How to Proceed With Troubleshooting
NETWORKING: CAN COMMUNICATION SYSTEM: HOW TO PROCEED WITH TROUBLESHOOTING
1. PRECAUTIONS WHEN TROUBLESHOOTING
NOTICE:
* 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 Electronic Circuit Inspection Procedure.
* 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 power 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 (-) auxiliary battery terminal and leave the vehicle for 1 minute or more before measuring the resistance.
* After turning the power switch off, waiting time may be required before disconnecting the cable from the negative (-) auxiliary battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) auxiliary battery terminal notices before proceeding with work Service Precautions.
(a) 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.
(b) The DLC3 branch and V bus main bus circuits can be checked for malfunctions by inspecting at the DLC3 terminals using a electrical tester.
NOTICE:
* 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.
(c) 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 Techstream. (This inspection is possible when the DLC3 branch and V bus main bus lines are normal.)
(d) 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.
(e) A malfunction of sub bus 15 can be determined based on the number of DTCs stored by the ECM, power management control ECU and brake booster with master cylinder assembly (skid control ECU).
(f) 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.
HINT
On the Techstream, gateway function equipped ECUs display DTCs for ECUs connected to the sub bus.
(g) 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.
(h) When a connector is disconnected, check that the terminals and connector body are not cracked, deformed or corroded.
1. VEHICLE BROUGHT TO WORKSHOP
HINT
* If the power switch can be turned on (IG) (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 power switch off until the inspection of the vehicle is finished, as some fail-safe functions are canceled when the power switch is turned off.
* If the power switch cannot be turned on (IG) (the power source mode cannot be changed to on (IG)) when the vehicle is brought in, measure the voltage of the auxiliary battery. If the voltage is below 11 V, recharge or replace the auxiliary battery before performing troubleshooting.
* If the power switch cannot be turned on (IG) even though the auxiliary battery voltage is normal, repair this malfunction before performing troubleshooting Problem Symptoms Table.
NEXT -- Continue to next step.
2. CUSTOMER PROBLEM ANALYSIS
HINT
* 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.)
(a) 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.
HINT
* 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: power switch was turned off)
Points to be confirmed
NEXT -- Continue to next step.
3. CHECK TECHSTREAM OPERATION
HINT
Read the Techstream operators manual before use General Information.
(a) Connect the Techstream to the DLC3.
(b) Turn the power switch on (IG).
(c) Turn the Techstream on.
(d) Check that the Techstream and ECUs can communicate with the power switch on (IG).
HINT
* If communication is impossible, the Techstream screen will indicate an error.
* If communication between the Techstream and ECUs is impossible, either the Techstream or vehicle has a malfunction.
* When communication between the Techstream and the vehicle is impossible, but communication is possible when the Techstream 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 auxiliary battery voltage (11 V or more).
* If communication between the Techstream and ECUs is still impossible even when the Techstream is connected to another vehicle, the Techstream has the malfunction. Perform the self tests described in the Techstream operators manual. (The Techstream may be malfunctioning or its battery may be discharged.)
B -- Go to step 7
C -- Refer to Techstream operator's manual
A -- Continue to next step.
4. CHECK DTC
(a) Using the Techstream, perform Health Check to read current and history DTCs and record them.
NOTICE:
* 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, the sensor itself also cause these DTCs to be output.
* If a CAN communication line connector is disconnected with the power switch on (IG), the ECUs of the corresponding system and related systems store a DTC.
HINT
* 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 Techstream 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 Techstream.
(b) Read the freeze frame data using the Techstream and record it.
NEXT -- Continue to next step.
5. CHECK COMMUNICATION MALFUNCTION CHECK (CONNECTION STATUS CHECK USING TECHSTREAM)
(a) Select "Communication Malfunction Check" from the screen on the Techstream.
(b) Record all the DTCs stored for ECUs and sensors.
NEXT -- Continue to next step.
6. CHECK CAN BUS CHECK (CONNECTION STATUS CHECK USING TECHSTREAM)
(a) Based on the vehicle equipment and specifications, confirm the systems that use CAN communication Diagnosis System.
(b) Select "CAN Bus Check" from the screen on the Techstream.
(c) Observe the screen for approximately 2 minutes to check the ECUs and sensors displayed on the screen.
NEXT -- Continue to next step.
7. CHECK DLC3 BRANCH LINE AND V BUS MAIN LINE (CANH - CANL)
NOTICE:
Before measuring the resistance of the CAN bus, turn the power 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 (-) auxiliary battery terminal and leave the vehicle for 1 minute or more before measuring the resistance.
HINT
Operating the power 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.
(a) Disconnect the cable from the negative (-) auxiliary battery terminal.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Text in Illustration
Result:
B -- GO TO OPEN IN CAN MAIN BUS LINE Open in CAN Main Bus Line
C -- GO TO SHORT IN CAN BUS LINES Check CAN Bus Lines for Short Circuit
A -- Continue to next step.
8. CHECK FOR SHORT TO GND IN V BUS (CANH, CANL - CG)
(a) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Text in Illustration
NG -- GO TO SHORT TO GND IN CAN BUS LINE Check CAN Bus Line for Short to GND
OK -- Continue to next step.
9. CHECK FOR SHORT TO +B IN V BUS (CANH, CANL - BAT)
(a) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Text in Illustration
NG -- GO TO SHORT TO +B IN CAN BUS LINE Check CAN Bus Line for Short to +B
OK -- Continue to next step.
10. CHECK RESULT OF CAN BUS CHECK (CONNECTION STATUS CHECK USING TECHSTREAM)
(a) 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 Techstream):
NOTICE:
* *: In this case, as the power management control ECU (PM1 Gateway) 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 Techstream. 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.)
HINT
* Regarding CAN Bus Check, refer to How to Interpret CAN Bus Diagnosis (CAN Bus Check) Screen Diagnosis System.
* 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 Techstream and whether or not the ECUs and sensors are displayed.)
* Regarding the ECUs connected to sub bus 11, the power management control ECU displays communicating ECUs on the Techstream. If the communication between the power management control ECU and an ECU stops for 3 seconds or more, the ECU will no longer be displayed on the Techstream.
* Regarding the ECUs connected to sub bus 15, the ECM displays communicating ECUs on the Techstream. If the communication between the ECM and an ECU stops for 3 seconds or more, the ECU will no longer be displayed on the Techstream.
* Regarding the communication stop mode for ECUs connected to sub bus 11, refer to the inspection procedure for the DTCs that indicate a communication stop.
B -- GO TO U1002 U1002
C -- GO TO U0100, U0129, U0293 CAN Communication System
D -- GO TO POWER MANAGEMENT CONTROL ECU COMMUNICATION STOP MODE Power Management Control ECU Communication Stop Mode
E -- GO TO ECM COMMUNICATION STOP MODE ECM Communication Stop Mode
F -- GO TO COMMUNICATION STOP MODE TABLE Symptom Related Diagnostic Procedures
G -- GO TO DIAGNOSTIC TROUBLE CODE CHART CAN Communication System
H -- GO TO OPEN IN ONE SIDE OF CAN BRANCH LINE Open in One Side of CAN Branch Line
A -- Continue to next step.
11. CHECK RESULT OF CHECK COMMUNICATION MALFUNCTION CHECK (SELECT THE MALFUNCTIONING BUS)
(a) 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 Check (Select Malfunctioning Bus):
HINT
* Only sub bus 11 has a sub bus monitor ECU.
* 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) Diagnosis System.
* 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 Diagnosis System.
* 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 Techstream, 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 11 is malfunctioning, the power management control ECU detects a communication stop for connected ECUs and a network communication error, and stores DTCs.
* On the Techstream, the PM1 Gateway item displays the DTCs for ECUs connected to sub bus 11.
* 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 U1002
C -- GO TO U0100, U0129, U0293 CAN Communication System
D -- GO TO DIAGNOSTIC TROUBLE CODE CHART CAN Communication System
E -- GO TO DIAGNOSTIC TROUBLE CODE CHART CAN Communication System
A -- Continue to next step.
12. DTC COMBINATION TABLE
(a) Confirm the problem according to the combination of output DTCs regarding the CAN communication system Diagnosis System.
HINT
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 "CAN Bus Check" of the Techstream.
B -- GO TO COMMUNICATION STOP MODE TABLE Symptom Related Diagnostic Procedures
A -- Continue to next step.
13. IDENTIFICATION OF PROBLEM (PAST MALFUNCTION IN MAIN BUS OF V BUS)
(a) Connect the cable to the negative (-) auxiliary battery terminal.
(b) Clear the DTCs using the Techstream.
(c) Perform the tests in Symptom Simulation to check the wire harnesses and connectors including those for V bus main bus lines How To Proceed With Troubleshooting.
(d) Based on the results of the check, inspect the parts that output DTCs to determine the malfunctioning part.
HINT
If DTCs are output, do not turn the power switch off.
NEXT -- Continue to next step.
14. REPAIR OR REPLACEMENT
NEXT -- Continue to next step.
15. CONFIRMATION TEST
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