Code No.C1861:
Power supply 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.
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OPERATION
- The ABS-ECU is energised by the ignition switch (IG1) through J/B
fuse.
- Power supply for ABS solenoid valve is supplied to the ABS-ECU via fusible link.
- Power supply for ABS motor is supplied to the ABS-ECU via fusible link.
- The wheel speed sensors are energised via ABS-ECU.
DIAGNOSIS CODE SET CONDITION
This code is set if the solenoid valve power supply circuit drops abnormally.
PROBABLE CAUSES
- Damaged wiring harness or connector
- Battery abnormality
- Charging system failed
- ABS-ECU malfunction
- Battery terminal looseness
- Fusible link malfunction
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STEP 1. M.U.T.-III CAN bus diagnosis
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Use M.U.T.-III to diagnose the CAN bus lines.
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Q.
Is the check result normal?
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Go to Step 3.
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Repair the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ).
Then go to Step 2.
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STEP 2. Diagnosis code recheck after resetting CAN bus lines
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(1)Erase the diagnosis code.
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(2)Turn the ignition switch to the "LOCK" (OFF) position.
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(3)Turn the ignition switch to the "ON" position.
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(4)Check if the diagnosis code is set.
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Q.
Is diagnosis code No.C1861 set?
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Go to Step 3.
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This diagnosis is complete.
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STEP 3. Check the fusible link or the fuse.
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Visually check for open circuit in the fusible link or the fuse.
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Q.
Is the check result normal?
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Go to Step 4.
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Replace the fusible link or fuse. Then go to Step 9.
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Refer to GROUP 54A - Battery Test .
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Q.
Is the battery in good condition?
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Go to Step 5.
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Charge or replace the battery. Then go to Step 9.
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STEP 5. Charging system check
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Refer to GROUP 16 - Charging System .
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Q.
Is the charging system in good condition?
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Go to Step 6.
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Repair or replace the charging system component(s). Then go to Step 9.
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STEP 6. Resistance measurement at ABS-ECU connector
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(1)Disconnect the junction block connector.
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(2)Disconnect the fusible link.
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(3)Disconnect the ABS-ECU connector, and measure at the wiring harness-side connector.
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(4)Measure the resistance between the ABS-ECU connector +BV, +BM,
IG1 terminal and the body earth. OK: No continuity
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Q.
Is the check result normal?
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Go to Step 7.
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The short circuit may be present in the power supply circuit. Repair the damaged
connector or the wiring harness between the ABS-ECU connector +BV, +BM, IG1
terminal and the fusible link, the junction block connector terminal. Then go to Step 9.
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STEP 7. Voltage measurement at ABS-ECU connector
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(1)Disconnect the ABS-ECU connector.
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(2)Turn the ignition switch to the "ON" position.
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(3)Measure the resistance between the ABS-ECU connector +BV, +BM,
IG1 terminal and the body earth. OK: Battery voltage
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Q.
Is the check result normal?
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Go to Step 8.
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The open circuit may be present in the power supply circuit. Repair the damaged
connector or the wiring harness between the ABS-ECU connector +BV, +BM, IG1
terminal and the fusible link, the junction block connector terminal. Then go to Step 9.
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STEP 8. Check whether the diagnosis code is set again.
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(1)Erase the diagnosis code.
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(2)Turn the ignition switch to the "LOCK" (OFF) position.
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(3)Turn the ignition switch to the "ON" position.
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(4)Check if the diagnosis code is set.
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Q.
Is diagnosis code No. C1861 set?
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Replace the hydraulic unit [(integrated with ABS-ECU) Refer to ].
Then go to Step 9.
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Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent
Malfunctions ).
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STEP 9. Check whether the diagnosis code is set again.
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(1)Erase the diagnosis code.
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(2)Turn the ignition switch to the "LOCK" (OFF) position.
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(3)Turn the ignition switch to the "ON" position.
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(4)Check if the diagnosis code is set.
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Q.
Is diagnosis code No. C1861 set?
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Return to Step 1.
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This diagnosis is complete.
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