Diagnosis System

CAN COMMUNICATION: CAN COMMUNICATION SYSTEM: DIAGNOSIS SYSTEM

1. CAN BUS CHECK

(a) Using the Techstream, select "CAN Bus Check" from "System Select".

2. CHECK FOR INSTALLED SYSTEMS (ECUS AND SENSORS) THAT ADOPT CAN COMMUNICATION

(a) The systems (ECUs and sensors) that adopt CAN communication vary depending on the vehicle optional equipment. Check which systems (ECUs and sensors) are installed on the vehicle.

3. DTC TABLE BY ECU

NOTICE:
If system function temporarily returns to normal, DTCs may not be output again even though the following DTC reproduction methods are used.

HINT
If CAN communication system DTCs are output, trouble cannot be determined only by the DTCs. Perform troubleshooting according to "HOW TO PROCEED WITH TROUBLESHOOTING" How to Proceed With Troubleshooting.

(a) ECM / Techstream display: "Engine"

HINT
DTC communication uses the CAN communication system.

ECM / Techstream display: "Engine"

*: The ECM is malfunctioning if U0101 is output. Replace the ECM.

(b) ECM / Techstream display: "ECT"

HINT
DTC communication uses the CAN communication system.

ECM / Techstream display: "ECT"

*: The ECM is malfunctioning if U0100 is output. Replace the ECM.

(c) SKID CONTROL ECU / Techstream display: "ABS/ VSC/TRAC"

HINT
DTC communication uses the CAN communication system.

SKID CONTROL ECU / Techstream display: "ABS/ VSC/TRAC"

(d) POWER STEERING ECU / Techstream display: "EPS"

HINT
DTC communication uses the CAN communication system.

POWER STEERING ECU / Techstream display: "EPS"

(e) 4WD CONTROL ECU / Techstream display: "Four Wheel Drive Control"

HINT
DTC communication uses the CAN communication system.

4WD CONTROL ECU / Techstream display: "Four Wheel Drive Control"

(f) NAVIGATION ECU/Techstream display "AVN1"

HINT
DTC communication uses the CAN communication system.

DISPLAY AND NAVIGATION MODULE DISPLAY/Techstream display "AVN1"

(g) GATEWAY ECU

HINT
The gateway ECU is connected to the CAN communication system, but CAN communication DTCs are not output.

(h) CENTER AIRBAG SENSOR

HINT
The center airbag sensor is connected to the CAN communication system, but CAN communication DTCs are not output.

4. DTC COMBINATION TABLE

HINT
The probable part for which communication is interrupted can be determined using the table below and comparing the DTCs output from ECUs connected to the CAN communication system.

HINT
* o: Set
* X: Not set or may be set according to the malfunctioning part when one side of a CAN branch line is open.
* [Square]: DTC is stored while the engine switch is on (IG) when a malfunction is detected. (DTC will remain stored if engine switch remains on (IG), even if malfunction returns to normal. The DTC will be cleared when the engine switch is turned off. )
* 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 6 to 8) 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.
* *1: Only stored when communication has recovered. During communication stop, DTC cannot be stored.

5. 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 assumed using the table below.

* [Black Circle]: Detects (and sends)

* o: Receives

*1: Observing the values on the Techstream can help to determine whether or not the ECU is functioning normally.

(b) Details of relevant Data List items (Selected system: Engine)

(1) Turn the engine switch off.

(2) Connect Techstream to the DLC3.

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

(4) Turn the tester on.

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

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

Engine

(c) Details of relevant Data List items (Selected system: ABS/VSC/TRAC)

(1) Turn the engine switch off.

(2) Connect Techstream to the DLC3.

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

(4) Turn the tester on.

(5) Enter the following menus: Chassis / ABS/VSC/TRAC / Data List.

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

ABS/VSC/TRAC

(d) Details of relevant Data List items (Selected system: EMPS)

(1) Turn the engine switch off.

(2) Connect Techstream to the DLC3.

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

(4) Turn the tester on.

(5) Enter the following menus: Chassis / EMPS / Data List.

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

EMPS

(e) Details of relevant Data List items (Selected system: 4WD)

(1) Turn the engine switch off.

(2) Connect Techstream to the DLC3.

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

(4) Turn the tester on.

(5) Enter the following menus: Powertrain / 4WD / Data List.

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

4WD

6. CAN BUS WAVEFORMS

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 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, open in a CAN branch line, or a short between a CAN line (CANH or CANL) and ground is suspected (Group 2).

(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 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.)

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

HINT
* Waveforms disappear.
* Narrow down the shorted part by checking for waveform changes when disconnecting connectors from the CAN junction connector or when disconnecting ECUs or sensors.

(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 (disconnecting connectors from the CAN junction connector enables a quick inspection). 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.

7. CONFIRMATION OF SYMPTOMS RESULTING FROM CAN COMMUNICATION ERROR

(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 or part)
* 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: Engine switch was turned off)

Points to be confirmed