Diagnosis Item 7: Diagnose shorts in the earth to CAN bus line (SUB). <Vehicles with Automatic A/C>

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 resistance of CAN_H or CAN_L line is less than 1.0 V.

TROUBLESHOOTING HINTS

Malfunction of the wiring harness
Malfunction of the connector
Malfunction of the gateway-ECU <Vehicles with automatic A/C>
Malfunction of the A/C-ECU <Vehicles with automatic A/C>
Malfunction of the camera-ECU <Vehicles with multi around monitor system>
Malfunction of the headlamp automatic levelling-ECU <Vehicles with auto headlamp levelling system>

DIAGNOSIS PROCEDURE

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

caution

A digital multimeter should be used. For details refer to

caution

The test wiring harness should be used. For details refer to

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 resistance at the harness side of diagnosis connector.

(2)

caution

When measuring the resistance, disconnect the negative battery terminal. For details refer to

Ensure that the negative battery terminal is disconnected.

(3)resistance between gateway-ECU connector terminal No.6 (CAN_H) and body earth.
OK: 1 kΩ or more

(4)resistance between gateway-ECU connector terminal No.5 (CAN_L) and body earth.
OK: 1 kΩ or more

Q. Is the check result normal?

	<Both of the measurement results show 1 kΩ or more> Go to Step 10.

	<Either of CAN_H line or CAN_L line the measurement results show less than 1 kΩ> Go to Step 2.

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

caution

A digital multimeter should be used. For details refer to

caution

The test wiring harness should be used. For details refer to

(1)Disconnect joint connector (CAN4), and measure at the wiring harness side.

(2)

caution

When measuring the resistance, disconnect the negative battery terminal. For details refer to

Ensure that the negative battery terminal is disconnected.

(3)resistance between joint connector (CAN4) terminal No.10 (CAN_H) and body earth.
OK: 1 kΩ or more

(4)resistance between joint connector (CAN4) terminal No.21 (CAN_L) and body earth.
OK: 1 kΩ or more

caution

Strictly observe the specified wiring harness repair procedure. For details refer to

Q. Is the check result normal?

	YES : <1 kΩ or more> Go to Step 3.

	NO : <Less than 1 kΩ> 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. resistance measurement at joint connector (CAN4).

caution

A digital multimeter should be used. For details refer to

caution

The test wiring harness should be used. For details refer to

(1)Disconnect joint connector (CAN4), and measure at the wiring harness side.

(2)

caution

When measuring the resistance, disconnect the negative battery terminal. For details refer to

Ensure that the negative battery terminal is disconnected.

(3)resistance between joint connector (CAN4) terminal No.1 (CAN_H) and body earth.
OK: 1 kΩ or more

(4)resistance between joint connector (CAN4) terminal No.12 (CAN_L) and body earth.
OK: 1 kΩ or more

Q. Is the check result normal?

	<1 kΩ or more> Go to Step 6.

	<Less than 1 kΩ > 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 levelling-ECU connector, and repair if necessary. If the headlamp levelling-ECU connector is in good condition, replace the headlamp levelling-ECU (Refer to GROUP 54A - Headlamp Automatic levelling System, Headlamp levelling-ECU ).

STEP 6. Check the CAN line between joint connector (CAN4) and the camera-ECU. resistance measurement at joint connector (CAN4).

caution

A digital multimeter should be used. For details refer to

caution

The test wiring harness should be used. For details refer to

(1)Disconnect joint connector (CAN4), and measure at the wiring harness side.

(2)

caution

When measuring the resistance, disconnect the negative battery terminal. For details refer to

Ensure that the negative battery terminal is disconnected.

(3)resistance between joint connector (CAN4) terminal No.3 (CAN_H) and body earth.
OK: 1 kΩ or more

(4)resistance between joint connector (CAN4) terminal No.14 (CAN_L) and body earth.
OK: 1 kΩ or more

Q. Is the check result normal?

	<1 kΩ or more> Go to Step 9.

	<Less than 1 kΩ > Go to Step 7.

STEP 7. 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 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 camera-ECU connector, and repair if necessary. If the camera-ECU connector is in good condition, replace the camera-ECU (Refer to GROUP 54A - Camera System, Camera-ECU ).

STEP 9. Check the CAN line between joint connector (CAN4) and the A/C-ECU. resistance measurement at joint connector (CAN4).

caution

A digital multimeter should be used. For details refer to

caution

The test wiring harness should be used. For details refer to

(1)Disconnect joint connector (CAN4), and measure at the wiring harness side.

(2)

caution

When measuring the resistance, disconnect the negative battery terminal. For details refer to

Ensure that the negative battery terminal is disconnected.

(3)resistance between joint connector (CAN4) terminal No.11 (CAN_H) and body earth.
OK: 1 kΩ or more

(4)resistance between joint connector (CAN4) terminal No.22 (CAN_L) and body earth.
OK: 1 kΩ or more

caution

Strictly observe the specified wiring harness repair procedure. For details refer to

Q. Is the check result normal?

	<1 kΩ or more> Repair joint connector (CAN4).

	NO : <Less than 1 kΩ > Repair the wiring harness between joint connector (CAN4) and the A/C-ECU connector.

STEP 10. 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 12.

Check the A/C-ECU connector, and repair if necessary. If the A/C-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 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 12. 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 13.

STEP 13. 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 (Refer to ).