Code No.C1861: ABS-ECU power supply system malfunction (low voltage)









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 Diagnostics Table ).
  • Before replacing the ECU, ensure that the communication circuit is normal.

OPERATION



  • The ABS-ECU is energized by the ignition switch (IG1) through J/B fuse No.15 and the ABS-ECU terminal No.25.
  • Power supply for ABS solenoid valve is supplied to the ABS-ECU terminal No.1 via fusible link No.21.
  • Power supply for ABS motor is supplied to the ABS-ECU terminal No.13 via fusible link No.22.
  • The wheel speed sensors are energised via ABS-ECU terminal No. 25.

DIAGNOSIS CODE SET CONDITION



PROBABLE CAUSES



  • Damaged wiring harness or connector
  • Battery abnormality
  • Charging system failed
  • ABS-ECU malfunction
  • Battery terminal looseness

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 Diagnostics Table .). Then go to Step 2.

STEP 2. Diagnosis code recheck after resetting CAN bus lines
(1)Erase the diagnosis code.
(2)Turn the ignition switch to the "LOCK" (OFF) position.
(3)Turn the ignition switch to the "ON" position.
(4)Check if the diagnosis code is set.

Q. Is diagnosis code No.C1861 set?
Go to Step 3.
This diagnosis is complete.

STEP 3. Check the fusible link No.21, No.22 or the fuse No.15.
Visually check for open circuit in the fusible link No.21, No.22 or the fuse No.15.

Q. Is the check result normal?
Go to Step 4.
Replace the fusible link or fuse. Then go to Step 10.

STEP 4. Battery check
Refer to GROUP 54A - Battery Test .

Q. Is the battery in good condition?
Go to Step 5.
Charge or replace the battery. Then go to Step 10.

STEP 5. Charging system check
Refer to GROUP 16 - Charging System .

Q. Is the charging system in good condition?
Go to Step 6.
Repair or replace the charging system component(s). Then go to Step 10.

STEP 6. Connector check: A-01 ABS-ECU connector, C-207 junction block connector, C-210 junction block connector, C-307 ignition switch (IG1) connector

Q. Is the check result normal?
Go to Step 7.
NO : Repair the damaged connector. Then go to Step 10.

STEP 7. Resistance measurement at A-01 ABS-ECU connector
(1)Disconnect the C-210 junction block connector.
(2)Disconnect the fusible link No.21 and No.22.
(3)Disconnect the A-01 ABS-ECU connector, and measure at the wiring harness-side connector.
(4)Measure the resistance between the A-01 ABS-ECU connector terminal No.1, No.13, No.25 and the body earth.
OK: No continuity

Q. Is the check result normal?
Go to Step 8.
The short circuit may be present in the power supply circuit. Repair the wiring harness between the A-01 ABS-ECU connector terminal No.1, No.13, No.25 and the fusible link No.21, No.22, the C-210 junction block connector terminal No.8. Then go to Step 10.

STEP 8. Voltage measurement at A-01 ABS-ECU connector
(1)Disconnect the A-01 ABS-ECU connector.
(2)Turn the ignition switch to the "ON" position.
(3)Measure the resistance between the A-01 ABS-ECU connector terminal No.1, No.13, No.25 and the body earth.
OK: 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-01 ABS-ECU connector terminal No.1, No.13, No.25 and the fusible link No.21, No.22, the C-210 junction block connector terminal No.8. Then go to Step 10.

STEP 9. Check whether the diagnosis code is reset.
(1)Erase the diagnosis code.
(2)Turn the ignition switch to the "LOCK" (OFF) position.
(3)Turn the ignition switch to the "ON" position.
(4)Check if the diagnosis code is set.

Q. Is diagnosis code No. C1861 set?
Replace the hydraulic unit (integrated with ABS-ECU) (Refer to .). Then go to Step 10.
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunctions .).

STEP 10. Check whether the diagnosis code is reset.
(1)Erase the diagnosis code.
(2)Turn the ignition switch to the "LOCK" (OFF) position.
(3)Turn the ignition switch to the "ON" position.
(4)Check if the diagnosis code is set.

Q. Is diagnosis code No. C1861 set?
Return to Step 1.
This diagnosis is complete.