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.
* 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.

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: Gateway function equipped ECUs relay signals between the ECUs connected to the different buses.
* *2: for Navigation receiver type.
* *3: for Radio and display type w/ intuitive parking assist system.
* *4: for Radio and display type w/o intuitive parking assist system.
* *5: Separate type yaw rate sensor.

HINT
* o: Set
* -: DTC is not output.
* *1: Gateway function equipped ECUs relay signals between the ECUs connected to the different buses.
* *2: for Navigation receiver type.
* *3: for Radio and display type w/ intuitive parking assist system.
* *4: for Radio and display type w/o intuitive parking assist system.
* *5: Separate type yaw rate sensor

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

(a) Regarding a past communication error of ECUs and sensors connected to sub bus 2 (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 network gateway 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 network gateway ECU (gateway function equipped ECU) are shown only as a reference.
* Regarding a communication stop that is currently occurring in sub bus 2, 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.

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 CANL line can be confirmed by measuring the resistance between CANL and ground using an ohmmeter.

10. DATA SENDING/RECEIVING TABLE

(a) Data sending/receiving table

HINT
If Data List items related to sent/received data are not displayed properly, the part for which communication is interrupted can be determined using the table below.

*1: Whether the ECU that sends data is functioning or not can be judged by using the Techstream to check items such as switches or sensors that send signals to the ECU via direct lines.

*2: Although the received contents cannot be checked in the Data List, whether or not the data is received normally can be checked by observing the combination meter.

*3: The combination meter assembly receives a vehicle speed signal from the brake actuator assembly (skid control ECU) and sends the signal to other ECUs.

(b) Details of relevant Data List items (Selected system: Engine and ECT) (for 2AR-FE)

HINT
Using the Techstream to read the Data List allows the values or states of switches, sensors, actuators and other items to be read without removing any parts. This non-intrusive inspection can be very useful because intermittent conditions or signals may be discovered before parts or wiring is disturbed. Reading the Data List information early in troubleshooting is one way to save diagnostic time.

NOTICE:
In the table below, the values listed under "Normal Condition" are reference values. Do not depend solely on these reference values when deciding whether a part is faulty or not.

HINT
Normal Condition: If no conditions are specifically stated for "idling", the shift lever should be in N or P, the A/C switch should be off and all accessory switches should be off.

(1) Warm up the engine.

(2) Turn the A/C switch off.

(3) Turn the ignition switch off.

(4) Connect the Techstream to the DLC3.

(5) Turn the ignition switch to ON.

(6) Turn the Techstream on.

(7) Enter the following menus: Powertrain / Engine and ECT / Data List.

(8) According to the display on the Techstream, read the Data List.

Engine and ECT

(c) Details of relevant Data List items (Selected system: Engine) (for 2GR-FE)

HINT
Using the Techstream to read the Data List allows the values or states of switches, sensors, actuators and other items to be read without removing any parts. This non-intrusive inspection can be very useful because intermittent conditions or signals may be discovered before parts or wiring is disturbed. Reading the Data List information early in troubleshooting is one way to save diagnostic time.

NOTICE:
In the table below, the values listed under "Normal Condition" are reference values. Do not depend solely on these reference values when deciding whether a part is faulty or not.

HINT
Normal Condition: If no conditions are specifically stated for "idling", the shift lever should be in N or P, the A/C switch should be off and all accessory switches should be off.

(1) Warm up the engine.

(2) Turn the A/C switch off.

(3) Turn the ignition switch off.

(4) Connect the Techstream to the DLC3.

(5) Turn the engine switch on (IG).

(6) Turn the Techstream on.

(7) Enter the following menus: Powertrain / Engine / Data List.

(8) According to the display on the Techstream, read the Data List.