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Home >> Mitsubishi >> 2006 >> Galant L4-2.4L (4G69) >> Repair and Diagnosis >> Powertrain Management >> Computers and Control Systems >> Information Bus >> Testing and Inspection >> Component Tests and General Diagnostics >> Diagnostic Item 15 >> Part 2

Part 2

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 19.




STEP 16. Check intermediate connector C-22 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-22 in good condition?

YES: Go to Step 17.

NO: Repair the damaged parts.

STEP 17. Check the CAN bus lines between intermediate connector and the SRS-ECU. Measure the resistance between intermediate connector C-22 and SRS-ECU connector C-121.

CAUTION: A digital multimeter should be used.

CAUTION: The test wiring harness should be used.




1. Disconnect intermediate connector C-22 and SRS-ECU connector C-121, and measure the resistance at the wiring harness sides of intermediate connector C-22 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 intermediate connector terminal 22 and SRS-ECU connector terminal 32.

OK: 2 ohms or less




5. Measure the resistance between intermediate connector terminal 23 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, go to Step 18.

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 and the SRS-ECU connector.

STEP 18. Check the CAN bus lines between joint connector (3) and the intermediate connector. Measure the resistance between joint connector (3) C-02 and intermediate connector C-22.

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-22, and measure the resistance at the wiring harness sides of joint connector (3) C-02 and intermediate connector C-22.
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 intermediate connector terminal 22.

OK: 2 ohms or less




5. Measure the resistance between joint connector (3) terminal 14 and intermediate connector terminal 23.

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 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 intermediate connector.

STEP 19. 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 8: Check the CAN_L and H lines for a short circuit.

NO: If all the resistances measure 2 ohms or less, repair the wiring harness between joint connector (3) and the data link connector.







STEP 20. Check ABS-ECU connector A-02 and 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: Are ABS-ECU connector A-02 and powertrain control module connector B-19 in good condition?

YES: Go to Step 21.

NO: Repair the damaged parts.

STEP 21. 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 22.

NO: If the M.U.T.-III screen does not correspond to the illustration, go to Step 24.

STEP 22. Check the CAN bus lines between the ABS-ECU and the powertrain control module. Measure the resistance between ABS-ECU connector A-02 and powertrain control module connector B-19.

CAUTION: A digital multimeter should be used.

CAUTION: The test wiring harness should be used.







1. Disconnect ABS-ECU connector A-02 and powertrain control module connector B-19, 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 ABS-ECU connector terminal 23 and powertrain control module connector terminal 18.

OK: 2 ohms or less




5. Measure the resistance between ABS-ECU connector terminal 24 and powertrain control module connector terminal 17.

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 23.

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 ABS-ECU connector and the powertrain control module connector.

STEP 23. Check the CAN bus lines inside the ABS-ECU. Measure the resistance at ABS-ECU connector A-02.

CAUTION: A digital multimeter should be used.

CAUTION: The test wiring harness should be used.




1. Disconnect ABS-ECU connector A-02, and measure the resistance at the component side of ABS-ECU connector A-02.
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 ABS-ECU connector terminals 7 and 23.

OK: 2 ohms or less




5. Measure the resistance between ABS-ECU connector terminals 24 and 25.

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 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, replace the ABS-ECU.

STEP 24. Using scan tool MB991958, diagnose the CAN bus line (Disconnect ABS-ECU connector A-02, and check the ABS-ECU system).




1. Disconnect ABS-ECU connector A-02.
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. Check ABS-ECU connector A-02.

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 25.

NO: If the M.U.T.-III screen does not correspond to the illustration, refer to diagnostics item 8: Check the CAN_L and H lines for a short circuit.

STEP 25. Check the CAN bus lines between intermediate connector C-29 and the ABS-ECU. Measure the resistance between intermediate connector C-29 and ABS-ECU connector A-02.

CAUTION: A digital multimeter should be used.

CAUTION: The test wiring harness should be used.







1. Disconnect intermediate connector C-29 and ABS-ECU connector A-02, and measure the resistance between the wiring harness side connector of ABS-ECU connector A-02 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 ABS-ECU connector terminal 25.

OK: 2 ohms or less




5. Measure the resistance between intermediate connector terminal 12 and ABS-ECU connector terminal 7.

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 26.

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 ABS-ECU connector.

STEP 26. 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 intermediate connector terminal 11 and joint connector (3) terminal 9.

OK: 2 ohms or less




5. Measure the resistance between intermediate connector terminal 12 and joint connector (3) terminal 20.

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 ABS-ECU may be suspected. Diagnose the ABS system. Refer to ABS diagnosis in Antilock Brakes/Traction Control Systems.

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 intermediate connector C-29.
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