Diagnosis Item 4: Diagnose shorts between CAN_H and L lines (CAN-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.
  • 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 JUDGEMENT


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

TROUBLESHOOTING HINTS



DIAGNOSIS PROCEDURE

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 .

Q. 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 Ω

Q. Is the check result normal?
<Within 120 ± 20 Ω> Go to Step 17.
<Not within 120 ± 20 Ω> 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.

Q. Is the check result normal?

YES <vehicles without ACC> : Go to Step 5.

YES <vehicles with ACC> : Go to Step 4.

Repair a defective connector or replace the joint connector.

STEP 4. Connector check: joint connector (CAN2)
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.

Q. 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.10 and 21
OK: 120 ± 20 Ω
caution Strictly observe the specified wiring harness repair procedure. For details refer to .

Q. Is the check result normal?
YES <vehicles without ACC> : <Within 120 ± 20 Ω> Go to Step 8.
YES <vehicles with ACC> : <Within 120 ± 20 Ω> Go to Step 7.
<Not within 120 ± 20 Ω> Go to Step 6.

STEP 6. Resistance measurement at engine-ECU connector.
caution A digital multimeter should be used. For details refer to .
(1)Remove the engine-ECU, and measure at the equipment side.
(2)Resistance between engine-ECU connector terminal Nos.90 and 91
OK: 120 ± 20 Ω
caution Strictly observe the specified wiring harness repair procedure. For details refer to .

Q. Is the check result normal?
<Within 120 ± 20 Ω> Repair the wiring harness between joint connector (CAN1) and the engine-ECU connector.
<Not within 120 ± 20 Ω> Check the engine-ECU connector, and repair if necessary. If the engine-ECU connector is in good condition, replace the engine-ECU.

STEP 7. 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.10 and 21
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> Go to Step 9.
<Less than 1 kΩ> Go to Step 8.

STEP 8. Resistance measurement at ACC/FCM-ECU connector.
caution A digital multimeter should be used. For details refer to .
(1)Remove the ACC/FCM-ECU, and measure at the equipment side.
(2)Resistance between ACC/FCM-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 .

Q. 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 (CAN1) and the ACC/FCM-ECU connector.
<Less than 1 kΩ> Check the ACC/FCM-ECU connector, and repair if necessary. If the ACC/FCM-ECU connector is in good condition, replace the ACC/FCM-ECU.

STEP 9. 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 17
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> Go to Step 11.
<Less than 1 kΩ> Go to Step 10.

STEP 10. Resistance measurement at CVT-ECU <CVT> connector or A/T-ECU <A/T> connector.
caution A digital multimeter should be used. For details refer to .
(1)Remove the CVT-ECU <CVT> or A/T-ECU <A/T>, and measure at the equipment side.
(2)Resistance between CVT-ECU connector terminal Nos.4 and 5 <CVT>
OK: 1 kΩ or more
(3)Resistance between A/T-ECU 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 .

Q. 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 (CAN1) and the CVT-ECU <CVT> connector or A/T-ECU <A/T> connector.
<Less than 1 kΩ> Check the CVT-ECU <CVT> connector or A/T-ECU <A/T> connector, and repair if necessary. If the CVT-ECU <CVT> connector or A/T-ECU <A/T> connector is in good condition, replace the CVT-ECU <CVT> or A/T-ECU <A/T>.

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.8 and 19
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 <vehicles without AS&G system> : <1 kΩ or more> Go to Step 15.
YES <vehicles with AS&G system> : <1 kΩ or more> Go to Step 13.
<Less than 1 kΩ> Go to Step 12.

STEP 12. 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.3 and 4
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 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 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.7 and 18
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> Go to Step 15.
<Less than 1 kΩ> Go to Step 14.

STEP 14. Resistance measurement at AS&G-ECU connector.
caution A digital multimeter should be used. For details refer to .
(1)Remove the AS&G-ECU, and measure at the equipment side.
(2)Resistance between AS&G-ECU connector terminal Nos.1 and 14
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 the wiring harness between joint connector (CAN1) and the AS&G-ECU connector.
<Less than 1 kΩ> Check the AS&G-ECU connector, and repair if necessary. If the AS&G-ECU connector is in good condition, replace the AS&G-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.9 and 20
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 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 ABS-ECU <vehicles without ASC> or ASC-ECU <vehicles with ASC> connector.
caution A digital multimeter should be used. For details refer to .
(1)Remove the ABS-ECU <vehicles without ASC> or ASC-ECU <vehicles with ASC>, and measure at the equipment side.
(2)Resistance between ABS-ECU <vehicles without ASC> or ASC-ECU <vehicles with ASC> connector terminal Nos.11 and 10
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 the wiring harness between joint connector (CAN1) and the ABS-ECU <vehicles without ASC> or ASC-ECU <vehicles with ASC> connector.
<Less than 1 kΩ> Check the ABS-ECU <vehicles without ASC> or ASC-ECU <vehicles with ASC> connector, and repair if necessary. If the ABS-ECU <vehicles without ASC> or ASC-ECU <vehicles with ASC> connector is in good condition, replace the ABS-ECU <vehicles without ASC> or ASC-ECU <vehicles with ASC>.

STEP 17. Connector check: joint connector (CAN3) <LHD> or joint connector (CAN4) <RHD>
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.

Q. 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 <LHD>
OK: 120 ± 20 Ω
(5)Resistance between joint connector (CAN3) terminal Nos.4 and 15 <RHD>
OK: 120 ± 20 Ω
caution Strictly observe the specified wiring harness repair procedure. For details refer to .

Q. Is the check result normal?
YES <2WD> : <Within 120 ± 20 Ω> Go to Step 22.
YES <4WD> : <Within 120 ± 20 Ω> Go to Step 20.
NO : <Not within 120 ± 20 Ω> 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 Ω

Q. Is the check result normal?
<Within 120 ± 20 Ω> Repair the wiring harness between joint connector (CAN3) and the ETACS-ECU connector.
<Not within 120 ± 20 Ω> 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).
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
caution Strictly observe the specified wiring harness repair procedure. For details refer to .

Q. 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 4WD-ECU connector.
caution A digital multimeter should be used. For details refer to .
(1)Remove the 4WD-ECU, and measure at the equipment side.
(2)Resistance at 4WD-ECU connector terminal Nos.5 and 13
OK: 1 kΩ or more

Q. 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 4WD-ECU connector.
<Less than 1 kΩ> Check the 4WD-ECU connector, and repair if necessary. If the 4WD-ECU connector is in good condition, replace the 4WD-ECU.

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 <LHD>
OK: 1 kΩ or more
(5)Resistance between joint connector (CAN3) terminal Nos.4 and 15 <RHD>
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 <vehicles without LDW> : <1 kΩ or more> Go to Step 26.
YES <vehicles without LDW> : <1 kΩ or more> Go to Step 24.
<Less than 1 kΩ> Go to Step 23.

STEP 23. Resistance measurement at steering wheel sensor connector.
caution A digital multimeter should be used. For details refer to .
(1)Remove the steering wheel sensor, and measure at the equipment side.
(2)Resistance at steering wheel sensor connector terminal Nos.3 and 4
OK: 1 kΩ or more

Q. Is the check result normal?
<1 kΩ or more> Repair the wiring harness between joint connector (CAN3) and the steering wheel sensor connector.
<Less than 1 kΩ> 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.

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.7 and 18
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> Go to Step 26.
<Less than 1 kΩ> Go to Step 25.

STEP 25. Resistance measurement at LDW-ECU connector.
caution A digital multimeter should be used. For details refer to .
(1)Remove the LDW-ECU, and measure at the equipment side.
(2)Resistance at LDW-ECU connector terminal Nos.2 and 3
OK: 1 kΩ or more

Q. Is the check result normal?
<1 kΩ or more> Repair the wiring harness between joint connector (CAN3) and the LDW-ECU connector.
<Less than 1 kΩ> Check the LDW-ECU connector, and repair if necessary. If the LDW-ECU connector is in good condition, replace the LDW-ECU.

STEP 26. 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 <LHD>
OK: 1 kΩ or more
(5)Resistance between joint connector (CAN3) terminal Nos.4 and 15 <RHD>
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> Go to Step 28.
<Less than 1 kΩ> Go to Step 27.

STEP 27. 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.29 and 30
OK: 1 kΩ or more

Q. 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 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 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 <LHD>
OK: 1 kΩ or more
(5)Resistance between joint connector (CAN3) terminal Nos.4 and 15 <RHD>
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 the wiring harness between joint connector (CAN3) and the C-126 intermediate connector.
<Less than 1 kΩ> Check the diagnosis connector, and repair if necessary. If the diagnosis connector is in good condition, repair the wiring harness between joint connector (CAN3) and the diagnosis connector.