, a past malfunction that is currently not occurring is suspected.
When a CAN branch of the V bus is malfunctioning, because the ECUs and sensors related to it detect the malfunction, the problem area can be determined using the combination of DTCs that are output.
When sub bus 1 is malfunctioning, the main body ECU (multiplex network body ECU) detects a communication stop for connected ECUs and a network communication error, and stores DTCs.
On the intelligent tester, the Main Body item displays the DTCs for ECUs connected to sub bus 1.
When both the sub bus monitor ECU and the ECUs connected to the V bus store communication DTCs, check and repair the corresponding sub bus first.
B |
GO TO U1002 (Main Body) Click here |
C |
GO TO DIAGNOSTIC TROUBLE CODE CHART Click here |
A |
DTC COMBINATION TABLE
Confirm the problem according to the combination of output DTCs regarding the CAN communication system Click here.
Result | Proceed to |
---|---|
Combination of DTCs is not in DTC Combination Table | A |
Combination of DTCs is in DTC Combination Table | B |
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 "Communication Bus Check" of the intelligent tester.
B |
GO TO COMMUNICATION STOP MODE TABLE Click here |
A |
IDENTIFICATION OF PROBLEM (PAST MALFUNCTION IN MAIN BUS OF V BUS)
Connect the cable to the negative (-) battery terminal.
Clear the DTCs using the intelligent tester.
Perform the tests in Symptom Simulation to check the wire harnesses and connectors including those for V bus main bus lines Click here.
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.
NEXT |
REPAIR OR REPLACEMENT
NEXT |
CONFIRMATION TEST
NEXT |
END |