Anti-Lock Braking System (ABS)

DTC C2100: Abnormality in battery voltage (low voltage)

CAUTION:

- If there is any problem in the CAN bus lines, an incorrect DTC may be set. Prior to this diagnosis, diagnose the CAN bus lines CAN Bus Diagnostics Chart).

- Whenever ECU is replaced, ensure that the CAN bus lines are normal.

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 DTC is set in the following case.

- When the ABS-ECU power supply voltage drops below 9.7 ± 0.3 V while 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 A

- MB991974: ABS check harness

STEP 1. Using scan tool MB991958, diagnose the CAN bus line.

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 CAN Bus Diagnostics Chart).
On completion, and then go to Step 2.
STEP 2. DTC 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

Battery Test.

Q. Is the battery in good condition?

YES Go to Step 5.
NO Charge or replace the battery. Then go to Step 4.
STEP 4. Charging system check

Generator Output Line Voltage Drop 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-03 ABS-ECU connector, C-128 intermediate connector, C-212 ignition switch connector, C-309 ETACS-ECU connector, C-317 ETACS-ECU connector

Q. Is the check result normal?

YES Go to Step 6.
NO : Repair the damaged connector.
STEP 6. Fusible link check: Check fusible link No.27.

Visually check for open circuit in 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-03 ABS-ECU connector

(1)Removal the fusible link No.27.

(1)Disconnect the ASC-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 to ABS-ECU.

(2)Measure the voltage between terminal No.26 and body ground.
OK: Battery positive 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-03 ABS-ECU connector terminal No.26 and the fusible link No.27. Then go to Step 21.

STEP 9. Check the fuse No.12.

Visually check for open circuit in fuse No.12.

Q. Is the check result normal?

YES Go to Step 11.
NO Go to Step 10.
STEP 10. Resistance measurement at A-03 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 to ABS-ECU.

(3)Measure the 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-03 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 11. 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: Battery positive voltage

Q. Is the check result normal?

YES Go to Step 15.
NO Go to Step 12.
STEP 12. Fusible link check: Check the fusible link No.34.

Q. Is the check result normal?

YES Go to Step 14.
NO Go to Step 13.
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 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 14. Resistance measurement at fusible link No.34 and C-309 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 Intermittent malfunction 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 15. Resistance measurement at A-03 ABS-ECU connector

(1)Disconnect the C-317 ETACS-ECU connector.

(2)Disconnect the A-03 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 to ABS-ECU.

(3)Measure the resistance between the A-03 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 16.

NO The open circuit may be present in the power supply circuit. Repair the wiring harness between the A-03 ABS-ECU connector terminal No.7 and the C-317 ETACS-ECU connector terminal No.5. Then go to Step 21.

STEP 16. Measure the voltage at the C-317 ETACS-ECU connector.

(1)Measure by backprobing 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: Battery positive voltage

Q. Is the check result normal?

YES Go to Step 18.
NO Go to Step 17.
STEP 17. Resistance measurement at C-317 ETACS-ECU connector and the C-212 ignition switch connector

(1)Disconnect the C-317 ETACS-ECU connector and C-212 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-212 ignition switch connector terminal No.2.
OK: Continuity exists (2 ohms or less)

Q. Is the check result normal?

YES Go to Step 18.
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-212 ignition switch connector terminal No.2. Then go to Step 21.
STEP 18. Measure the voltage at the C-317 ETACS-ECU connector.

(1)Measure by backprobing without disconnecting 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 system voltage

Q. Is the check result normal?

YES Go to Step 20.
NO Go to Step 19.
STEP 19. Check whether the DTC is reset.

(1)Erase the DTC.

(2)Drive the vehicle at 12 mph (20 km/h) or higher.
NOTE:
The ABS warning light does not turn OFF in some cases unless the vehicle runs at 12 mph
(20 km/h) or higher.

Q. Is DTC C2100 set?

YES Replace the ETACS-ECU Electronic Time and Alarm Control System (ETACS)-ECU Removal and Installation). Then go to Step 20.
NO Intermittent malfunction How to Cope With Intermittent Malfunctions).
STEP 20. Check whether the DTC is reset.

(1)Erase the DTC.

(2)Drive the vehicle at 12 mph (20 km/h) or higher.
NOTE:
The ABS warning light does not turn OFF in some cases unless the vehicle runs at 12 mph
(20 km/h) or higher.

Q. Is DTC C2100 set?

YES Replace the hydraulic unit (integrated with ABS-ECU) (Refer to Anti-Lock Braking System (ABS)). Then go to Step 21.
NO Intermittent malfunction How to Cope With Intermittent Malfunctions).
STEP 21. Check whether the DTC is reset.

(1)Erase the DTC.

(2)Drive the vehicle at 12 mph (20 km/h) or higher.
NOTE:
The ABS warning light does not turn OFF in some cases unless the vehicle runs at 12 mph
(20 km/h) or higher.

Q. Is DTC C2100 set?

YES Return to Step 1.
NO The procedure is complete.