Part 2

NETWORKING: CAN COMMUNICATION SYSTEM: DIAGNOSIS SYSTEM - (Continued)

7. DTC COMBINATION TABLE (OPEN IN CAN BRANCH OF V BUS, PAST COMMUNICATION ERROR)

(a) Regarding the past communication error of ECUs and sensors connected to the V bus (in this case, normal was displayed when performing the CAN bus check, but communication DTCs are output), the probable CAN branch that had a malfunction can be determined based on the following DTC combination table.

HINT
* Based on the table below and DTCs output from ECUs connected via CAN communication, the probable part for which communication stop occurred can be determined.
* Regarding an open in a CAN branch and a communication stop that is currently occurring, the malfunctioning part can be confirmed easily by performing the CAN bus check using the Techstream because the ECU or sensor connected to the CAN branch does not respond (the ECU or sensor name will not be displayed on the screen).
* 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 the CAN bus occurs, DTCs of almost all ECUs (or 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 How to Proceed With Troubleshooting.
* 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.

V Bus (Open in one CAN branch line)

HINT
* o: Set
* X: Not set or may be set according to the malfunctioning part when one line of a CAN branch is open.
* -: DTC is not output.
* *1: for Radio and display type (w/o Intuitive parking assist system)
* *2: for Navigation receiver type
* *3: for Radio and display type (w/ Intuitive parking assist system)

V Bus (Open in both CAN branch lines)

HINT
* o: Set
* -: DTC is not output.
* *1: for Radio and display type (w/o Intuitive parking assist system)
* *2: for Navigation receiver type
* *3: for Radio and display type (w/ Intuitive parking assist system)

8. DTC COMBINATION TABLE (OPEN IN CAN BRANCH OF SUB BUS 11, PAST COMMUNICATION ERROR) (W/ BLIND SPOT MONITOR SYSTEM)

(a) Regarding a past communication error of ECUs and sensors connected to Sub Bus 11 (in this case, normal was displayed when performing the CAN bus check, but communication DTCs are output), determine the part that had a malfunction based on DTCs output from the power management control ECU.

HINT
* As gateway function equipped ECUs (sub bus monitor ECU) monitor signals from all ECUs that are connected to sub buses, gateway function equipped ECUs can detect ECUs with a communication stop more accurately.
* DTCs output from ECUs other than the power management control ECU (gateway function equipped ECU) are shown only as a reference.
* Regarding a communication stop that is currently occurring in Sub Bus 11, the malfunctioning part can be confirmed easily by performing the CAN bus check using the Techstream.
* 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.

Sub Bus 11 (Open in one CAN branch line) / Sub Bus 11 (Open in both CAN branch lines)

HINT
* o: Set
* -: DTC is not output.
* *1: for Radio and display type (w/o Intuitive parking assist system)
* *2: for Navigation receiver type
* *3: for Radio and display type (w/ Intuitive parking assist system)

9. DTC COMBINATION TABLE (OPEN IN CAN BRANCH OF SUB BUS 15, PAST COMMUNICATION ERROR)

(a) Regarding the past communication error of ECUs connected to the sub bus 15 (in this case, normal was displayed when performing the communication bus check, but communication DTCs are output), the probable area that had a malfunction can be determined based on the following DTC combination table.

HINT
* Based on the table below and DTCs output from ECUs connected via CAN communication, the probable part for which communication stop occurred can be determined.
* Regarding an open in a CAN branch and a communication stop that is currently occurring, the malfunctioning part can be confirmed easily by performing the CAN bus check using the Techstream because the ECU or sensor connected to the CAN branch does not respond (the ECU or sensor name will not be displayed on the screen).
* 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.

Sub Bus 15 (Open in one CAN branch line) / Sub Bus 15 (Open in both CAN branch lines) / Sub Bus 15 (Open in one CAN main bus line)

HINT
* This waveform is measured between terminals CANH and GND, and terminals CANL and GND of the DLC3. (Use this as a reference for diagnosis of CAN communication lines.)
* When malfunctions in multiple ECUs are suspected based on the CAN Bus Check and DTCs checked using the Techstream, check the resistance of the CAN bus using an ohmmeter first How to Proceed With Troubleshooting. If no problems are found, check the following waveforms.
* If a waveform is not similar to one of the following 3 patterns (Group 1), then an open in a CAN main bus line, an open in a CAN branch line, or a short between a CAN line (CANH or CANL) and ground is suspected (Group 2).
* Wiggle the connector and wire harness to check if the waveform changes.

(a) CAN bus waveforms (Group 1)

(1) Normal waveform

(2) Open in both of the lines (CANH and CANL) of a CAN branch

HINT
* Waveforms (waveforms shown using dotted lines) are not present from an ECU or sensor connected to a CAN branch with an open circuit in both lines. (Waveforms from other ECUs or sensors are normal.)
* Because this waveform is similar to a normal waveform, instead of using the waveform, the malfunctioning part can be narrowed down by performing a CAN bus check.

(3) Short between the CAN bus lines (CANH and CANL)

HINT
* Waveforms disappear.
* If the malfunction is in an ECU, disconnecting the ECU will change the waveform. If the waveform does not change, a malfunction in the wire harness is suspected.

(b) CAN bus waveforms (reference) (Group 2)

NOTICE:
The following CAN bus waveforms can be used only as reference. The actual measured waveform may differ significantly depending on the location of the open or short circuit.

(1) Open in a CAN branch line (CANH)

HINT
* An abnormal waveform is output from an ECU with an open in one of its CAN branch lines. Because this abnormal output interferes with the signals from other ECUs, the output of other ECUs will also appear abnormal.
* Narrow down the malfunctioning part by checking DTCs or performing a CAN bus check, or by checking waveform changes when ECUs or sensors are disconnected. The waveform will change to one for an open in both sides of a CAN branch when the ECU or sensor with an open CAN branch line is disconnected.

(2) Open in a CAN branch line (CANL)

HINT
* Waveforms of ECUs or sensors that are nearer to the DLC3 than the open part are almost normal.
* Waveforms of ECUs or sensors that are on the opposite side of the DLC3 from the open part are abnormal.
* An open in a CAN main bus line can be confirmed by measuring the resistance between the CANH and CANL terminals of any CAN branch.

(4) Short between a CAN bus line (CANH) and ground

HINT
* Narrow down the shorted part by checking for waveform changes when disconnecting connectors from the CAN junction connector or when disconnecting ECUs or sensors.
* A short to ground in the CANH line can be confirmed by measuring the resistance between CANH and ground using an ohmmeter.

(5) Short between a CAN bus line (CANL) and ground

HINT
* Narrow down the shorted part by checking for waveform changes when disconnecting connectors from the CAN junction connector or when disconnecting ECUs or sensors.
* A short to ground in the CANL line can be confirmed by measuring the resistance between CANL and ground using an ohmmeter.