ABS

The contents of this article and images reflect the changes identified in TSB-11-35-006.

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.

CIRCUIT OPERATION
The ABS-ECU is energized by the valve power supply circuit (terminal No.26).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.26) energizes the ABS-ECU.

DTC SET CONDITIONS
This diagnostic trouble code is set when the ABS-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
^ ABS-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
^ MB991974: ABS check harness

STEP 1. M.U.T.-III CAN bus diagnostics
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. Fusible link check: Check the fusible link No. 27.
Visually check for open circuit in the fusible link No. 27.
Q: Is the check result normal?
YES: Go to Step 4.
NO: Replace the fusible link No. 27.

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

STEP 5. Charging system check
Refer to Output Current Test.
Q: Is the charging system in good condition?
YES: Go to Step 6.
NO: Repair or replace the charging system component(s).

STEP 6. Voltage measurement at the A-01 ABS-ECU connector

1) Disconnect the connector, connect special tool ABS check harness (MB991974) to the harness-side connector, and measure the voltage at the special tool connector side.

NOTE: Do not connect the special tool ABS check harness (M8991974) to ABS-ECU.

2) Turn the ignition switch to the ON position.
3) Measure the voltage between the terminal No.26 and the body ground.
OK: Approximately battery voltage
Q: Is the check result normal?
YES: Go to Step
8. NO: Go to Step 7.

STEP 7. Resistance measurement at A-01 ABS-ECU connector
1) Removal the fusible link No. 27.

1) Disconnect the ABS-ECU connector, connect special tool ABS check harness (MB991974) to the harness-side connector, and then measure the voltage at the special tool connector side.

NOTE: Do not connect the special tool ABS check harness (MB991974) to ABS-ECU.

2) Measure the voltage between terminal No. 26 and body ground.
OK: Approximately system voltage.

Q: Is the check result normal?
YES: Go to Step 9.
NO: The open circuit may be present in the power supply circuit. Repair the wiring harness between the A-01 ABS-ECU connector terminal No. 26 and the fusible link No. 27. Then go to Step 21.

STEP 9. Voltage measurement at the A-01 ABS-ECU connector

1) Disconnect the ABS-ECU connector, connect special tool ABS check harness (MB991974) to the harness-side connector, and then measure the voltage at the special tool connector side.

NOTE: Do not connect the special tool ABS check harness (MB991974) to ABS-ECU.

2) Turn the ignition switch to the 'ON' position.
3) Measure the voltage between terminal No. 7 and body ground.
OK: Approximately system voltage.

Q: Is the check result normal?
YES: Go to Step 20.
NO: Go to Step 10.

STEP 10. Check the fuse No. 12.
Visually check for open circuit in fuse No. 12.

Q: Is the check result normal?
YES: Go to Step 12.
NO: Go to Step 11.

STEP 11. Resistance measurement at A-01 ABS-ECU connector
1) Disconnect the C-317 ETACS-ECU connector.

2) Disconnect the ABS-ECU connector, connect special tool ABS check harness (MB991974) to the harness-side connector, and then measure the resistance at the special tool connector side.

NOTE: Do not connect the special tool ABS check harness (MB991974) to ABS-ECU.

3) Resistance between the terminal No. 7 and the body ground.
OK: No continuity

Q: Is the check result normal?
YES: Replace the fuse No. 12. Then go to Step 21.
NO: The short circuit may be present in the power supply circuit. Repair the wiring harness between the A-01 ABS-ECU connector terminal No. 7 and the C-317 ETACS-ECU connector terminal No. 5, and then replace the fuse No. 12. Then go to Step 21.

STEP 12. Measure the voltage 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 system voltage

Q: Is the check result normal?
YES: Go to Step 15.
NO: Go to Step 13.

STEP 13. Fusible link check: Check the fusible link No. 34.

Q: Is the check result normal?
YES: Go to Step 15.
NO: Go to Step 14.

STEP 14. Resistance measurement at C-309 ETACS-ECU connector
1) Removal the fusible link No. 34.
2) Disconnect the C309 ETACS-ECU connector, and then measure the resistance at the harness connector side.
3) Measure the 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. Then go to Step 21.
NO: The short circuit may be present in the power supply circuit. Repair the wiring harness between the C-309 ETACS-ECU connector terminal No. 1 and the fusible link No. 34, and then replace the fusible link No. 34. Then go to Step 21.

STEP 15. Resistance measurement at fusible link No. 34 and C309 ETACS-ECU connector
1) Disconnect the C-309 ETACS-ECU connector and fusible link No. 34, and then measure the resistance at the harness connector side.
2) Measure the resistance between the fusible link No. 34 and C-309 ETACS-ECU connector terminal No. 1.
OK: Continuity exists (2 Ohms or less)

Q: Is the check result normal?
YES: Go to Step 16.
NO: The open circuit may be present in the power supply circuit. Repair the wiring harness between the fusible link No. 34 and C-309 ETACS-ECU connector terminal No. 1. Then go to Step 21.

STEP 16. Resistance measurement at A-01 ABS-ECU connector
1) Disconnect the C-317 ETACS-ECU connector.

2) Disconnect the A-01 ABS-ECU connector, connect special tool ABS check harness (MB991974) to the harness-side connector, and then measure the resistance at the special tool connector side.

NOTE: Do not connect the special tool ABS check harness (MB991974) to ABS-ECU.

3) Measure the resistance between the A-01 ABS-ECU connector terminal No. 7 and the C-317 ETACS-ECU connector terminal No. 5.
OK: Continuity exists (2 Ohms or less)

Q: Is the check result normal?
YES: Go to Step 17.
NO: The open circuit may be present in the power supply circuit. Repair the wiring harness between the A-01 ABS-ECU connector terminal No. 7 and the C-317 ETACS-ECU connector terminal No. 5. Then go to Step 21.

STEP 17. Measure the voltage at the C-317 ETACS-ECU connector.
1) Measure by back probing without disconnecting the connector.
2) Turn the ignition switch to the ON position.
3) Measure the voltage between the terminal No. 6 and the body ground.
OK: Approximately system voltage

Q: Is the check result normal?
YES: Go to Step 20.
NO: Go to Step 18.

STEP 18. Resistance measurement at C-317 ETACS-ECU connector and the C-210 ignition switch connector
1) Disconnect the C-317 ETACS-ECU connector and C-210 ignition switch connector, and then measure the resistance at the harness connector side.
2) Measure the resistance between the C-317 ETACS-ECU connector terminal No. 6 and C-210 ignition switch connector terminal No. 2.
OK: Continuity exists (2 Ohms or less)

Q: Is the check result normal?
YES: Diagnose the ignition switch, then go to Step 21.
NO: The open circuit may be present in the power supply circuit. Repair the wiring harness between the C-317 ETACS-ECU connector terminal No. 6 and C-210 ignition switch connector terminal No. 2. Then go to Step 19.

STEP 19. Check whether the DTC is reset.
1) Erase the DTC.
2) Drive the vehicle at 12 MPH(20km/h) or higher.

Q: Is the DTC C2100 set?
YES: Replace the ETACS-ECU. Then go to Step 20.
NO: Intermittent malfunction.

STEP 20. Check whether the DTC is reset.
1) Erase the DTC.
2) Drive the vehicle at 12 MPH(20km/h) or higher.

Q: Is the DTC C2100 set?
YES: Replace the hydraulic unit. Then go to Step 21.
NO: Intermittent malfunction.

STEP 21. Check whether the DTC is reset.
1) Erase the DTC.
2) Drive the vehicle at 12 MPH(20km/h) or higher.

Q: Is the DTC C2100 set?
YES: Return to Step 1.
NO: This diagnosis is complete.