Diagnosis Item 6: Diagnose shorts in the power supply to CAN bus line (SUB).



caution When servicing a CAN bus line, earth yourself by touching a metal object such as an unpainted water pipe. If you fail to do, a component connected to the CAN bus line may be broken.

TROUBLE JUDGEMENT CONDITIONS


The M.U.T.-III judges the trouble when it is impossible to receive the periodically sent data and the voltage of CAN_H or CAN_L line is more than 4.0 V.

TROUBLESHOOTING HINTS




DIAGNOSIS PROCEDURE


STEP 1. Check the CAN bus lines. Voltage measurement at gateway-ECU connector.


caution
  • A digital multimeter should be used. For details refer to service precautions.
  • The test wiring harness should be used. For details refer to service precautions.
note This inspection allows you to check that there is a short to power supply in either CAN_H line or CAN_L line. Thus, in the following steps, check the CAN bus line that is defective.
(1)Disconnect A/C-ECU connector and gateway-ECU connector, and measure the voltage at the harness side of gateway-ECU connector.
(2)Connect the negative battery terminal, and turn the ignition switch to the "ON" position.
(3)Voltage between gateway-ECU connector terminal No.6 (CAN_H) and body earth.
OK: 4.0 V or less
(4)Voltage between gateway-ECU connector terminal No.5 (CAN_L) and body earth.
OK: 4.0 V or less
(5)Disconnect the negative battery terminal.

Q. Is the check result normal?

<Both of the measurement results show 4.0 V or less> Go to Step 13.
<Either of CAN_H line or CAN_L line the measurement results show more than 4.0 V> Go to Step 2.

STEP 2. Check the CAN line between joint connector (CAN4) and the gateway-ECU. Voltage measurement at joint connector (CAN4).


caution
  • A digital multimeter should be used. For details refer to service precautions.
  • The test wiring harness should be used. For details refer to service precautions.
  • Strictly observe the specified wiring harness repair procedure. For details refer to service precautions.
(1)Disconnect joint connector (CAN4), and measure at the wiring harness side.
(2)Connect the negative battery terminal, and turn the ignition switch to the "ON" position.
(3)Voltage between joint connector (CAN4) terminal No.10 (CAN_H) and body earth.
OK: 4.0 V or less
(4)Voltage between joint connector (CAN4) terminal No.21 (CAN_L) and body earth.
OK: 4.0 V or less
(5)Disconnect the negative battery terminal.

Q. Is the check result normal?

YES <Vehicles with headlamp automatic levelling system> : <4.0 V or less> Go to Step 3.
YES <Vehicles without headlamp automatic levelling system> : <4.0 V or less> Go to Step 6.
NO : <More than 4.0 V> Repair the wiring harness between joint connector (CAN4) and the gateway-ECU connector.

STEP 3. Check the CAN line between joint connector (CAN4) and the headlamp automatic levelling-ECU. Voltage measurement at joint connector (CAN4).


caution
  • A digital multimeter should be used. For details refer to service precautions.
  • The test wiring harness should be used. For details refer to service precautions.
(1)Disconnect joint connector (CAN4), and measure at the wiring harness side.
(2)Connect the negative battery terminal, and turn the ignition switch to the "ON" position.
(3)Voltage between joint connector (CAN4) terminal No.1 (CAN_H) and body earth.
OK: 4.0 V or less
(4)Voltage between joint connector (CAN4) terminal No.12 (CAN_L) and body earth.
OK: 4.0 V or less
(5)Disconnect the negative battery terminal.

Q. Is the check result normal?

<4.0 V or less> Go to Step 6.
<More than 4.0 V> Go to Step 4.

STEP 4. M.U.T.-III CAN bus diagnostics [Headlamp automatic levelling-ECU connector disconnected]


(1)Disconnect headlamp automatic levelling-ECU connector, and diagnose by using the M.U.T.-III.

(2)Diagnose CAN bus lines, and check if M.U.T.-III screen is as shown in the illustration.

Q. Does M.U.T.-III screen correspond to the illustration?

Repair the wiring harness between joint connector (CAN4) and the headlamp automatic levelling-ECU connector.

Check the headlamp automatic levelling-ECU connector, and repair if necessary. If the headlamp automatic levelling-ECU connector is in good condition, go to Step 5.

STEP 5. M.U.T.-III CAN bus diagnostics (retest the system)


Diagnose CAN bus lines, and check if M.U.T.-III screen shows normal state.

Q. Is the check result normal?

The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction).
Check the headlamp automatic levelling-ECU connector, and repair if necessary. If the headlamp automatic levelling-ECU connector is in good condition, replace the headlamp automatic levelling-ECU (Refer to GROUP 54A - Headlamp Automatic Levelling System, Headlamp Automatic Levelling-ECU).

STEP 6. Check the CAN line between joint connector (CAN4) and the gateway-ECU (for smartphone link display audio). Voltage measurement at joint connector (CAN4).


caution
  • A digital multimeter should be used. For details refer to service precautions.
  • The test wiring harness should be used. For details refer to service precautions.
(1)Disconnect joint connector (CAN4), and measure at the wiring harness side.
(2)Connect the negative battery terminal, and turn the ignition switch to the "ON" position.
(3)Voltage between joint connector (CAN4) terminal No. 2 (CAN_H) and body earth.
OK: 4.0 V or less
(4)Voltage between joint connector (CAN4) terminal No. 13 (CAN_L) and body earth.
OK: 4.0 V or less
(5)Disconnect the negative battery terminal.

Q. Is the check result normal?

YES <Vehicles with multi around monitor system> : <4.0 V or less> Go to Step 9.
YES <Vehicles without multi around monitor system> : <4.0 V or less> Go to Step 12.
<More than 4.0 V> Go to Step 7.

STEP 7. M.U.T.-III CAN bus diagnostics [Gateway-ECU (for smartphone link display audio) connector disconnected]


(1)Disconnect gateway-ECU (for smartphone link display audio) connector, and diagnose by using the M.U.T.-III.

(2)Diagnose CAN bus lines, and check if M.U.T.-III screen is as shown in the illustration.

Q. Does M.U.T.-III screen correspond to the illustration?

Repair the wiring harness between joint connector (CAN4) and the gateway-ECU (for smartphone link display audio) connector.

Check the gateway-ECU (for smartphone link display audio) connector, and repair if necessary. If the gateway-ECU (for smartphone link display audio) connector is in good condition, go to Step 8.

STEP 8. M.U.T.-III CAN bus diagnostics (retest the system)


Diagnose CAN bus lines, and check if M.U.T.-III screen shows normal state.

Q. Is the check result normal?

The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction).
Check the gateway-ECU (for smartphone link display audio) connector, and repair if necessary. If the gateway-ECU (for smartphone link display audio) connector is in good condition, replace the gateway-ECU (for smartphone link display audio) (Refer to GROUP 54A - Smartphone Link Display Audio ).

STEP 9. Check the CAN line between joint connector (CAN4) and the camera-ECU. Voltage measurement at joint connector (CAN4).


caution
  • A digital multimeter should be used. For details refer to service precautions.
  • The test wiring harness should be used. For details refer to service precautions.
(1)Disconnect joint connector (CAN4), and measure at the wiring harness side.
(2)Connect the negative battery terminal, and turn the ignition switch to the "ON" position.
(3)Voltage between joint connector (CAN4) terminal No.3 (CAN_H) and body earth.
OK: 4.0 V or less
(4)Voltage between joint connector (CAN4) terminal No.14 (CAN_L) and body earth.
OK: 4.0 V or less
(5)Disconnect the negative battery terminal.

Q. Is the check result normal?

<4.0 V or less> Go to Step 12.
<More than 4.0 V> Go to Step 10.

STEP 10. M.U.T.-III CAN bus diagnostics [Camera-ECU connector disconnected]


(1)Disconnect camera-ECU connector, and diagnose by using the M.U.T.-III.

(2)Diagnose CAN bus lines, and check if M.U.T.-III screen is as shown in the illustration.

Q. Does M.U.T.-III screen correspond to the illustration?

Repair the wiring harness between joint connector (CAN4) and the camera-ECU connector.

Check the camera-ECU connector, and repair if necessary. If the camera-ECU connector is in good condition, go to Step 11.

STEP 11. M.U.T.-III CAN bus diagnostics (retest the system)


Diagnose CAN bus lines, and check if M.U.T.-III screen shows normal state.

Q. Is the check result normal?

The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction).
Check the camera-ECU connector, and repair if necessary. If the camera-ECU connector is in good condition, replace the camera-ECU (Refer to GROUP 54A - Multi Around Monitor, Camera-ECU).

STEP 12. Check the CAN line between joint connector (CAN4) and the A/C-ECU. Voltage measurement at joint connector (CAN4).


caution
  • A digital multimeter should be used. For details refer to service precautions.
  • The test wiring harness should be used. For details refer to service precautions.
  • Strictly observe the specified wiring harness repair procedure. For details refer to service precautions.
(1)Disconnect joint connector (CAN4), and measure at the wiring harness side.
(2)Connect the negative battery terminal, and turn the ignition switch to the "ON" position.
(3)Voltage between joint connector (CAN4) terminal No.11 (CAN_H) and body earth.
OK: 4.0 V or less
(4)Voltage between joint connector (CAN4) terminal No.22 (CAN_L) and body earth.
OK: 4.0 V or less
(5)Disconnect the negative battery terminal.

Q. Is the check result normal?

<4.0 V or less> Repair joint connector (CAN4).
NO : <More than 4.0 V> Repair the wiring harness between joint connector (CAN4) and the A/C-ECU connector.

STEP 13. M.U.T.-III CAN bus diagnostics [A/C-ECU connector disconnected]


(1)Disconnect A/C-ECU connector and diagnose by using the M.U.T.-III.

(2)Diagnose CAN bus lines, and check if M.U.T.-III screen is as shown in the illustration.

Q. Does M.U.T.-III screen correspond to the illustration?

Go to Step 15.

Check the A/C-ECU connector, and repair if necessary. If the A/C-ECU connector is in good condition, go to Step 14.

STEP 14. M.U.T.-III CAN bus diagnostics (retest the system)


Diagnose CAN bus lines, and check if M.U.T.-III screen shows normal state.

Q. Is the check result normal?

The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction).
Check the A/C-ECU connector, and repair if necessary. If the A/C-ECU connector is in good condition, replace the A/C-ECU (Refer to GROUP 55B - Heater Control Unit).

STEP 15. M.U.T.-III CAN bus diagnostics [Gateway-ECU connector disconnected]


(1)Disconnect gateway-ECU connector, and diagnose by using the M.U.T.-III.

(2)Diagnose CAN bus lines, and check if M.U.T.-III screen is as shown in the illustration.

Q. Does M.U.T.-III screen correspond to the illustration?

The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction).

Check the gateway-ECU connector, and repair if necessary. If the gateway-ECU connector is in good condition, go to Step 16.

STEP 16. M.U.T.-III CAN bus diagnostics (retest the system)


Diagnose CAN bus lines, and check if M.U.T.-III screen shows normal state.

Q. Is the check result normal?

The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction).
Check the gateway-ECU connector, and repair if necessary. If the gateway-ECU connector is in good condition, replace the gateway-ECU.