Code No. C2116 Low power supply voltage in pump motor








caution
  • If there is any problem in the CAN bus lines, an incorrect diagnosis code may be set. Prior to this diagnosis, diagnose the CAN bus lines (Refer to GROUP 54C, CAN Bus Diagnosis Table ).
  • 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 (Refer to , and ).

OPERATION

  • ASC-ECU contains the power supply circuit (terminal No.1) for the pump motor. The pump motor is energised by the motor switch, which is incorporated in ASC-ECU.
  • The pump motor switch, which is incorporated in ASC-ECU, is always off unless the motor solenoid valve check is activated when the vehicle is started.
  • ASC-ECU activates the pump motor by turning on the ECU built-in pump motor switch.

DIAGNOSIS CODE SET CONDITIONS
This diagnosis codes will be set under the cases below:

  • When the power supply voltage of the pump motor, which is not in operation, is abnormally low for a prolonged period
  • When the power supply voltage of the pump motor, which is not in operation, is abnormally high for a prolonged period

PROBABLE CAUSES
Current trouble
  • Fusible link malfunction
  • Damaged wiring harness and connectors
  • Abnormality in battery or alternator
  • ASC-ECU malfunction
Past trouble
  • Carry out diagnosis with particular emphasis on wiring harness and connector failures between the power supply circuit (A-58 ASC-ECU connector terminal No.1) to the ASC-ECU motor and the earth circuit (A-58 ASC-ECU connector terminal No.16 and 47). For diagnosis procedures, refer to How to treat past trouble (GROUP 00 - How to Use Troubleshooting/Inspection Service Points ).

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnosis
Use M.U.T.-III to diagnose the CAN bus lines.

Q. Is the check result normal?
Go to Step 3.
Repair the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnosis table ). On completion, go to Step 2.

STEP 2. Diagnosis code recheck after resetting CAN bus lines

Q. Is the diagnosis code No. C2116 set?
Go to Step 3.
This diagnosis is complete.

STEP 3. Battery check
Refer to GROUP 54A - Battery Test .

Q. Is the battery in good condition?
Go to Step 4.
Replace the battery. Then go to Step 11.

STEP 4. Charging system check
Refer to GROUP 16 - Charging System <4A9>, <4B1>, <BWC>, <4B1-T/C>.

Q. Is the charging system in good condition?
Go to Step 5.
Repair or replace the charging system component(s). Then go to Step 11.

STEP 5. Connector check: A-58 ASC-ECU connector

Q. Is the check result normal?
Go to Step 6.
NO : Repair the defective connector. Then go to Step 11.

STEP 6. Fusible link check: Check the fusible link No.26.
Visually check for open circuit in the fusible link No.26.

Q. Is the check result normal?
Go to Step 8.
Go to Step 7.

STEP 7. Resistance measurement at A-58 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)Disconnect the fusible link No.26.
(3)Resistance between the terminal No.1 and the body earth.
OK: No continuity

Q. Is the check result normal?

Replace the fusible link No.26. Then go to Step 11.

The short circuit may be present in the power supply circuit. Repair the wiring harness between the A-58 ASC-ECU connector terminal No.1 and the fusible link No.26, and then replace the fusible link No.26. Then go to Step 11.

STEP 8. Voltage measurement at the A-58 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 the terminal No.1 and the body earth.
OK: Approximately battery voltage

Q. Is the check result normal?

Go to Step 9.

The open circuit may be present in the power supply circuit. Repair the wiring harness between the A-58 ASC-ECU connector terminal No.1 and the fusible link No.26. Then go to Step 11.

STEP 9. Resistance measurement at A-58 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 the terminal No.16 and the body earth, and between the terminal No.47 and the body earth.
OK: Continuity exists (2 Ω or less)

Q. Is the check result normal?

Go to Step 10.

An open circuit may be present in the earth circuit. Repair the wiring harness between the A-58 ASC-ECU connector terminal No.16 and the body earth, and between the A-58 ASC-ECU connector terminal No.47 and the body earth. Then go to Step 11.

STEP 10. Check whether the diagnosis code is reset.
(1)Erase the diagnosis code.
(2)Drive the vehicle at 20 km/h or more.
note The ABS warning lamp does not turn OFF in some cases unless the vehicle runs at 20 km/h or higher.

Q. Is the diagnosis code No. C2116 set?
Replace the hydraulic unit (ASC-ECU) (Refer to ). Then go to Step 11.
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).

STEP 11. Check whether the diagnosis code is reset.
(1)Erase the diagnosis code.
(2)Drive the vehicle at 20 km/h or more.
note The ABS warning lamp does not turn OFF in some cases unless the vehicle runs at 20 km/h or higher.

Q. Is the diagnosis code No. C2116 set?
Return to Step 1.
This diagnosis is complete.