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Diagnostic Item 5: Diagnose shorts between CAN_H and L lines [CAN-C (Main)].
 
 
cautionWhen 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.
 
 
TROUBLE JUDGMENT
When all of the following conditions are met, the scan tool (M.U.T.-IIISE) determines that a short circuit is present between CAN_L and CAN_H lines.
  • The scan tool (M.U.T.-IIISE) cannot receive the periodic transmission data from any ECUs.
  • The voltage between CAN-C (CAN_L and CAN_H lines) is 1.0 volt or more, 4.0 volts 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 column switch (steering wheel sensor)
  • Malfunction of the SRS-ECU
  • Malfunction of the occupant classification-ECU
  • Malfunction of the gateway-ECU
  • Malfunction of the electric parking brake ECU <Vehicles with electric parking brake>
  • Malfunction of the FCM/LDW/AHB-ECU
  • Malfunction of the AWC-ECU <AWD>
  • Malfunction of the TCM
  • Malfunction of the ASC-ECU
  • Malfunction of the EPS-ECU
  • Malfunction of the ACC/FCM-ECU <Vehicles with ACC>
  • Malfunction of the ECM
 
 
DIAGNOSIS
Required Special Tools:
  • MB991223: Harness Set
  • MB992006: Extra Fine Probe
STEP 1. Connector check: C-149 intermediate connector
cautionThe strand end of the twist wire should be within 10 cm (3.9 inches) 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-149 intermediate connector.
cautionA digital multimeter should be used. For details refer to .
cautionThe 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)
cautionWhen measuring the resistance, disconnect the negative battery terminal. For details refer to .
Ensure that the negative battery terminal is disconnected.
(4) Resistance between C-149 intermediate connector terminal Nos.19 and 18
OK: 120 ± 20 ohms
Is the check result normal?
<Within 120 ± 20 ohms> Go to Step 16.
<Not within 120 ± 20 ohms> Go to Step 3.
 
STEP 3. Connector check: joint connector (CAN3)
cautionThe strand end of the twist wire should be within 10 cm (3.9 inches) 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 (CAN4)
cautionThe strand end of the twist wire should be within 10 cm (3.9 inches) 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 (CAN3).
cautionA digital multimeter should be used. For details refer to .
cautionThe 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)
cautionWhen 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.10 and 21
OK: 120 ± 20 ohms
Is the check result normal?
<Within 120 ± 20 ohms> Go to Step 10.
: <Not within 120 ± 20 ohms> Go to Step 6.
: <Not within 120 ± 20 ohms> Go to Step 8.
 
STEP 6. Resistance measurement at joint connector (CAN4).
cautionA digital multimeter should be used. For details refer to .
cautionThe 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)
cautionWhen 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 (CAN4) terminal Nos.9 and 20
OK: 1 kΩ or more
Is the check result normal?
<1 kΩ or more> Go to Step 8.
<Less than 1 kΩ> Go to Step 7.
 
STEP 7. Resistance measurement at ACC/FCM-ECU connector.
cautionA digital multimeter should be used. For details refer to .
cautionStrictly observe the specified wiring harness repair procedure. 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.6 and 1
OK: 1 kΩ or more
Is the check result normal?
<1 kΩ or more> Repair the wiring harness between joint connector (CAN4) 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 8. Resistance measurement at joint connector (CAN4).
cautionA digital multimeter should be used. For details refer to .
cautionThe test wiring harness should be used. For details refer to .
cautionStrictly observe the specified wiring harness repair procedure. 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)
cautionWhen 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 (CAN4) terminal Nos.10 and 21
OK: 120 ± 20 ohms
Is the check result normal?
<Within 120 ± 20 ohms> Repair the wiring harness between joint connector (CAN4) and the joint connector (CAN3).
<Not within 120 ± 20 ohms> Go to Step 9.
 
STEP 9. Resistance measurement at ECM connector.
cautionA digital multimeter should be used. For details refer to .
cautionStrictly observe the specified wiring harness repair procedure. For details refer to .
(1) Remove the ECM, and measure at the equipment side.
(2) Resistance between ECM connector terminal Nos.151 and 152
OK: 120 ± 20 ohms
Is the check result normal?
<Within 120 ± 20 ohms> Repair the wiring harness between joint connector (CAN4) 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 10. Resistance measurement at joint connector (CAN3).
cautionA digital multimeter should be used. For details refer to .
cautionThe 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)
cautionWhen 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 12.
<Less than 1 kΩ> Go to Step 11.
 
STEP 11. Resistance measurement at TCM connector.
cautionA digital multimeter should be used. For details refer to .
cautionStrictly observe the specified wiring harness repair procedure. For details refer to .
(1) Remove the TCM, and measure at the equipment side.
(2) Resistance between TCM connector terminal Nos.9 and 10
OK: 1 kΩ or more
Is the check result normal?
<1 kΩ or more> Repair the wiring harness between joint connector (CAN3) 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 12. Resistance measurement at joint connector (CAN3).
cautionA digital multimeter should be used. For details refer to .
cautionThe 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)
cautionWhen 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 14.
<Less than 1 kΩ> Go to Step 13.
 
STEP 13. Resistance measurement at ASC-ECU connector.
cautionA digital multimeter should be used. For details refer to .
cautionStrictly observe the specified wiring harness repair procedure. 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
Is the check result normal?
<1 kΩ or more> Repair the wiring harness between joint connector (CAN3) 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 14. Resistance measurement at joint connector (CAN3).
cautionA digital multimeter should be used. For details refer to .
cautionThe test wiring harness should be used. For details refer to .
cautionStrictly observe the specified wiring harness repair procedure. 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)
cautionWhen 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
Is the check result normal?
<1 kΩ or more> Repair the wiring harness between joint connector (CAN3) and C-149 intermediate connector.
<Less than 1 kΩ> Go to Step 15.
 
STEP 15. Resistance measurement at EPS-ECU connector.
cautionA digital multimeter should be used. For details refer to .
cautionStrictly observe the specified wiring harness repair procedure. For details refer to .
(1) Remove the EPS-ECU, and measure at the equipment side.
(2) Resistance between EPS-ECU connector terminal Nos.26 and 25
OK: 1 kΩ or more
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 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 16. Connector check: joint connector (CAN1)
cautionThe 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 17.
Repair a defective connector or replace the joint connector.
 
STEP 17. Resistance measurement at joint connector (CAN1).
cautionA digital multimeter should be used. For details refer to .
cautionThe test wiring harness should be used. For details refer to .
(1) Disconnect joint connector (CAN1), and measure at the wiring harness side.
(2) Turn the ignition switch to the "LOCK" (OFF) position.
(3)
cautionWhen 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: 120 ± 20 ohms
Is the check result normal?
<Within 120 ± 20 ohms> Go to Step 19.
<Not within 120 ± 20 ohms> Go to Step 18.
 
STEP 18. Resistance measurement at ETACS-ECU connector.
cautionA digital multimeter should be used. For details refer to .
cautionStrictly observe the specified wiring harness repair procedure. For details refer to .
(1) Remove the ETACS-ECU, and measure at the equipment side.
(2) Resistance at ETACS-ECU connector terminal Nos.19 and 18
OK: 120 ± 20 ohms
Is the check result normal?
<Within 120 ± 20 ohms> Repair the wiring harness between joint connector (CAN1) 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 19. Resistance measurement at joint connector (CAN1).
cautionA digital multimeter should be used. For details refer to .
cautionThe test wiring harness should be used. For details refer to .
(1) Disconnect joint connector (CAN1), and measure at the wiring harness side.
(2) Turn the ignition switch to the "LOCK" (OFF) position.
(3)
cautionWhen 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.11 and 22
OK: 1 kΩ or more
Is the check result normal?
: <1 kΩ or more> Go to Step 23.
: <Less than 1 kΩ> Go to Step 20.
: <Less than 1 kΩ> Go to Step 22.
 
STEP 20. Resistance measurement at joint connector (CAN2).
cautionA digital multimeter should be used. For details refer to .
cautionThe test wiring harness should be used. For details refer to .
(1) Disconnect joint connector (CAN2), and measure at the wiring harness side.
(2) Turn the ignition switch to the "LOCK" (OFF) position.
(3)
cautionWhen 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 22.
<Less than 1 kΩ> Go to Step 21.
 
STEP 21. Resistance measurement at AWC-ECU connector.
cautionA digital multimeter should be used. For details refer to .
(1) Remove the AWC-ECU, and measure at the equipment side.
(2) Resistance at AWC-ECU connector terminal Nos.5 and 13
OK: 1 kΩ or more
cautionStrictly 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 connector is in good condition, repair the wiring harness between joint connector (CAN2) and the AWC-ECU connector.
<Less than 1 kΩ> Check the AWC-ECU connector, and repair if necessary. If the AWC-ECU connector is in good condition, replace the AWC-ECU.
 
STEP 22. Resistance measurement at FCM/LDW/AHB-ECU connector.
cautionA digital multimeter should be used. For details refer to .
cautionStrictly observe the specified wiring harness repair procedure. 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
Is the check result normal?
<1 kΩ or more> Check intermediate connector or joint connector (CAN2), and repair if necessary. If the connector is in good condition, repair the wiring harness between joint connector (CAN1) and the FCM/LDW/AHB-ECU connector.
<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 23. Resistance measurement at joint connector (CAN1).
cautionA digital multimeter should be used. For details refer to .
cautionThe test wiring harness should be used. For details refer to .
(1) Disconnect joint connector (CAN1), and measure at the wiring harness side.
(2) Turn the ignition switch to the "LOCK" (OFF) position.
(3)
cautionWhen 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
Is the check result normal?
<1 kΩ or more> Go to Step 25.
<Less than 1 kΩ> Go to Step 24.
 
STEP 24. Resistance measurement at column switch connector.
cautionA digital multimeter should be used. For details refer to .
cautionStrictly observe the specified wiring harness repair procedure. For details refer to .
(1) Remove the column switch, and measure at the equipment side.
(2) Resistance at column switch connector terminal Nos.13 and 14
OK: 1 kΩ or more
Is the check result normal?
<1 kΩ or more> Repair the wiring harness between joint connector (CAN1) 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.
 
STEP 25. Resistance measurement at joint connector (CAN1).
cautionA digital multimeter should be used. For details refer to .
cautionThe test wiring harness should be used. For details refer to .
(1) Disconnect joint connector (CAN1), and measure at the wiring harness side.
(2) Turn the ignition switch to the "LOCK" (OFF) position.
(3)
cautionWhen 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
Is the check result normal?
<1 kΩ or more> Go to Step 27.
<Less than 1 kΩ> Go to Step 26.
 
STEP 26. Resistance measurement at occupant classification-ECU connector
cautionA digital multimeter should be used. For details refer to .
cautionStrictly observe the specified wiring harness repair procedure. 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. 12 and 14
OK: 1 kΩ or more
Is the check result normal?
<1 kΩ or more> Check the front seat assembly (passenger's side) connector, and repair if necessary. If the front seat assembly (passenger's side) connector is in good condition, repair the wiring harness between joint connector (CAN1) and the occupant classification-ECU connector.
<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 27. Resistance measurement at joint connector (CAN1).
cautionA digital multimeter should be used. For details refer to .
cautionThe test wiring harness should be used. For details refer to .
(1) Disconnect joint connector (CAN1), and measure at the wiring harness side.
(2) Turn the ignition switch to the "LOCK" (OFF) position.
(3)
cautionWhen 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
Is the check result normal?
: <1 kΩ or more> Go to Step 29.
: <1 kΩ or more> Go to Step 31.
<Less than 1 kΩ> Go to Step 28.
 
STEP 28. Resistance measurement at SRS-ECU connector
cautionA digital multimeter should be used. For details refer to .
cautionStrictly observe the specified wiring harness repair procedure. For details refer to .
(1) Remove the SRS-ECU, and measure at the equipment side.
(2) Resistance at SRS-ECU connector terminal Nos.25 and 24
OK: 1 kΩ or more
Is the check result normal?
<1 kΩ or more> Repair the wiring harness between joint connector (CAN1) and the SRS-ECU.
<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 29. Resistance measurement at joint connector (CAN1)
cautionA digital multimeter should be used. For details refer to .
cautionThe test wiring harness should be used. For details refer to .
cautionStrictly observe the specified wiring harness repair procedure. 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)
cautionWhen 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 15
OK: 1 kΩ or more
Is the check result normal?
<1 kΩ or more> Go to Step 31.
<Less than 1 kΩ> Go to Step 30.
 
STEP 30. Resistance measurement at electric parking brake ECU connector
cautionA digital multimeter should be used. For details refer to .
cautionStrictly observe the specified wiring harness repair procedure. For details refer to .
(1) Remove the electric parking brake ECU, and measure at the equipment side.
(2) Resistance between electric parking brake ECU connector terminal Nos.40 and 30
OK: 1 kΩ or more
Is the check result normal?
<1 kΩ or more> Repair the wiring harness between joint connector (CAN1) and the electric parking brake ECU.
<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 31. Resistance measurement at joint connector (CAN1)
cautionA digital multimeter should be used. For details refer to .
cautionThe test wiring harness should be used. For details refer to .
cautionStrictly observe the specified wiring harness repair procedure. For details refer to .
(1) Disconnect joint connector (CAN1), and measure at the wiring harness side.
(2) Turn the ignition switch to the "LOCK" (OFF) position.
(3)
cautionWhen 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. 2 and 13
OK: 1 kΩ or more
Is the check result normal?
<1 kΩ or more> Repair the wiring harness between joint connector (CAN1) and the C-149 intermediate connector.
<Less than 1 kΩ> Go to Step 32.
 
STEP 32. Resistance measurement at gateway-ECU connector
cautionA digital multimeter should be used. For details refer to .
cautionStrictly observe the specified wiring harness repair procedure. 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
Is the check result normal?
<1 kΩ or more> Repair the wiring harness between joint connector (CAN1) 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.