54C-DIAGNOSTICS ITEM 4

Diagnostic Item 4: Diagnose shorts between CAN_H and L lines (CAN-C)

caution

When servicing a CAN bus line, ground 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.
When the ETACS-ECU of vehicles without KOS is replaced, the encrypted code of the ignition key needs to be registered to the ETACS-ECU. (If the encrypted code is not registered, the engine cannot be started. Register the encrypted code as described in GROUP 54A, Immobilizer System - How to Register Key ID .)

TROUBLE JUDGMENT

When all of the following conditions are met, the scan tool (M.U.T.-III) determines that a short circuit is present between CAN_L and CAN_H lines.

The scan tool (M.U.T.-III) cannot receive the periodic transmission data from any ECUs.
The voltage between CAN-C (CAN_L and CAN_H lines) is 1.0 V or more, 4.0 V or less.
The resistance at CAN-C (CAN_L and CAN_H lines) is 2 ohms or less.

TROUBLESHOOTING HINTS

Malfunction of the wiring harness
Malfunction of the connector
Malfunction of the ETACS-ECU
Malfunction of the gateway-ECU <Vehicles with Blind Spot Warning [BSW] (with Lane Change Assist) system>
Malfunction of the SRS-ECU
Malfunction of the column switch assembly (steering wheel sensor)
Malfunction of the electric parking brake ECU <Vehicles with electric parking brake>
Malfunction of the AWD-ECU <Vehicles without S-AWC> or AWC-ECU <Vehicles with S-AWC>
Malfunction of the FCM/LDW/AHB-ECU <Vehicles with FCM>
Malfunction of the ASC-ECU
Malfunction of the EPS-ECU
Malfunction of the transaxle control module (TCM)
Malfunction of the occupant classification-ECU
Malfunction of the ACC-ECU <Vehicles with ACC>
Malfunction of the engine control module (ECM)

DIAGNOSIS

STEP 1. Connector check: C-126 intermediate connector

caution

The strand end of the twist wire should be within 10 cm from the connector. For details refer to

Is the check result normal?

Go to Step 2

Repair the defective connector.

STEP 2. Resistance measurement at C-126 intermediate connector.

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 the connector, and measure at its female-side intermediate connector (at the front wiring harness side).

(2) Turn the ignition switch to the LOCK (OFF) position.

(3)

caution

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

Ensure that the negative battery terminal is disconnected.

(4) Resistance between C-126 intermediate connector terminal Nos.15 and 16

OK: 120 ± 20 ohms

Is the check result normal?

<Within 120 ± 20 ohms> Go to Step 17

<Not within 120 ± 20 ohms> Go to Step 3

STEP 3. Connector check: joint connector (CAN1)

caution

The strand end of the twist wire should be within 10 cm from the connector. For details refer to

When checking the joint connector, ensure that its wiring harness side and its short pins are not damaged.

Is the check result normal?

Go to Step 4

Repair a defective connector or replace the joint connector.

STEP 4. Connector check: joint connector (CAN2)

note	Step 4 is only for vehicles with ACC. On vehicles without it, go to Step 5.

caution

The strand end of the twist wire should be within 10 cm from the connector. For details refer to

When checking the joint connector, ensure that its wiring harness side and its short pins are not damaged.

Is the check result normal?

Go to Step 5

Repair a defective connector or replace the joint connector.

STEP 5. Resistance measurement at joint connector (CAN1).

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 the connector, and measure at the wiring harness side.

(2) Turn the ignition switch to the LOCK (OFF) position.

(3)

caution

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

Ensure that the negative battery terminal is disconnected.

(4) Resistance between joint connector (CAN1) terminal Nos.8 and 17

OK: 120 ± 20 ohms

Is the check result normal?

: <Within 120 ± 20 ohms> Go to Step 9

<Not within 120 ± 20 ohms> Go to Step 6

STEP 6. Resistance measurement at ECM connector.

note	Step 6 is only for vehicles without ACC. On vehicles with it, go to Step 7.

caution

A digital multimeter should be used. For details refer to

(1) Remove the ECM, and measure at the equipment side.

(2) Resistance between ECM connector terminal Nos.90 and 91

OK: 120 ± 20 ohms

caution

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

Is the check result normal?

<Within 120 ± 20 ohms> Repair the wiring harness between joint connector (CAN1) and the ECM connector.

<Not within 120 ± 20 ohms> Check the ECM connector, and repair if necessary. If the ECM connector is in good condition, replace the ECM.

STEP 7. Resistance measurement at joint connector (CAN2).

note	Step 7, 8, 9 and 10 are only for vehicles with ACC. On vehicles without it, go to Step 11.

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 the connector, and measure at the wiring harness side.

(2) Turn the ignition switch to the LOCK (OFF) position.

(3)

caution

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

Ensure that the negative battery terminal is disconnected.

(4) Resistance between joint connector (CAN2) terminal Nos.9 and 20

OK: 1 kΩ or more

Is the check result normal?

<1 kΩ or more> Go to Step 9

<Less than 1 kΩ> Go to Step 8

STEP 8. Resistance measurement at ACC-ECU connector.

caution

A digital multimeter should be used. For details refer to

(1) Remove the ACC-ECU, and measure at the equipment side.

(2) Resistance between ACC-ECU connector terminal Nos.2 and 7

OK: 1 kΩ or more

caution

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

Is the check result normal?

<1 kΩ or more> Repair the wiring harness between joint connector (CAN2) and the ACC-ECU connector.

<Less than 1 kΩ> Check the ACC-ECU connector, and repair if necessary. If the ACC-ECU connector is in good condition, replace the ACC-ECU.

STEP 9. Resistance measurement at joint connector (CAN2).

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 the connector, and measure at the wiring harness side.

(2) Turn the ignition switch to the LOCK (OFF) position.

(3)

caution

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

Ensure that the negative battery terminal is disconnected.

(4) Resistance between joint connector (CAN2) terminal Nos.10 and 21

OK: 120 ± 20 ohms

caution

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

Is the check result normal?

: <Within 120 ± 20 ohms> Check intermediate connector, and repair if necessary. If the intermediate connector is in good condition, repair the wiring harness between joint connector (CAN2) and the joint connector (CAN1).

<Not within 120 ± 20 ohms> Go to Step 10

STEP 10. Resistance measurement at ECM connector.

caution

A digital multimeter should be used. For details refer to

(1) Remove the ECM, and measure at the equipment side.

(2) Resistance between ECM connector terminal Nos.90 and 91

OK: 120 ± 20 ohms

caution

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

Is the check result normal?

<Within 120 ± 20 ohms> Repair the wiring harness between joint connector (CAN2) and the ECM connector.

<Not within 120 ± 20 ohms> Check the ECM connector, and repair if necessary. If the ECM connector is in good condition, replace the ECM.

STEP 11. Resistance measurement at joint connector (CAN1).

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 the connector, and measure at the wiring harness side.

(2) Turn the ignition switch to the LOCK (OFF) position.

(3)

caution

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

Ensure that the negative battery terminal is disconnected.

(4) Resistance between joint connector (CAN1) terminal Nos.4 and 13

OK: 1 kΩ or more

Is the check result normal?

<1 kΩ or more> Go to Step 13

<Less than 1 kΩ> Go to Step 12

STEP 12. Resistance measurement at TCM connector.

caution

A digital multimeter should be used. For details refer to

(1) Remove the TCM, and measure at the equipment side.

(2) Resistance between TCM connector terminal Nos.9 and 10 <CVT>

OK: 1 kΩ or more

(3) Resistance between TCM connector terminal Nos.10 and 11 <A/T>

OK: 1 kΩ or more

caution

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

Is the check result normal?

<1 kΩ or more> Repair the wiring harness between joint connector (CAN1) and the TCM connector.

<Less than 1 kΩ> Check the TCM connector, and repair if necessary. If the TCM connector is in good condition, replace the TCM.

STEP 13. Resistance measurement at joint connector (CAN1).

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 the connector, and measure at the wiring harness side.

(2) Turn the ignition switch to the LOCK (OFF) position.

(3)

caution

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

Ensure that the negative battery terminal is disconnected.

(4) Resistance between joint connector (CAN1) terminal Nos.6 and 15

OK: 1 kΩ or more

Is the check result normal?

<1 kΩ or more> Go to Step 15

<Less than 1 kΩ> Go to Step 14

STEP 14. Resistance measurement at EPS-ECU connector.

caution

A digital multimeter should be used. For details refer to

(1) Remove the EPS-ECU, and measure at the equipment side.

(2) Resistance between EPS-ECU connector terminal Nos.5 and 6

OK: 1 kΩ or more

caution

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

Is the check result normal?

<1 kΩ or more> Check the intermediate connector, and repair if necessary. If the intermediate connector is in good condition, repair the wiring harness between joint connector (CAN1) and the EPS-ECU connector.

<Less than 1 kΩ> Check the EPS-ECU connector, and repair if necessary. If the EPS-ECU connector is in good condition, replace the EPS-ECU.

STEP 15. Resistance measurement at joint connector (CAN1).

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 the connector, and measure at the wiring harness side.

(2) Turn the ignition switch to the LOCK (OFF) position.

(3)

caution

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

Ensure that the negative battery terminal is disconnected.

(4) Resistance between joint connector (CAN1) terminal Nos.7 and 16

OK: 1 kΩ or more

caution

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

Is the check result normal?

<1 kΩ or more> Repair the wiring harness between joint connector (CAN1) and C-126 intermediate connector.

<Less than 1 kΩ> Go to Step 16

STEP 16. Resistance measurement at ASC-ECU connector.

caution

A digital multimeter should be used. For details refer to

(1) Remove the ASC-ECU, and measure at the equipment side.

(2) Resistance between ASC-ECU connector terminal Nos.11 and 10

OK: 1 kΩ or more

caution

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

Is the check result normal?

<1 kΩ or more> Repair the wiring harness between joint connector (CAN1) and the ASC-ECU connector.

<Less than 1 kΩ> Check the ASC-ECU connector, and repair if necessary. If the ASC-ECU connector is in good condition, replace the ASC-ECU.

STEP 17. Connector check: joint connector (CAN3)

caution

The strand end of the twist wire should be within 10 cm from the connector. For details refer to

When checking the joint connector, ensure that its wiring harness side and its short pins are not damaged.

Is the check result normal?

Go to Step 18

Repair a defective connector or replace the joint connector.

STEP 18. Resistance measurement at joint connector (CAN3).

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 (CAN3), and measure at the wiring harness side.

(2) Turn the ignition switch to the LOCK (OFF) position.

(3)

caution

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

Ensure that the negative battery terminal is disconnected.

(4) Resistance between joint connector (CAN3) terminal Nos.11 and 22

OK: 120 ± 20 ohms

Is the check result normal?

<Within 120 ± 20 ohms> Go to Step 20

: <Not within 120 ± 20 ohms> Go to Step 19

STEP 19. Resistance measurement at ETACS-ECU connector.

caution

A digital multimeter should be used. For details refer to

(1) Remove the ETACS-ECU, and measure at the equipment side.

(2) Resistance at ETACS-ECU connector terminal Nos.18 and 19

OK: 120 ± 20 ohms

caution

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

Is the check result normal?

<Within 120 ± 20 ohms> Repair the wiring harness between joint connector (CAN3) and the ETACS-ECU connector.

<Not within 120 ± 20 ohms> Check the ETACS-ECU connector, and repair if necessary. If the ETACS-ECU connector is in good condition, replace the ETACS-ECU.

STEP 20. Resistance measurement at joint connector (CAN3).

note	Step 20 and 21 are only for AWD. On vehicles without it, go to Step 22.

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 (CAN3), and measure at the wiring harness side.

(2) Turn the ignition switch to the LOCK (OFF) position.

(3)

caution

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

Ensure that the negative battery terminal is disconnected.

(4) Resistance between joint connector (CAN3) terminal Nos.5 and 16

OK: 1 kΩ or more

Is the check result normal?

<1 kΩ or more> Go to Step 22

<Less than 1 kΩ> Go to Step 21

STEP 21. Resistance measurement at AWD-ECU <Vehicles without S-AWC> or AWC-ECU <Vehicles with S-AWC> connector.

caution

A digital multimeter should be used. For details refer to

(1) Remove the AWD-ECU <Vehicles without S-AWC> or AWC-ECU <Vehicles with S-AWC>, and measure at the equipment side.

(2) Resistance at AWD-ECU connector terminal Nos.5 and 13 <Vehicles without S-AWC>

OK: 1 kΩ or more

(3) Resistance at AWC-ECU connector terminal Nos.23 and 24 <Vehicles with S-AWC>

OK: 1 kΩ or more

caution

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

Is the check result normal?

<1 kΩ or more> Check intermediate connector, and repair if necessary. If the intermediate connector is in good condition, repair the wiring harness between joint connector (CAN3) and the AWD-ECU <Vehicles without S-AWC> or AWC-ECU <Vehicles with S-AWC> connector.

<Less than 1 kΩ> Check the AWD-ECU <Vehicles without S-AWC> or AWC-ECU <Vehicles with S-AWC> connector, and repair if necessary. If the AWD-ECU <Vehicles without S-AWC> or AWC-ECU <Vehicles with S-AWC> connector is in good condition, replace the AWD-ECU <Vehicles without S-AWC> or AWC-ECU <Vehicles with S-AWC>.

STEP 22. Resistance measurement at joint connector (CAN3).

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 (CAN3), and measure at the wiring harness side.

(2) Turn the ignition switch to the LOCK (OFF) position.

(3)

caution

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

Ensure that the negative battery terminal is disconnected.

(4) Resistance between joint connector (CAN3) terminal Nos.6 and 17

OK: 1 kΩ or more

Is the check result normal?

<1 kΩ or more> Go to Step 24

<Less than 1 kΩ> Go to Step 23

STEP 23. Resistance measurement at column switch connector.

caution

A digital multimeter should be used. For details refer to

(1) Remove the column switch assembly, and measure at the equipment side.

(2) Resistance at column switch connector terminal Nos.3 and 4

OK: 1 kΩ or more

caution

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

Is the check result normal?

<1 kΩ or more> Repair the wiring harness between joint connector (CAN3) and the column switch connector.

<Less than 1 kΩ> Check the column switch connector, and repair if necessary. If the column switch connector is in good condition, replace the column switch assembly (steering wheel sensor).

STEP 24. Resistance measurement at joint connector (CAN3).

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 (CAN3), and measure at the wiring harness side.

(2) Turn the ignition switch to the LOCK (OFF) position.

(3)

caution

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

Ensure that the negative battery terminal is disconnected.

(4) Resistance between joint connector (CAN3) terminal Nos.4 and 15

OK: 1 kΩ or more

caution

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

Is the check result normal?

<1 kΩ or more> Go to Step 26

<Less than 1 kΩ> Go to Step 25

STEP 25. Resistance measurement at occupant classification-ECU connector.

caution

A digital multimeter should be used. For details refer to

(1) Remove the occupant classification-ECU, and measure at the equipment side.

(2) Resistance at occupant classification-ECU connector terminal Nos.1 and 3

OK: 1 kΩ or more

Is the check result normal?

<Less than 1 kΩ> Check the occupant classification-ECU connector, and repair if necessary. If the occupant classification-ECU connector is in good condition, replace the occupant classification-ECU.

STEP 26. Resistance measurement at joint connector (CAN3).

note	Step 26 and 27 are only for vehicles with FCM. On vehicles without it, go to Step 28.

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 (CAN3), and measure at the wiring harness side.

(2) Turn the ignition switch to the LOCK (OFF) position.

(3)

caution

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

Ensure that the negative battery terminal is disconnected.

(4) Resistance between joint connector (CAN3) terminal Nos.7 and 18

OK: 1 kΩ or more

Is the check result normal?

<1 kΩ or more> Go to Step 28

<Less than 1 kΩ> Go to Step 27

STEP 27. Resistance measurement at FCM/LDW/AHB-ECU connector.

caution

A digital multimeter should be used. For details refer to

(1) Remove the FCM/LDW/AHB-ECU, and measure at the equipment side.

(2) Resistance at FCM/LDW/AHB-ECU connector terminal Nos.2 and 8

OK: 1 kΩ or more

caution

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

Is the check result normal?

<Less than 1 kΩ> Check the FCM/LDW/AHB-ECU connector, and repair if necessary. If the FCM/LDW/AHB-ECU connector is in good condition, replace the FCM/LDW/AHB-ECU.

STEP 28. Resistance measurement at joint connector (CAN3).

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 (CAN3), and measure at the wiring harness side.

(2) Turn the ignition switch to the LOCK (OFF) position.

(3)

caution

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

Ensure that the negative battery terminal is disconnected.

(4) Resistance between joint connector (CAN3) terminal Nos.8 and 19

OK: 1 kΩ or more

Is the check result normal?

<1 kΩ or more> Go to Step 30

<Less than 1 kΩ> Go to Step 29

STEP 29. Resistance measurement at SRS-ECU connector.

caution

A digital multimeter should be used. For details refer to

(1) Remove the SRS-ECU, and measure at the equipment side.

(2) Resistance at SRS-ECU connector terminal Nos.30 and 29

OK: 1 kΩ or more

caution

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

Is the check result normal?

<1 kΩ or more> Repair the wiring harness between joint connector (CAN3) and the SRS-ECU connector.

<Less than 1 kΩ> Check the SRS-ECU connector, and repair if necessary. If the SRS-ECU connector is in good condition, replace the SRS-ECU.

STEP 30. Resistance measurement at joint connector (CAN3).

note	Step 30 and 31 are only for vehicles with electric parking brake system. On vehicles without it, go to Step 32.

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 (CAN3), and measure at the wiring harness side.

(2) Turn the ignition switch to the LOCK (OFF) position.

(3)

caution

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

Ensure that the negative battery terminal is disconnected.

(4) Resistance between joint connector (CAN3) terminal Nos.1 and 12

OK: 1 kΩ or more

Is the check result normal?

<1 kΩ or more> Go to Step 32

<Less than 1 kΩ> Go to Step 31

STEP 31. Resistance measurement at electric parking brake ECU connector.

caution

A digital multimeter should be used. For details refer to

(1) Remove the electric parking brake ECU, and measure at the equipment side.

(2) Resistance at electric parking brake ECU connector terminal Nos.40 and 30

OK: 1 kΩ or more

caution

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

Is the check result normal?

<Less than 1 kΩ> Check the electric parking brake ECU connector, and repair if necessary. If the electric parking brake ECU connector is in good condition, replace the electric parking brake ECU.

STEP 32. Resistance measurement at joint connector (CAN3).

note	Step 32 and 33 are only for vehicles with Blind Spot Warning [BSW] (with Lane Change Assist) system. On vehicles without it, go to Step 34.

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 (CAN3), and measure at the wiring harness side.

(2) Turn the ignition switch to the LOCK (OFF) position.

(3)

caution

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

Ensure that the negative battery terminal is disconnected.

(4) Resistance between joint connector (CAN3) terminal Nos.2 and 13

OK: 1 kΩ or more

Is the check result normal?

<1 kΩ or more> Go to Step 34

<Less than 1 kΩ> Go to Step 33

STEP 33. Resistance measurement at gateway-ECU connector.

caution

A digital multimeter should be used. For details refer to

(1) Remove the gateway-ECU, and measure at the equipment side.

(2) Resistance at gateway-ECU connector terminal Nos.3 and 2

OK: 1 kΩ or more

caution

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

Is the check result normal?

<1 kΩ or more> Repair the wiring harness between joint connector (CAN3) and the gateway-ECU.

<Less than 1 kΩ> Check the gateway-ECU connector, and repair if necessary. If the gateway-ECU connector is in good condition, replace the gateway-ECU.

STEP 34. Resistance measurement at joint connector (CAN3).

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 the joint connector (CAN3), and measure at the wiring harness side.

(2) Turn the ignition switch to the LOCK (OFF) position.

(3)

caution

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

Ensure that the negative battery terminal is disconnected.

(4) Resistance between joint connector (CAN3) terminal Nos.9 and 20

OK: 1 kΩ or more

caution

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

Is the check result normal?

<1 kΩ or more> Repair the wiring harness between joint connector (CAN3) and the C-126 intermediate connector.

<Less than 1 kΩ> Check the data link connector, and repair if necessary. If the data link connector is in good condition, repair the wiring harness between joint connector (CAN3) and the data link connector.