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DIAGNOSTIC ITEM 21: Short to power supply or ground in both CAN_H and CAN_L lines of the CAN-B bus lines.
 
 
cautionWhen servicing a CAN bus line, ground yourself by touching a metal object such as an unpainted water pipe. If you fail to do so, a component connected to the CAN bus line may be damaged.

 
 
 
 
FUNCTION
If a short to power supply or ground is present in both CAN_H and CAN_L lines, this diagnosis result will be set.
 
 
TROUBLE JUDGMENT CONDITIONS
If a communication flag is set for the ETACS-ECU, no communication is present through the CAN-B line, and diagnostic trouble code U0019 is set, the ETACS-ECU determines that there is a failure.
 
 
TROUBLESHOOTING HINTS
  • Malfunction of the connector (ETACS-ECU connector improperly connected)
  • Malfunction of the wiring harness (CAN_H and CAN_L lines are short to power supply or ground on the CAN-B line.)
  • Malfunction of ECUs
 
 
DIAGNOSIS
Required Special Tools:
  • MB991223: Harness Set
  • MB992006: Extra Fine Probe
STEP 1. Check the wiring harness between ETACS-ECU connector C-411 and body ground for a short to power supply. Measure the voltage at ETACS-ECU connector C-411.
cautionA digital multimeter should be used. For details refer to .
cautionThe test wiring harness should be used. For details refer to .
(1) Disconnect ETACS-ECU connector C-411, and measure the voltage at the wiring harness side of ETACS-ECU connector.
(2) Turn the ignition switch to the ON position.
(3) Measure the voltage between ETACS-ECU connector terminal 6 and body ground.
OK: 4.7 volts or less
(4) Measure the voltage between ETACS-ECU connector terminal 7 and body ground.
OK: 4.7 volts or less
Do all the voltages measure 4.7 volts or less?
Go to Step 2.
Go to Step 10.
 
STEP 2. Check the wiring harness between joint connector (CAN1) C-05 and combination meter connector C-203 for a short to ground. Measure the resistance at joint connector (CAN1) C-05.
(1) Disconnect joint connector (CAN1), and measure the resistance at the wiring harness side of joint connector (CAN1).
(2) Measure the resistance between joint connector (CAN1) terminal 7 and body ground.
OK: 1 kΩ or more
(3) Measure the resistance between joint connector (CAN1) terminal 18 and body ground.
OK: 1 kΩ or more
Do all the resistances measure 1 kΩ or more?
(vehicles with KOS) : Go to Step 3.
(vehicles without KOS) : Go to Step 5.
Go to Step 18.
 
STEP 3. Check the wiring harness between joint connector (CAN1) C-05 and KOS-ECU connector C-10 for a short to ground. Measure the resistance at joint connector (CAN1) C-05.
(1) Disconnect joint connector (CAN1), and measure the resistance at the wiring harness side of joint connector (CAN1).
(2) Measure the resistance between joint connector (CAN1) terminal 9 and body ground.
OK: 1 kΩ or more
(3) Measure the resistance between joint connector (CAN1) terminal 20 and body ground.
OK: 1 kΩ or more
Do all the resistances measure 1 kΩ or more?
Go to Step 4.
Go to Step 19.
 
STEP 4. Check the wiring harness between joint connector (CAN1) C-05 and OSS-ECU connector C-14 for a short to ground. Measure the resistance at joint connector (CAN1) C-05.
(1) Disconnect joint connector (CAN1), and measure the resistance at the wiring harness side of joint connector (CAN1).
(2) Measure the resistance between joint connector (CAN1) terminal 5 and body ground.
OK: 1 kΩ or more
(3) Measure the resistance between joint connector (CAN1) terminal 16 and body ground.
OK: 1 kΩ or more
Do all the resistances measure 1 kΩ or more?
Go to Step 6.
Go to Step 20.
 
STEP 5. Check the wiring harness between joint connector (CAN1) C-05 and WCM connector C-09 for a short to ground. Measure the resistance at joint connector (CAN1) C-05.
(1) Disconnect joint connector (CAN1), and measure the resistance at the wiring harness side of joint connector (CAN1).
(2) Measure the resistance between joint connector (CAN1) terminal 9 and body ground.
OK: 1 kΩ or more
(3) Measure the resistance between joint connector (CAN1) terminal 20 and body ground.
OK: 1 kΩ or more
Do all the resistances measure 1 kΩ or more?
Go to Step 6.
Go to Step 21.
 
STEP 6. Check the wiring harness between joint connector (CAN1) C-05 and SRS-ECU connector C-126 for a short to ground. Measure the resistance at joint connector (CAN1) C-05.
(1) Disconnect joint connector (CAN1), and measure the resistance at the wiring harness side of joint connector (CAN1).
(2) Measure the resistance between joint connector (CAN1) terminal 10 and body ground.
OK: 1 kΩ or more
(3) Measure the resistance between joint connector (CAN1) terminal 21 and body ground.
OK: 1 kΩ or more
Do all the resistances measure 1 kΩ or more?
Go to Step 7.
Go to Step 22.
 
STEP 7. Check the wiring harness between joint connector (CAN1) C-05 and occupant classification-ECU connector D-48-2 for a short to ground. Measure the resistance at joint connector (CAN1) C-05.
(1) Disconnect joint connector (CAN1), and measure the resistance at the wiring harness side of joint connector (CAN1).
(2) Measure the resistance between joint connector (CAN1) terminal 4 and body ground.
OK: 1 kΩ or more
(3) Measure the resistance between joint connector (CAN1) terminal 15 and body ground.
OK: 1 kΩ or more
Do all the resistances measure 1 kΩ or more?
Go to Step 8.
Go to Step 23.
 
STEP 8. Check the wiring harness between joint connector (CAN1) C-05 and A/C control panel connector C-216 for a short to ground. Measure the resistance at joint connector (CAN1) C-05.
(1) Disconnect joint connector (CAN1), and measure the resistance at the wiring harness side of joint connector (CAN1).
(2) Measure the resistance between joint connector (CAN1) terminal 6 and body ground.
OK: 1 kΩ or more
(3) Measure the resistance between joint connector (CAN1) terminal 17 and body ground.
OK: 1 kΩ or more
Do all the resistances measure 1 kΩ or more?
Go to Step 9.
Go to Step 24.
 
STEP 9. Check the wiring harness between joint connector (CAN1) C-05 and ETACS-ECU connector C-411 for a short to ground. Measure the resistance at joint connector (CAN1) C-05.
(1) Disconnect joint connector (CAN1) and ETACS-ECU connector C-411, and measure the resistance at the wiring harness side of joint connector (CAN1).
(2) Measure the resistance between joint connector (CAN1) terminal 11 and body ground.
OK: 1 kΩ or more
(3) Measure the resistance between joint connector (CAN1) terminal 22 and body ground.
OK: 1 kΩ or more
Do all the resistances measure 1 kΩ or more?
Go to Step 25.
Repair the wiring harness between joint connector (CAN1) C-05 and ETACS-ECU connector C-411.
 
STEP 10. Check the wiring harness between joint connector (CAN1) C-05 and combination meter connector C-203 for a short to power supply. Measure the voltage at joint connector (CAN1) C-05.
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 the voltage at the wiring harness side of joint connector (CAN1).
(2) Turn the ignition switch to the ON position.
(3) Measure the voltage between joint connector (CAN1) terminal 7 and body ground.
OK: 4.7 volts or less
(4) Measure the voltage between joint connector (CAN1) terminal 18 and body ground.
OK: 4.7 volts or less
Do all the voltages measure 4.7 volts or less?
(vehicles with KOS) : Go to Step 11.
(vehicles without KOS) : Go to Step 13.
Go to Step 18.
 
STEP 11. Check the wiring harness between joint connector (CAN1) C-05 and KOS-ECU connector C-10 for a short to power supply. Measure the voltage at joint connector (CAN1) C-05.
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 the voltage at the wiring harness side of joint connector (CAN1).
(2) Turn the ignition switch to the ON position.
(3) Measure the voltage between joint connector (CAN1) terminal 9 and body ground.
OK: 4.7 volts or less
(4) Measure the voltage between joint connector (CAN1) terminal 20 and body ground.
OK: 4.7 volts or less
Do all the voltages measure 4.7 volts or less?
Go to Step 12.
Go to Step 19.
 
STEP 12. Check the wiring harness between joint connector (CAN1) C-05 and OSS-ECU connector C-14 for a short to power supply. Measure the voltage at joint connector (CAN1) C-05.
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 the voltage at the wiring harness side of joint connector (CAN1).
(2) Turn the ignition switch to the ON position.
(3) Measure the voltage between joint connector (CAN1) terminal 5 and body ground.
OK: 4.7 volts or less
(4) Measure the voltage between joint connector (CAN1) terminal 16 and body ground.
OK: 4.7 volts or less
Do all the voltages measure 4.7 volts or less?
Go to Step 14.
Go to Step 20.
 
STEP 13. Check the wiring harness between joint connector (CAN1) C-05 and WCM connector C-09 for a short to power supply. Measure the voltage at joint connector (CAN1) C-05.
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 the voltage at the wiring harness side of joint connector (CAN1).
(2) Turn the ignition switch to the ON position.
(3) Measure the voltage between joint connector (CAN1) terminal 9 and body ground.
OK: 4.7 volts or less
(4) Measure the voltage between joint connector (CAN1) terminal 20 and body ground.
OK: 4.7 volts or less
Do all the voltages measure 4.7 volts or less?
Go to Step 14.
Go to Step 21.
 
STEP 14. Check the wiring harness between joint connector (CAN1) C-05 and SRS-ECU connector C-126 for a short to power supply. Measure the voltage at joint connector (CAN1) C-05.
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 the voltage at the wiring harness side of joint connector (CAN1).
(2) Turn the ignition switch to the ON position.
(3) Measure the voltage between joint connector (CAN1) terminal 10 and body ground.
OK: 4.7 volts or less
(4) Measure the voltage between joint connector (CAN1) terminal 21 and body ground.
OK: 4.7 volts or less
Do all the voltages measure 4.7 volts or less?
Go to Step 15.
Go to Step 22.
 
STEP 15. Check the wiring harness between joint connector (CAN1) C-05 and occupant classification-ECU connector D-48-2 for a short to power supply. Measure the voltage at joint connector (CAN1) C-05.
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 the voltage at the wiring harness side of joint connector (CAN1).
(2) Turn the ignition switch to the ON position.
(3) Measure the voltage between joint connector (CAN1) terminal 4 and body ground.
OK: 4.7 volts or less
(4) Measure the voltage between joint connector (CAN1) terminal 15 and body ground.
OK: 4.7 volts or less
Do all the voltages measure 4.7 volts or less?
Go to Step 16.
Go to Step 23.
 
STEP 16. Check the wiring harness between joint connector (CAN1) C-05 and A/C control panel connector C-216 for a short to power supply. Measure the voltage at joint connector (CAN1) C-05.
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 the voltage at the wiring harness side of joint connector (CAN1).
(2) Turn the ignition switch to the ON position.
(3) Measure the voltage between joint connector (CAN1) terminal 6 and body ground.
OK: 4.7 volts or less
(4) Measure the voltage between joint connector (CAN1) terminal 17 and body ground.
OK: 4.7 volts or less
Do all the voltages measure 4.7 volts or less?
Go to Step 17.
Go to Step 24.
 
STEP 17. Check the wiring harness between joint connector (CAN1) C-05 and ETACS-ECU connector C-411 for a short to power supply. Measure the voltage at joint connector (CAN1) C-05.
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 ETACS-ECU connector C-411, and measure the voltage at the wiring harness side of joint connector (CAN1).
(2) Turn the ignition switch to the ON position.
(3) Measure the voltage between joint connector (CAN1) terminal 11 and body ground.
OK: 1.0 volts or less
(4) Measure the voltage between joint connector (CAN1) terminal 22 and body ground.
OK: 1.0 volts or less
Do all the voltages measure 1.0 volts or less?
Go to Step 25.
Repair the wiring harness between joint connector (CAN1) C-05 and ETACS-ECU connector C-411.
 
STEP 18. Using scan tool MB991958, diagnose the CAN bus line. (checking the combination meter for internal failure)
cautionStrictly observe the specified wiring harness repair procedure. For details refer to .
cautionTo prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
(1) Disconnect combination meter connector C-203.
(2) Connect scan tool MB991958 to the data link connector. Refer to "How to connect the Scan Tool (M.U.T.-III) ."
(3) Turn the ignition switch to the "ON" position.
(4) Diagnose CAN bus lines, and check if the scan tool MB991958 screen is as shown in the figure.
OK: The display of the scan tool MB991958 is as shown in the figure.
Does scan tool MB991958 screen correspond to the illustration?
Repair the wiring harness between joint connector (CAN1) C-05 and combination meter connector C-203.
Check combination meter connector C-203, and repair if necessary. If the combination meter connector is in good condition, replace the combination meter.
 
STEP 19. Using scan tool MB991958, diagnose the CAN bus line. (checking the KOS-ECU for internal failure)
cautionStrictly observe the specified wiring harness repair procedure. For details refer to .
cautionTo prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
(1) Disconnect KOS-ECU connector C-10.
(2) Connect scan tool MB991958 to the data link connector. Refer to "How to connect the Scan Tool (M.U.T.-III) ."
(3) Turn the ignition switch to the "ON" position.
(4) Diagnose CAN bus lines, and check if the scan tool MB991958 screen is as shown in the figure.
OK: The display of the scan tool MB991958 is as shown in the figure.
Does scan tool MB991958 screen correspond to the illustration?
Repair the wiring harness between joint connector (CAN1) C-05 and KOS-ECU connector C-10.
Check KOS-ECU connector C-10, and repair if necessary. If the KOS-ECU connector is in good condition, replace the KOS-ECU.
 
STEP 20. Using scan tool MB991958, diagnose the CAN bus line. (checking the OSS-ECU for internal failure)
cautionStrictly observe the specified wiring harness repair procedure. For details refer to .
cautionTo prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
(1) Disconnect OSS-ECU connector C-14.
(2) Connect scan tool MB991958 to the data link connector. Refer to "How to connect the Scan Tool (M.U.T.-III) ."
(3) Turn the ignition switch to the "ON" position.
(4) Diagnose CAN bus lines, and check if the scan tool MB991958 screen is as shown in the figure.
OK: The display of the scan tool MB991958 is as shown in the figure.
Does scan tool MB991958 screen correspond to the illustration?
Repair the wiring harness between joint connector (CAN1) C-05 and OSS-ECU connector C-14.
Check OSS-ECU connector C-14, and repair if necessary. If the OSS-ECU connector is in good condition, replace the OSS-ECU.
 
STEP 21. Using scan tool MB991958, diagnose the CAN bus line. (checking the WCM for internal failure)
cautionStrictly observe the specified wiring harness repair procedure. For details refer to .
cautionTo prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
(1) Disconnect WCM connector C-09.
(2) Connect scan tool MB991958 to the data link connector. Refer to "How to connect the Scan Tool (M.U.T.-III) ."
(3) Turn the ignition switch to the "ON" position.
(4) Diagnose CAN bus lines, and check if the scan tool MB991958 screen is as shown in the figure.
OK: The display of the scan tool MB991958 is as shown in the figure.
Does scan tool MB991958 screen correspond to the illustration?
Repair the wiring harness between joint connector (CAN1) C-05 and WCM connector C-09.
Check WCM connector C-09, and repair if necessary. If the WCM connector is in good condition, replace the WCM.
 
STEP 22. Using scan tool MB991958, diagnose the CAN bus line. (checking the SRS-ECU for internal failure)
cautionStrictly observe the specified wiring harness repair procedure. For details refer to .
cautionTo prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
(1) Disconnect SRS-ECU connector C-126.
(2) Connect scan tool MB991958 to the data link connector. Refer to "How to connect the Scan Tool (M.U.T.-III) ."
(3) Turn the ignition switch to the "ON" position.
(4) Diagnose CAN bus lines, and check if the scan tool MB991958 screen is as shown in the figure.
OK: The display of the scan tool MB991958 is as shown in the figure.
Does scan tool MB991958 screen correspond to the illustration?
Repair the wiring harness between joint connector (CAN1) C-05 and SRS-ECU connector C-126.
Check SRS-ECU connector C-126, and repair if necessary. If the SRS-ECU connector is in good condition, replace the SRS-ECU.
 
STEP 23. Using scan tool MB991958, diagnose the CAN bus line. (checking the occupant classification-ECU for internal failure)
cautionStrictly observe the specified wiring harness repair procedure. For details refer to .
cautionTo prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
(1) Disconnect occupant classification-ECU connector D-48-2.
(2) Connect scan tool MB991958 to the data link connector. Refer to "How to connect the Scan Tool (M.U.T.-III) ."
(3) Turn the ignition switch to the "ON" position.
(4) Diagnose CAN bus lines, and check if the scan tool MB991958 screen is as shown in the figure.
OK: The display of the scan tool MB991958 is as shown in the figure.
Does scan tool MB991958 screen correspond to the illustration?
Check intermediate connector C-17, and repair if necessary. If the intermediate connector is in good condition, repair the wiring harness between joint connector (CAN1) C-05 and occupant classification-ECU connector D-48-2.
Check occupant classification-ECU connector D-48-2, and repair if necessary. If the occupant classification-ECU connector is in good condition, replace the occupant classification-ECU.
 
STEP 24. Using scan tool MB991958, diagnose the CAN bus line. (checking the A/C control panel for internal failure)
cautionStrictly observe the specified wiring harness repair procedure. For details refer to .
cautionTo prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
(1) Disconnect A/C control panel connector C-216.
(2) Connect scan tool MB991958 to the data link connector. Refer to "How to connect the Scan Tool (M.U.T.-III) ."
(3) Turn the ignition switch to the "ON" position.
(4) Diagnose CAN bus lines, and check if the scan tool MB991958 screen is as shown in the figure.
OK: The display of the scan tool MB991958 is as shown in the figure.
Does scan tool MB991958 screen correspond to the illustration?
Repair the wiring harness between joint connector (CAN1) C-05 and A/C control panel connector C-216.
Check A/C control panel connector C-216, and repair if necessary. If the A/C control panel connector is in good condition, replace the A/C control panel.
 
STEP 25. Using scan tool MB991958, diagnose the CAN bus line. (trouble symptom check)
cautionStrictly observe the specified wiring harness repair procedure. For details refer to .
cautionTo prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
(1) Connect scan tool MB991958 to the data link connector. Refer to "How to connect the Scan Tool (M.U.T.-III) ."
(2) Turn the ignition switch to the "ON" position.
(3) Diagnose CAN bus lines, and check if the scan tool MB991958 screen is as shown in the figure.
OK: The display of the scan tool MB991958 is as shown in the figure.
Does scan tool MB991958 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 C-411, and repair if necessary. If the ETACS-ECU connector is in good condition, replace the ETACS-ECU.