ASC

DTC C2100: Abnormality in battery voltage (low voltage)

CAUTION:
^ If there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be set. Prior to this diagnosis, diagnose the CAN bus lines.
^ Whenever ECU is replaced, ensure that the CAN bus lines are normal.
^ When the hydraulic unit (integrated with ASC-ECU) is replaced, always carry out the calibration of the steering wheel sensor, the G and yaw rate sensor and brake fluid pressure sensor.

OPERATION
The ASC-ECU is energized by the valve power supply circuit (terminal No.32). When the power is supplied from the ignition switch (IG1) to the IG1 relay in ETACS-ECU, IG1 relay is turned on. At this time, the valve power supply circuit (terminal No.4) energizes the ASC-ECU.

DTC SET CONDITIONS
This diagnostic trouble code is set when the ASC-ECU power supply voltage drops below 9.7 ± 0.3 V during driving

PROBABLE CAUSES
^ Battery failure
^ Battery terminal looseness
^ Fusible link malfunction
^ Charging system failed
^ Damaged wiring harness and connectors
^ ASC-ECU malfunction DIAGNOSIS

Required Special Tools:
^ 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
^ MB991997: ASC check harness

STEP 1. M.U.T.-III CAN bus diagnosis
Use scan tool to diagnose the CAN bus lines.
Q: Is the check result normal?
YES: Go to Step 3.
NO: Repair the CAN bus lines. On completion, go to Step 2.

STEP 2. Diagnostic Trouble code recheck after resetting CAN bus lines
Q: Is DTC C2100 set?
YES: Go to Step 3.
NO: The procedure is complete.

STEP 3. Battery check
Refer to Battery Test.
Q: Is the battery in good condition?
YES: Go to Step 5.
NO: Charge or replace the battery, and then go to Step 4.

STEP 4. Charging system check
Refer to Output Current Test.
Q: Is the charging system in good condition?
YES: Go to Step 5.
NO: Repair or replace the charging system component(s).

STEP 5. Connector check: A-02 ASC-ECU connector
Q: Is the check result normal?
YES: Go to Step 6.
NO: Repair the defective connector.

STEP 6. Fusible link check: Check the fusible link No.27.
Q: Is the check result normal?
YES: Go to Step 8.
NO: Go to Step 7.

STEP 7. Resistance measurement at A-02 ASC-ECU connector

1) Removal the fusible link No.27.
2) Disconnect the ASC-ECU connector, connect special tool ASC check harness (MB991997) to the harness-side connector, and then measure the resistance at the special tool connector side.

NOTE: Do not connect the special tool ASC check harness (MB991997) to ASC-ECU.

3) Resistance between the terminal No.32 and the body ground.
OK: No continuity
Q: Is the check result normal?
YES: Replace the fusible link No.27.
NO: Repair the harness between the fusible link No.27 and A-02 ASC-ECU connector terminal No.32. Then replace the fusible link No.27.

STEP 8. Check the fuse No. 12.
Visually check the fuse No. 12 for open circuit.
Q: Is the check result normal?
YES: Go to Step 11.
NO: Go to Step 9.

STEP 9. Connector check: C-33 intermediate connector, C-317 ETACS-ECU connector
Q: Is the check result normal?
YES: Go to Step 10.
NO: Repair the defective connector.

STEP 10. Resistance measurement at A-02 ASC-ECU connector

1) Disconnect the C-317 ETACS-ECU connector.
2) Disconnect the ASC-ECU connector, connect special tool ASC check harness (MB991997) to the harness-side connector, and then measure the resistance at the special tool connector side.

NOTE: Do not connect the special tool ASC check harness (MB991997) to ASC-ECU.

3) Resistance between the terminal No.4 and the body ground.
OK: No continuity
Q: Is the check result normal?
YES: Replace the fuse No.12.
NO: Repair the harness between the C-317 ETACS-ECU connector terminal No.5 and A-02 ASC-ECU connector terminal No.4. Then replace the fuse No.12.

STEP 11. Check the fusible link No. 34.
Visually check the fuse No. 34 for open circuit.
Q: Is the check result normal?
YES: Go to Step 14.
NO: Go to Step 12.

STEP 12. Connector check: C-309 ETACS-ECU connector
Q: Is the check result normal?
YES: Go to Step 13.
NO: Repair the defective connector.

STEP 13. Resistance measurement at C-309 ETACS-ECU connector
1) Removal the fusible link No.34.
2) Disconnect the C-309 ETACS-ECU connector, and then measure the resistance at the connector side.
3) Resistance between the terminal No.1 and the body ground.
OK: No continuity
Q: Is the check result normal?
YES: Replace the fusible link No.34.
NO: Repair the harness between the fusible link No.34 and C-309 ETACS-ECU connector terminal No.1. Then replace the fusible link No.34.

STEP 14. Voltage measurement at the A-02 ASC-ECU connector

1) Disconnect the ASC-ECU connector, connect special tool ASC check harness (MB991997) to the harness-side connector, and then measure the voltage at the special tool connector side.

NOTE: Do not connect the special tool ASC check harness (MB991997) to ASC-ECU.

2) Measure the voltage between terminal No.32 and body ground.
OK: Approximately battery voltage
Q: Is the check result normal?
YES: Go to Step 15.
NO: Repair the wiring harness between the A-02 ASC-ECU connector terminal No. 32 and the fusible link No.27.

STEP 15. Connector check: C-309 ETACS-ECU connector
Q: Is the check result normal?
YES: Go to Step 16.
NO: Repair the defective connector.

STEP 16. Voltage measurement at the C-309 ETACS-ECU connector
1) Disconnect the connector, and measure at the wiring harness-side connector.
2) Measure the voltage between the terminal No.1 and the body ground.
OK: Approximately battery voltage
Q: Is the check result normal?
YES: Go to Step 17.
NO: Repair the wiring harness between C-309 ETACS-ECU connector terminal No. 1 and the fusible link No.34.

STEP 17. Connector check: C-317 ETACS-ECU connector
Q: Is the check result normal?
YES: Go to Step 18.
NO: Repair the defective connector.

STEP 18. Voltage measurement at the C-317 ETACS-ECU connector
1) Without disconnecting the connector, measure by backprobing.
2) Turn the ignition switch to the ON position.
3) Measure the voltage between the terminal No.6 and the body ground.
OK: Approximately battery voltage
Q: Is the check result normal?
YES: Go to Step 20.
NO: Go to Step 19.

STEP 19. Connector check: C-210 ignition switch connector
Q: Is the check result normal?
YES: Repair the wiring harness between the C-210 ignition switch connector terminal No. 2 and the C-317 ETACS-ECU connector terminal No. 6.
NO: Repair the defective connector.

STEP 20. Voltage measurement at the C-317 ETACS-ECU connector
1) Measure at ETACS-ECU-side connector.

NOTE: Do not disconnect the connector.

2) Turn the ignition switch to the ON position.
3) Measure the voltage between the terminal No.5 and the body ground.
OK: Approximately battery voltage
Q: Is the check result normal?
YES: Go to Step 21.
NO: Replace the ETACS-ECU. Then go to Step 25.

STEP 21. Connector check: C-33 intermediate connector
Q: Is the check result normal?
YES: Go to Step 22.
NO: Repair the defective connector.

STEP 22. Voltage measurement at the A-02 ASC-ECU connector

1) Disconnect the ASC-ECU connector, connect special tool ASC check harness (MB991997) to the harness-side connector, and then measure the resistance at the special tool connector side.

NOTE: Do not connect the special tool ASC check harness (MB991997) to ASC-ECU.

2) Resistance between terminal No.16 and body ground, and between terminal No.47 and body ground.
OK: Continuity exists (2 S2 or less)
Q: Is the check result normal?
YES: Go to Step 24.
NO: Repair the wiring harness between the A-02 ASC-ECU connector terminal No.16 and the body ground, and between the A-02 ASC-ECU connector terminal No.47 and the body ground.

STEP 24. Check whether the diagnostic Trouble code is reset.
Q: Is DTC C2100 set?
YES: Replace the ASC-ECU. Then go to Step 25.
NO: Intermittent malfunction.

STEP 25. Check whether the diagnostic Trouble code is reset.
Q: Is DTC C2100 set?
YES: Return to Step 1.
NO: This diagnosis is complete.