Diagnostic Item 14
DIAGNOSTIC ITEM 14: Diagnose CAN bus lines thoroughlyCAUTION: When 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.
Part 1:
Part 2:
TROUBLE JUDGMENT
If the M.U.T.-III cannot received signals from ECUs, CAN bus line connector(s) are broken or an open circuit has occurred.
COMMENTS ON TROUBLE SYMPTOM
The wiring harness wire or connectors may have loose, corroded, or damage terminals, or terminals pushed back in the connector, or an ECU may be defective.
TROUBLESHOOTING HINTS
- The wiring harness or connectors may have loose, corroded, or damage terminals, or terminals pushed back in the connector
- The ETACS-ECU may be defective
- The combination meter may be defective
- The A/C-ECU may be defective
- The SRS-ECU may be defective
- The TPMS receiver may be defective
- The powertrain control module may be defective
DIAGNOSIS
Required Special Tools:
- MB991223: Harness Set
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: Vehicle Communication Interface (V.C.I.)
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A
STEP 1. Check data link connector C-125 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
CAUTION: The strand end of the twisted wire should be within 10 cm (4 inches) from the connector.
Q: Is data link connector C-125 in good condition?
YES: Go to Step 2.
NO: Repair the damaged parts.
STEP 2. Check the CAN bus lines at the data link connector. Measure the resistance at the data link connector C-125.
CAUTION: A digital multimeter should be used.
CAUTION: The test wiring harness should be used.
1. Measure the resistance at the data link connector.
2. Turn the ignition switch to the "LOCK" (OFF) position.
CAUTION: Disconnect the negative battery terminal.
3. Disconnect the negative battery terminal.
4. Measure the resistance between data link connector terminals 6 and 14.
Q: How much resistance is measured?
2 ohms or less : Diagnostic Item 7: Check the CAN_L and H lines for a short circuit. Refer to DIAGNOSTIC ITEM 7.
No continuity : Diagnostic Item 10: Diagnose terminator resistors at both ends. Refer to DIAGNOSTIC ITEM 10.
More than 2 ohms but continuity exists : Go to Step 3.
STEP 3. Check intermediate connector C-29 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
CAUTION: The strand end of the twisted wire should be within 10 cm (4 inches) from the connector.
Q: Is intermediate connector C-29 in good condition?
YES: Go to Step 4.
NO: Repair the damaged parts.
STEP 4. Using scan tool MB991958, diagnose the CAN bus line (Disconnect intermediate connector C-29, and then determine that a failure is present at either the front wiring harness side or the instrument panel wiring harness side).
1. Disconnect intermediate connector C-29.
CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
2. Connect scan tool MB991958 to the data link connector.
3. Turn the ignition switch to the "ON" position.
4. Diagnose CAN bus lines, and check if the M.U.T.-III screen is as shown in the illustration.
5. Turn the ignition switch to the "LOCK" (OFF) position.
6. Connect intermediate connector C-29.
Q: Does the M.U.T.-III screen correspond to the illustration?
YES: If the M.U.T.-III screen corresponds to the illustration, go to STEP 21.
NO: If the M.U.T.-III screen does not correspond to the illustration, go to Step 5.
STEP 5. Check joint connector (3) C-02 and combination meter connector C-101 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
CAUTION: The strand end of the twisted wire should be within 10 cm (4 inches) from the connector.
Check the joint connector at the wiring harness side for loose, corroded or damaged terminals, or terminals pushed back in the connector, and also check the short pin behind the connector for corrosion, deformation and delamination.
Q: Is joint connector (3) C-02 in good condition?
YES: Go to Step 6.
NO: Repair the damaged parts. Replace the joint connector as necessary.
STEP 6. Using scan tool MB991958, diagnose the CAN bus line (Disconnect combination meter connector C-101, and check the combination meter system).
1. Disconnect combination meter connector C-101.
2. Turn the ignition switch to the "ON" position.
3. Diagnose CAN bus lines, and check if the M.U.T.-III screen is as shown in the illustration.
4. Turn the ignition switch to the "LOCK" (OFF) position.
5. Disconnect combination meter connector C-101.
Q: Does the M.U.T.-III screen correspond to the illustration?
YES: If the M.U.T.-III screen corresponds to the illustration, go to Step 7.
NO: If the M.U.T.-III screen does not correspond to the illustration, go to Step 8.
STEP 7. Check the CAN bus lines between joint connector (3) and the combination meter. Measure the resistance between joint connector (3) C-02 and combination meter connector C-101.
CAUTION: A digital multimeter should be used.
CAUTION: The test wiring harness should be used.
1. Disconnect joint connector (3) C-02 and combination meter connector C-101, and measure the resistance between each wiring harness side connector.
2. Turn the ignition switch to the "LOCK" (OFF) position.
CAUTION: Disconnect the negative battery terminal.
3. Disconnect the negative battery terminal.
4. Measure the resistance between joint connector (3) terminal 15 and combination meter connector terminal 15.
OK: 2 ohms or less
5. Measure the resistance between joint connector (3) terminal 4 and combination meter connector terminal 14.
OK: 2 ohms or less
CAUTION: Strictly observe the specified wiring harness repair procedure.
Q: Do all the resistances measure 2 ohms or less?
YES: If all the resistances measure 2 ohms or less, power supply to the combination meter may be suspected. Diagnose the combination meter by referring to Chassis Electrical, Combination meter assembly.
NO: If either of the resistances measures more than 2 ohms or all the resistances measure more than 2 ohms, repair the wiring harness between joint connector (3) and the combination meter connector.
STEP 8. Check ETACS-ECU connector C-218 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
CAUTION: The strand end of the twisted wire should be within 10 cm (4 inches) from the connector.
Q: Is ETACS-ECU connector C-218 in good condition?
YES: Go to Step 9.
NO: Repair the damaged parts.
STEP 9. Using scan tool MB991958, diagnose the CAN bus line (Disconnect ETACS-ECU connector C-218, and check the ETACS-ECU system).
1. Disconnect ETACS-ECU connector C-218.
2. Turn the ignition switch to the "ON" position.
3. Diagnose CAN bus lines, and check if the M.U.T.-III screen is as shown in the illustration.
4. Turn the ignition switch to the "LOCK" (OFF) position. 5. Connect ETACS-ECU connector C-218.
Q: Does the M.U.T.-III screen correspond to the illustration?
YES: If the M.U.T.-III screen corresponds to the illustration, go to Step 10.
NO: If the M.U.T.-III screen does not correspond to the illustration, go to Step 11.
STEP 10. Check the CAN bus lines between joint connector (3) and the ETACS-ECU. Measure the resistance between joint connector (3) C-02 and ETACS-ECU connector C-218.
CAUTION: A digital multimeter should be used.
CAUTION: The test wiring harness should be used.
1. Disconnect joint connector (3) C-02 and ETACS-ECU connector C-218, and measure the resistances at the wiring harness sides of joint connector (3) C-02 and ETACS-ECU connector C-218.
2. Turn the ignition switch to the "LOCK" (OFF) position.
CAUTION: Disconnect the negative battery terminal.
3. Disconnect the negative battery terminal.
4. Measure the resistance between joint connector (3) terminal 16 and ETACS-ECU connector terminal 73.
OK: 2 ohms or less
5. Measure the resistance between joint connector (3) terminal 5 and ETACS-ECU connector terminal 72.
OK: 2 ohms or less
CAUTION: Strictly observe the specified wiring harness repair procedure.
Q: Do all the resistances measure 2 ohms or less?
YES: If all the resistances measure 2 ohms or less, power supply to the ETACS-ECU may be suspected. Diagnose the ETACS-ECU by referring to Information Bus, Diagnosis.
NO: If either of the resistances measures more than 2 ohms or all the resistances measure more than 2 ohms, repair the wiring harness between joint connector (3) and the ETACS-ECU connector.
STEP 11. Check A/C-ECU connector C-10
CAUTION: The strand end of the twisted wire should be within 10 cm (4 inches) from the connector.
Q: Is A/C-ECU connector C-10
YES: Go to Step 12.
NO: Repair the damaged parts.
STEP 12. Using scan tool MB991958, diagnose the CAN bus line (Disconnect A/C-ECU connector C-10
1. Disconnect A/C-ECU connector C-10
2. Turn the ignition switch to the "ON" position.
3. Diagnose CAN bus lines, and check if the M.U.T.-III screen is as shown in the illustration.
4. Turn the ignition switch to the "LOCK" (OFF) position.
5. Connect A/C-ECU connector C-10
Q: Does the M.U.T.-III screen correspond to the illustration?
YES: If the M.U.T.-III screen corresponds to the illustration, go to Step 13.
NO: If the M.U.T.-III screen does not correspond to the illustration, go to Step 14.
STEP 13. Check the CAN bus lines between joint connector (3) and the A/C-ECU. Measure the resistance between joint connector (3) C-02 and A/C-ECU connector C-10
CAUTION: A digital multimeter should be used.
CAUTION: The test wiring harness should be used.
1. Disconnect joint connector (3) C-02 and A/C-ECU connector C-10
2. Turn the ignition switch to the "LOCK" (OFF) position.
CAUTION: Disconnect the negative battery terminal.
3. Disconnect the negative battery terminal.
4. Measure the resistance between joint connector (3) terminal 17 and A/C-ECU connector terminal 6
OK: 2 ohms or less
5. Measure the resistance between joint connector (3) terminal 6 and A/C-ECU connector terminal 5
OK: 2 ohms or less
CAUTION: Strictly observe the specified wiring harness repair procedure.
Q: Do all the resistances measure 2 ohms or less?
YES: If all the resistances measure 2 ohms or less, power supply to the A/C-ECU may be suspected. Diagnose the air conditioning system. Refer to Heater and A/C, Manual A/C diagnosis.
NO: If either of the resistances measures more than 2 ohms or all the resistances measure more than 2 ohms, repair the wiring harness between joint connector (3) and the A/C-ECU connector.
STEP 14. Check SRS-ECU connector C-121 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
CAUTION: The strand end of the twisted wire should be within 10 cm (4 inches) from the connector.
Q: Is SRS-ECU connector C-121 in good condition?
YES: Go to Step 15.
NO: Repair the damaged parts.
STEP 15. Using scan tool MB991958, diagnose the CAN bus line (Disconnect SRS-ECU connector C-121, and check the supplemental restraint system).
1. Disconnect SRS-ECU connector C-121.
2. Turn the ignition switch to the "ON" position.
3. Diagnose CAN bus lines, and check if the M.U.T.-III screen is as shown in the illustration.
4. Turn the ignition switch to the "LOCK" (OFF) position. 5. Connect the SRS-ECU connector C-121.
Q: Does the M.U.T.-III screen correspond to the illustration?
YES: If the M.U.T.-III screen corresponds to the illustration, go to Step 16.
NO: If the M.U.T.-III screen does not correspond to the illustration, go to Step 17.
STEP 16. Check the CAN bus lines between joint connector (3) and the SRS-ECU. Measure the resistance between joint connector (3) C-02 and SRS-ECU connector C-121.
CAUTION: A digital multimeter should be used.
CAUTION: The test wiring harness should be used.
1. Disconnect joint connector (3) C-02 and SRS-ECU connector C-121, and measure the resistances at the wiring harness sides of joint connector (3) C-02 and SRS-ECU connector C-121.
2. Turn the ignition switch to the "LOCK" (OFF) position.
CAUTION: Disconnect the negative battery terminal.
3. Disconnect the negative battery terminal.
4. Measure the resistance between joint connector (3) terminal 3 and SRS-ECU connector terminal 32.
OK: 2 ohms or less
5. Measure the resistance between joint connector (3) terminal 14 and SRS-ECU connector terminal 43.
OK: 2 ohms or less
CAUTION: Strictly observe the specified wiring harness repair procedure.
Q: Do all the resistances measure 2 ohms or less?
YES: If all the resistances measure 2 ohms or less, power supply to the SRS-ECU may be suspected. Diagnose the supplemental restraint system. Refer to SRS, SRS air bag diagnosis, equipment diagnosis.
NO: If either of the resistances measures more than 2 ohms or all the resistances measure more than 2 ohms, repair the wiring harness between joint connector (3) and the SRS-ECU connector.
STEP 17. Check TPMS receiver connector C-133 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
CAUTION: The strand end of the twisted wire should be within 10 cm (4 inches) from the connector.
Q: Is TPMS receiver connector C-133 in good condition?
YES: Go to Step 18.
NO: Repair the damaged parts.
STEP 18. Using scan tool MB991958, diagnose the CAN bus line (Disconnect TPMS receiver connector C-133, and check the supplemental restraint system).
1. Disconnect TPMS receiver connector C-133.
2. Turn the ignition switch to the "ON" position.
3. Diagnose CAN bus lines, and check if the M.U.T.-III screen is as shown in the illustration.
4. Turn the ignition switch to the "LOCK" (OFF) position.
5. Connect the TPMS receiver connector C-133.
Q: Does the M.U.T.-III screen correspond to the illustration?
YES: If the M.U.T.-III screen corresponds to the illustration, go to Step 19.
NO: If the M.U.T.-III screen does not correspond to the illustration, go to Step 20.
STEP 19. Check the CAN bus lines between joint connector (3) and the TPMS receiver. Measure the resistance between joint connector (3) C-02 and TPMS receiver connector C-133.
CAUTION: A digital multimeter should be used.
CAUTION: The test wiring harness should be used.
1. Disconnect joint connector (3) C-02 and TPMS receiver connector C-133, and measure the resistances at the wiring harness sides of joint connector (3) C-02 and TPMS receiver connector C-133.
2. Turn the ignition switch to the "LOCK" (OFF) position.
CAUTION: Disconnect the negative battery terminal.
3. Disconnect the negative battery terminal.
4. Measure the resistance between joint connector (3) terminal 10 and TPMS receiver connector terminal 1.
OK: 2 ohms or less
5. Measure the resistance between joint connector (3) terminal 21 and TPMS receiver connector terminal 2.
OK: 2 ohms or less
CAUTION: Strictly observe the specified wiring harness repair procedure.
Q: Do all the resistances measure 2 ohms or less?
YES: If all the resistances measure 2 ohms or less, power supply to the TPMS receiver may be suspected. Diagnose the supplemental restraint system. Refer to SRS, SRS air bag diagnosis, equipment diagnosis.
NO: If either of the resistances measures more than 2 ohms or all the resistances measure more than 2 ohms, repair the wiring harness between joint connector (3) and the TPMS receiver connector.
STEP 20. Check the CAN bus lines between joint connector (3) and the data link connector. Measure the resistance between joint connector (3) C-02 and data link connector C-125.
CAUTION: A digital multimeter should be used.
CAUTION: The test wiring harness should be used.
1. Disconnect joint connector (3) C-02, and measure the resistance between the wiring harness side connector of joint connector (3) C-02 and wiring harness side connector of data link connector C-125.
2. Turn the ignition switch to the "LOCK" (OFF) position.
CAUTION: Disconnect the negative battery terminal.
3. Disconnect the negative battery terminal.
4. Measure the resistance between joint connector (3) terminal 18 and data link connector terminal 14.
OK: 2 ohms or less
5. Measure the resistance between joint connector (3) terminal 7 and data link connector terminal 6.
OK: 2 ohms or less
CAUTION: Strictly observe the specified wiring harness repair procedure.
Q: Do all the resistances measure 2 ohms or less?
YES: If all the resistances measure 2 ohms or less, refer to diagnostics item 7: Check the CAN_L and H lines for a short circuit (Refer to DIAGNOSTIC ITEM 14).
NO: If all the resistances measure 2 ohms or less, repair the wiring harness between joint connector (3) and the data link connector.
STEP 21. Check powertrain control module connector B-19 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
CAUTION: The strand end of the twisted wire should be within 10 cm (4 inches) from the connector.
Q: Is powertrain control module connector B-19 in good condition?
YES: Go to STEP 22.
NO: Repair the damaged parts.
STEP 22. Using scan tool MB991958, diagnose the CAN bus line (Disconnect powertrain control module connector B-19, and check the powertrain control module system).
1. Disconnect powertrain control module connector B-19.
2. Turn the ignition switch to the "ON" position.
3. Diagnose CAN bus lines, and check if the M.U.T.-III screen is as shown in the illustration.
4. Turn the ignition switch to the "LOCK" (OFF) position.
5. Connect powertrain control module connector B-19.
Q: Does the M.U.T.-III screen correspond to the illustration?
YES: If the M.U.T.-III screen corresponds to the illustration, go to STEP 23.
NO: If the M.U.T.-III screen does not correspond to the illustration, refer to diagnostics item 7: Check the CAN_L and H lines for a short circuit (Refer to DIAGNOSTIC ITEM 7).
STEP 23. Check the CAN bus lines between intermediate connector C-29 and the powertrain control module. Measure the resistance between intermediate connector C-29 and powertrain control module connector B-19.
CAUTION: A digital multimeter should be used.
CAUTION: The test wiring harness should be used.
1. Disconnect intermediate connector C-29 and powertrain control module connector B-19, and measure the resistance between the wiring harness side connector of powertrain control module connector B-19 and the male side connector of intermediate connector C-29 (at front wiring harness side).
2. Turn the ignition switch to the "LOCK" (OFF) position.
CAUTION: Disconnect the negative battery terminal.
3. Disconnect the negative battery terminal.
4. Measure the resistance between intermediate connector terminal 11 and powertrain control module connector terminal 17.
OK: 2 ohms or less
5. Measure the resistance between intermediate connector terminal 12 and powertrain control module connector terminal 18.
OK: 2 ohms or less
CAUTION: Strictly observe the specified wiring harness repair procedure.
Q: Do all the resistances measure 2 ohms or less?
YES: If all the resistances measure 2 ohms or less, go to STEP 24.
NO: If either of the resistances measures more than 2 ohms or all the resistances measure more than 2 ohms, repair the wiring harness between intermediate connector C-29 and the powertrain control module connector.
STEP 24. Check the CAN bus lines between intermediate connector C-29 and the joint connector (3). Measure the resistance between intermediate connector C-29 and joint connector (3) C-02.
CAUTION: A digital multimeter should be used.
CAUTION: The test wiring harness should be used.
1. Disconnect joint connector (3) C-02 and intermediate connector C-29, and measure the resistance between the wiring harness side connector of joint connector (3) C-02 and the female side connector of intermediate connector C-29 (instrument panel wiring harness side).
2. Turn the ignition switch to the "LOCK" (OFF) position.
CAUTION: Disconnect the negative battery terminal.
3. Disconnect the negative battery terminal.
4. Measure the resistance between joint connector (3) terminal 20 and intermediate connector terminal 12.
OK: 2 ohms or less
5. Measure the resistance between joint connector (3) terminal 9 and intermediate connector C-29 terminal 11.
OK: 2 ohms or less
CAUTION: Strictly observe the specified wiring harness repair procedure.
Q: Do all the resistances measure 2 ohms or less?
YES: If all the resistances measure 2 ohms or less, power supply to the powertrain control module may be suspected. Diagnose the engine. Refer to MFI, MFI diagnosis <2.4L engine> or MFI diagnosis <3.8L engine>.
NO: If either of the resistances measures more than 2 ohms or all the resistances measure more than 2 ohms, repair the wiring harness between joint connector (3) and the intermediate connector.