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Diagnostic Item 24: Diagnose shorts between CAN_H and L lines (CAN-C-Mid).
 
 
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-Mid (CAN_L and CAN_H lines) is 1.0 volt or more, 4.0 volts or less.
  • The resistance at CAN-C-Mid (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 KOS&OSS-ECU <Vehicles with KOS>
  • Malfunction of the camera-ECU <Vehicles with multi around monitor>
  • Malfunction of the HUD <Vehicles with HUD>
  • Malfunction of the A/C controller assembly
  • Malfunction of the multivision display <Vehicles with smartphone link display audio>
  • Malfunction of the combination meter
  • Malfunction of the TCU <Vehicles with TCU>
 
 
DIAGNOSIS
Required Special Tools:
  • MB991223: Harness Set
  • MB992006: Extra Fine Probe
STEP 1. Connector check: joint connector (CAN5)
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 2
Repair a defective connector or replace the joint connector.
 
STEP 2. Resistance measurement at joint connector (CAN5).
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 (CAN5) terminal Nos.11 and 22
OK: 120 ± 20 ohms
Is the check result normal?
<Within 120 ± 20 ohms> Go to Step 4.
: <Not within 120 ± 20 ohms> Go to Step 3.
 
STEP 3. Resistance measurement at ETACS-ECU connector.
cautionA digital multimeter should be used. For details refer to .
(1) Remove the ETACS-ECU, and measure at the equipment side.
(2) Resistance between ETACS-ECU connector terminal Nos.17 and 16
OK: 120 ± 20 ohms
cautionStrictly 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 (CAN5) 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 4. Resistance measurement at joint connector (CAN5).
noteSteps 4 and 5 are only for vehicles with KOS. On vehicles without it, go to Step 6.
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 (CAN5) terminal Nos.6 and 17
OK: 1 kΩ or more
Is the check result normal?
<1 kΩ or more> Go to Step 6.
<Less than 1 kΩ> Go to Step 5.
 
STEP 5. Resistance measurement at KOS&OSS-ECU connector.
cautionA digital multimeter should be used. For details refer to .
(1) Remove the KOS&OSS-ECU, and measure at the equipment side.
(2) Resistance between KOS&OSS-ECU connector terminal Nos.35 and 51
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> Repair the wiring harness between joint connector (CAN5) and the KOS&OSS-ECU connector.
<Less than 1 kΩ> 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.
 
STEP 6. Resistance measurement at joint connector (CAN5).
noteSteps 6 and 7 are only for vehicles with multi around monitor. On vehicles without it, go to Step 8.
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 (CAN5) terminal Nos.4 and 15
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 camera-ECU connector.
cautionA digital multimeter should be used. For details refer to .
(1) Remove the camera-ECU, and measure at the equipment side.
(2) Resistance between camera-ECU connector terminal Nos.1 and 21
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 the intermediate connector, and repair if necessary. If the intermediate connector is in good condition, repair the wiring harness between joint connector (CAN5) and the camera-ECU connector.
<Less than 1 kΩ> Check the camera-ECU connector, and repair if necessary. If the camera-ECU connector is in good condition, replace the camera-ECU.
 
STEP 8. Resistance measurement at joint connector (CAN5).
noteSteps 8 and 9 are only for vehicles with HUD. On vehicles without it, go to Step 10.
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 (CAN5) terminal Nos.5 and 16
OK: 1 kΩ or more
Is the check result normal?
<1 kΩ or more> Go to Step 10.
<Less than 1 kΩ> Go to Step 9.
 
STEP 9. Resistance measurement at HUD connector.
cautionA digital multimeter should be used. For details refer to .
(1) Remove the HUD, and measure at the equipment side.
(2) Resistance between HUD connector terminal Nos.6 and 18
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> Repair the wiring harness between joint connector (CAN5) and the HUD connector.
<Less than 1 kΩ> Check the HUD connector, and repair if necessary. If the HUD connector is in good condition, replace the HUD.
 
STEP 10. Resistance measurement at joint connector (CAN5).
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 (CAN5), 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 (CAN5) terminal Nos.8 and 19
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 A/C controller assembly connector.
cautionA digital multimeter should be used. For details refer to .
(1) Remove the A/C controller assembly, and measure at the equipment side.
(2) Resistance at A/C controller assembly connector terminal Nos.32 and 31
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> Repair the wiring harness between joint connector (CAN5) and the A/C controller assembly connector.
<Less than 1 kΩ> Check the A/C controller assembly connector, and repair if necessary. If the A/C controller assembly connector is in good condition, replace the A/C controller assembly.
 
STEP 12. Resistance measurement at joint connector (CAN5).
noteSteps 12 and 13 are only for vehicles with smartphone link display audio. On vehicles without it, go to Step 14.
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 (CAN5), 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 (CAN5) terminal Nos.7 and 18
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> Go to Step 14.
<Less than 1 kΩ> Go to Step 13.
 
STEP 13. Resistance measurement at multivision display connector.
cautionA digital multimeter should be used. For details refer to .
(1) Remove the multivision display, and measure at the equipment side.
(2) Resistance at multivision display connector terminal Nos.3 and 13
OK: 1 kΩ or more
Is the check result normal?
<1 kΩ or more> Repair the wiring harness between joint connector (CAN5) and the multivision display connector.
<Less than 1 kΩ> Check the multivision display connector, and repair if necessary. If the multivision display connector is in good condition, replace the multivision display.
 
STEP 14. Resistance measurement at joint connector (CAN5).
noteSteps 14 and 15 are only for vehicles with TCU. On vehicles without it, go to Step 16 .
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 (CAN5), 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 (CAN5) terminal Nos.2 and 13
OK: 1 kΩ or more
Is the check result normal?
<1 kΩ or more> Go to Step 16.
<Less than 1 kΩ> Go to Step 15.
 
STEP 15. Resistance measurement at TCU connector.
cautionA digital multimeter should be used. For details refer to .
(1) Remove the TCU, and measure at the equipment side.
(2) Resistance at TCU connector terminal Nos.33 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> Repair the wiring harness between joint connector (CAN5) and the TCU connector.
<Less than 1 kΩ> Check the TCU connector, and repair if necessary. If the TCU connector is in good condition, replace the TCU.
 
STEP 16. Resistance measurement at joint connector (CAN5).
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 (CAN5), 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 (CAN5) terminal Nos.10 and 21
OK: 120 ± 20 ohms
Is the check result normal?
<Within 120 ± 20 ohms> The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction ).
<Not within 120 ± 20 ohms> Go to Step 17.
 
STEP 17. Resistance measurement at combination meter connector.
cautionA digital multimeter should be used. For details refer to .
(1) Remove the combination meter, and measure at the equipment side.
(2) Resistance at combination meter connector terminal Nos.14 and 15
OK: 120 ± 20 ohms
cautionStrictly 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 (CAN5) and the combination meter connector.
<Not within 120 ± 20 ohms> Check the combination meter connector, and repair if necessary. If the combination meter connector is in good condition, replace the combination meter.