Code No. C1861:
Power supply low voltage
OPERATION
The electric parking brake ECU is energised from the battery through the fusible links.
DIAGNOSIS CODE SET CONDITIONS
If the parking brake is not applied or released within a predetermined period due to a
low battery voltage, the diagnosis code will be set.
PROBABLE CAUSES
- Battery not charged sufficiently or deteriorated
- Loose or contaminated battery terminals
- Open or earth fault in the electric parking brake ECU power supply circuit.
- Malfunction of the electric parking brake ECU
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STEP 1. Check the battery.
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Refer to GROUP 54A - Fluid Level And Specific Gravity Check, Battery Test.
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Q.
Is the check result normal?
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 Go to Step 2.
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 Charge or replace the battery (Refer to GROUP 54A - Battery). Then go
to Step 3.
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STEP 2. Check the charging system.
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Refer to GROUP 16 - Charging System.
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Q.
Is the check result normal?
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Go to Step 3.
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Repair or replace the charging system component(s) (Refer to GROUP 16 - Alternator).
Then go to Step 3.
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STEP 3. Measure the resistance at the electric parking brake ECU connector.
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(1)Disconnect the connector and measure at the wiring harness side.
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(2)Measure the resistance between GND1 terminal and body earth.
OK: Continuity exists (2 Ω or less).
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(3)Measure the resistance between GND2 terminal and body earth.
OK: Continuity exists (2 Ω or less).
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Q.
Is the check result normal?
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Go to Step 4.
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The earth circuit may be open. Repair the wiring harness wires or connectors between
the electric parking brake ECU connector and the body earth.
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STEP 4. Measure the voltage at the electric parking brake ECU connector.
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(1)Disconnect the electric parking brake ECU connector and measure at the wiring harness
side.
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(2)Measure the voltage between the +ECU terminal and body earth.
OK: Battery voltage
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Q.
Is the check result normal?
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Go to Step 5.
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The power supply circuit may be open. Repair the wiring harness wires or connectors
between the electric parking brake ECU connector and the fusible link.
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STEP 5. Check whether the diagnosis code is set again.
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Check again if the diagnosis code is set.
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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)Operate the electric parking brake switch to apply and then release the electric
parking brake.
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(5)Check if the diagnosis code is set.
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Q.
Is diagnosis code No. C1861 set?
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Replace the electric parking brake ECU (Refer to  ).
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The trouble can be an intermittent malfunction (Refer to GROUP 00 - How
to Cope with Intermittent Malfunction).
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