Diagnosis Item 2: Diagnose shorts in the power supply to CAN bus line. <LHD>

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

Malfunction of the wiring harness
Malfunction of the connector
Malfunction of the ETACS-ECU
Malfunction of the combination meter
Malfunction of the transfer-ECU <4WD (6M/T, A/T)>
Malfunction of the A/C-ECU <Vehicles with automatic A/C>
Malfunction of the KOS&OSS-ECU <Vehicles with KOS&OSS>
Malfunction of the SRS-ECU
Malfunction of the ABS-ECU <Vehicles with ABS>
Malfunction of the ASTC-ECU <Vehicles with ASTC>
Malfunction of the steering wheel sensor <Vehicles with ASTC>
Malfunction of the A/T-ECU <A/T>
Malfunction of the engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Check the CAN bus lines. Voltage measurement at diagnosis 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 engine-ECU connector and ETACS-ECU connector, and measure the voltage at the harness side of diagnosis connector.

(2)Connect the negative battery terminal, and turn the ignition switch to the "ON" position.

(3)Voltage between diagnosis connector terminal No.6 (CAN_H) and body earth
OK: 4.0 V or less

(4)Voltage between diagnosis connector 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?

	<Both of the measurement results show 4.0 V or less> Go to Step 30.

	<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. Voltage measurement at joint connector (CAN1).

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 (CAN1), 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 (CAN1) terminal No.7 (CAN_H) and body earth
OK: 4.0 V or less

(4)Voltage between joint connector (CAN1) terminal No.18 (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 13.

	<More than 4.0 V> Go to Step 3.

STEP 3. Check the CAN line between joint connector (CAN2) and the engine-ECU. Voltage measurement at joint connector (CAN2).

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 (CAN2), 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 (CAN2) terminal No.10 (CAN_H) and body earth
OK: 4.0 V or less

(4)Voltage between joint connector (CAN2) 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 ABS or ASTC> : <4.0 V or less> Go to Step 4.

	YES <Vehicles without ABS and ASTC, and with KOS&OSS> : <4.0 V or less> Go to Step 7.

	YES <Vehicles without ABS, ASTC and KOS&OSS> : <4.0 V or less> Go to Step 10.

	NO : <More than 4.0 V> Repair the wiring harness between joint connector (CAN2) and the engine-ECU connector.

STEP 4. Check the CAN line between joint connector (CAN2) and the ABS-ECU or ASTC-ECU. Voltage measurement at joint connector (CAN2).

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 (CAN2), 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 (CAN2) terminal No.5 (CAN_H) and body earth
OK: 4.0 V or less

(4)Voltage between joint connector (CAN2) terminal No.16 (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 7.

	<More than 4.0 V> Go to Step 5.

STEP 5. M.U.T.-III CAN bus diagnostics [ABS-ECU or ASTC-ECU connector disconnected]

(1)Disconnect ABS-ECU or ASTC-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?

Check the intermediate connector, and repair if necessary. If the intermediate connector is in good condition, repair the wiring harness between joint connector (CAN2) and the ABS-ECU or ASTC-ECU connector.

Check the ABS-ECU or ASTC-ECU connector, and repair if necessary. If the ABS-ECU or ASTC-ECU connector is in good condition, go to Step 6.

STEP 6. 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 ABS-ECU or ASTC-ECU connector, and repair if necessary. If the ABS-ECU connector is in good condition, replace the ABS-ECU (Refer to GROUP 35B - Hydraulic Unit) or ASTC-ECU (Refer to GROUP 35C - Hydraulic Unit).

STEP 7. Check the CAN line between joint connector (CAN2) and the KOS&OSS-ECU. Voltage measurement at joint connector (CAN2).

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 (CAN2), 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 (CAN2) terminal No.8 (CAN_H) and body earth
OK: 4.0 V or less

(4)Voltage between joint connector (CAN2) terminal No.19 (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 10.

	<More than 4.0 V> Go to Step 8.

STEP 8. M.U.T.-III CAN bus diagnostics [KOS&OSS-ECU connector disconnected]

(1)Disconnect KOS&OSS-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 (CAN2) and the KOS&OSS-ECU connector.

Check the KOS&OSS-ECU connector, and repair if necessary. If the KOS&OSS-ECU connector is in good condition, go to Step 9.

STEP 9. 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 KOS&OSS-ECU connector, and repair if necessary. If the KOS&OSS-ECU connector is in good condition, replace the KOS&OSS-ECU (Refer to GROUP 42B - KOS&OSS-ECU).

STEP 10. Check the CAN line between joint connector (CAN2) and the SRS-ECU. Voltage measurement at joint connector (CAN2).

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 (CAN2), 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 (CAN2) terminal No.7 (CAN_H) and body earth
OK: 4.0 V or less

(4)Voltage between joint connector (CAN2) terminal No.18 (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 the wiring harness between joint connector (CAN2) and the joint connector (CAN1).

	<More than 4.0 V> Go to Step 11.

STEP 11. M.U.T.-III CAN bus diagnostics [SRS-ECU connector disconnected]

(1)Disconnect SRS-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 (CAN2) and the SRS-ECU connector.

Check the SRS-ECU connector, and repair if necessary. If the SRS-ECU connector is in good condition, go to Step 12.

STEP 12. 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 SRS-ECU connector, and repair if necessary. If the SRS-ECU connector is in good condition, replace the SRS-ECU (Refer to GROUP 52B - SRS-ECU).

STEP 13. Check the CAN line between joint connector (CAN1) and the ETACS-ECU. Voltage measurement at joint connector (CAN1).

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 (CAN1), 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 (CAN1) terminal No.11 (CAN_H) and body earth
OK: 4.0 V or less

(4)Voltage between joint connector (CAN1) 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?

	YES <Vehicles with automatic A/C> : <4.0 V or less> Go to Step 14.

	YES <Vehicles without automatic A/C [4WD (6M/T, A/T)]> : <4.0 V or less> Go to Step 17.

	YES <Vehicles without automatic A/C (2WD-A/T)> : <4.0 V or less> Go to Step 20.

	YES <Vehicles without automatic A/C (2WD-M/T, 4WD-5M/T)> : <4.0 V or less> Go to Step 23.

	NO : <More than 4.0 V> Repair the wiring harness between joint connector (CAN1) and the ETACS-ECU connector.

STEP 14. Check the CAN line between joint connector (CAN1) and the A/C-ECU. Voltage measurement at joint connector (CAN1).

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 (CAN1), 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 (CAN1) terminal No.5 (CAN_H) and body earth
OK: 4.0 V or less

(4)Voltage between joint connector (CAN1) terminal No.16 (CAN_L) and body earth
OK: 4.0 V or less

(5)Disconnect the negative battery terminal.

Q. Is the check result normal?

	YES <4WD (6M/T, A/T)> : <4.0 V or less> Go to Step 17.

	YES <2WD-A/T> : <4.0 V or less> Go to Step 20.

	YES <2WD-M/T, 4WD-5M/T> : <4.0 V or less> Go to Step 23.

	NO : <More than 4.0 V> Go to Step 15.

STEP 15. 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?

Repair the wiring harness between joint connector (CAN1) and the A/C-ECU connector.

Check the A/C-ECU connector, and repair if necessary. If the A/C-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 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 17. Check the CAN line between joint connector (CAN1) and the transfer-ECU. Voltage measurement at joint connector (CAN1).

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 (CAN1), 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 (CAN1) terminal No.4 (CAN_H) and body earth
OK: 4.0 V or less

(4)Voltage between joint connector (CAN1) terminal No.15 (CAN_L) and body earth
OK: 4.0 V or less

(5)Disconnect the negative battery terminal.

Q. Is the check result normal?

	YES <A/T> : <4.0 V or less> Go to Step 20.

	YES <M/T> : <4.0 V or less> Go to Step 23.

	<More than 4.0 V> Go to Step 18.

STEP 18. M.U.T.-III CAN bus diagnostics [transfer-ECU connector disconnected]

(1)Disconnect transfer-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 (CAN1) and the transfer-ECU connector.

Check the transfer-ECU connector, and repair if necessary. If the transfer-ECU connector is in good condition, go to Step 19.

STEP 19. 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 transfer-ECU connector, and repair if necessary. If the transfer-ECU connector is in good condition, replace the transfer-ECU (Refer to GROUP 22A - Transfer-ECU <M/T> or GROUP 23A - Transfer-ECU <A/T>).

STEP 20. Check the CAN line between joint connector (CAN1) and the A/T-ECU. Voltage measurement at joint connector (CAN1).

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 (CAN1), 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 (CAN1) terminal No.1 (CAN_H) and body earth
OK: 4.0 V or less

(4)Voltage between joint connector (CAN1) 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 23.

	<More than 4.0 V> Go to Step 21.

STEP 21. M.U.T.-III CAN bus diagnostics [A/T-ECU connector disconnected]

(1)Disconnect A/T-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 (CAN1) and the A/T-ECU connector.

Check the A/T-ECU connector, and repair if necessary. If the A/T-ECU connector is in good condition, go to Step 22.

STEP 22. 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/T-ECU connector, and repair if necessary. If the A/T-ECU connector is in good condition, replace the A/T-ECU (Refer to GROUP 23A - A/T-ECU).

STEP 23. Check the CAN line between joint connector (CAN1) and the combination meter. Voltage measurement at joint connector (CAN1).

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 (CAN1), 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 (CAN1) terminal No.2 (CAN_H) and body earth
OK: 4.0 V or less

(4)Voltage between joint connector (CAN1) 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 ASTC> : <4.0 V or less> Go to Step 26.

	YES <Vehicles without ASTC> : <4.0 V or less> Go to Step 29.

	<More than 4.0 V> Go to Step 24.

STEP 24. M.U.T.-III CAN bus diagnostics [combination meter connector disconnected]

(1)Disconnect combination meter 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 (CAN1) and the combination meter connector.

Check the combination meter connector, and repair if necessary. If the combination meter connector is in good condition, go to Step 25.

STEP 25. 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 combination meter connector, and repair if necessary. If the combination meter connector is in good condition, replace the combination meter (Refer to GROUP 54A - Combination meter).

STEP 26. Check the CAN line between joint connector (CAN1) and the steering wheel sensor. Voltage measurement at joint connector (CAN1).

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 (CAN1), 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 (CAN1) terminal No.6 (CAN_H) and body earth
OK: 4.0 V or less

(4)Voltage between joint connector (CAN1) terminal No.17 (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 29.

	<More than 4.0 V> Go to Step 27.

STEP 27. M.U.T.-III CAN bus diagnostics [steering wheel sensor connector disconnected]

(1)Disconnect steering wheel sensor 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 (CAN1) and the steering wheel sensor connector.

Check the steering wheel sensor connector, and repair if necessary. If the steering wheel sensor connector is in good condition, go to Step 28.

STEP 28. 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 steering wheel sensor connector, and repair if necessary. If the steering wheel sensor connector is in good condition, replace the steering wheel sensor (Refer to GROUP 35C - Steering Wheel Sensor).

STEP 29. Check the CAN line between joint connector (CAN1) and the diagnosis connector. Voltage measurement at joint connector (CAN1).

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 (CAN1), 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 (CAN1) terminal No.10 (CAN_H) and body earth
OK: Less than 1.0 V

(4)Voltage between joint connector (CAN1) terminal No.21 (CAN_L) and body earth
OK: Less than 1.0 V

(5)Disconnect the negative battery terminal.

Q. Is the check result normal?

	<Less than 1.0 V> The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction).

	<1.0 V or more> Repair the diagnosis connector, or the wiring harness between joint connector (CAN1) and the diagnosis connector.

STEP 30. M.U.T.-III CAN bus diagnostics [engine-ECU connector disconnected]

(1)Disconnect engine-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 32.

Check the engine-ECU connector, and repair if necessary. If the engine-ECU connector is in good condition, go to Step 31.

STEP 31. 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 engine-ECU connector, and repair if necessary. If the engine-ECU connector is in good condition, replace the engine-ECU (Refer to GROUP 13A - Engine-ECU <4G6>, GROUP 13B - Engine-ECU <4D5> or GROUP 13C - Engine-ECU <4N1>).

STEP 32. M.U.T.-III CAN bus diagnostics [ETACS-ECU connector disconnected]

(1)Disconnect ETACS-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 ETACS-ECU connector, and repair if necessary. If the ETACS-ECU connector is in good condition, go to Step 33.

STEP 33. 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 ETACS-ECU connector, and repair if necessary. If the ETACS-ECU connector is in good condition, replace the ETACS-ECU (Refer to GROUP 54A - ETACS, ETACS-ECU).