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DTC C1861: Power supply low voltage
 
 
 
 
OPERATION
The electric parking brake ECU is energized from the battery through the fusible links.
 
 
DTC SET CONDITIONS
If the parking brake is not applied or released within a predetermined period due to a low battery voltage, the DTC will be set.
 
 
TROUBLESHOOTING HINTS
  • Battery not charged sufficiently or deteriorated
  • Loose or contaminated battery terminals
  • Open or ground fault in the electric parking brake ECU power supply circuit.
  • Malfunction of the electric parking brake ECU
 
 
DIAGNOSIS
Required Special Tools:
  • MB992006: Extra Fine Probe
STEP 1. Check the battery.
Refer to GROUP 54A - Battery Check , Battery Test .
Is the check result normal?
Go to Step 2.
Charge or replace the battery (Refer to GROUP 54A - Battery ). Then go to Step 3.
 
STEP 2. Check the charging system.
Refer to GROUP 16 - Charging System .
Is the check result normal?
Go to Step 3.
Repair or replace the charging system component(s) (Refer to GROUP 16 - Generator ). Then go to Step 3.
 
STEP 3. Measure the resistance at the electric parking brake ECU connector.
(1) Disconnect the connector and measure at the wiring harness side.
(2) Measure the resistance between GND1 terminal and body ground.
OK: Continuity exists (2 ohms or less).
(3) Measure the resistance between GND2 terminal and body ground.
OK: Continuity exists (2 ohms or less).
Is the check result normal?
Go to Step 4.
The ground circuit may be open. Repair the wiring harness wires or connectors between the electric parking brake ECU connector and the body ground.
 
STEP 4. Measure the voltage at the electric parking brake ECU connector.
(1) Disconnect the electric parking brake ECU connector and measure at the wiring harness side.
(2) Measure the voltage between the +ECU terminal and body ground.
OK: Battery voltage
Is the check result normal?
Go to Step 5.
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.
 
STEP 5. Using scan tool (M.U.T.-IIISE), check whether the DTC is set again.
Check again if the DTC is set.
(1)
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-IIISE).
Connect scan tool (M.U.T.-IIISE). Refer to "How to Connect the Scan Tool (M.U.T.-IIISE) ."
(2) Erase the DTC.
(3) Turn the ignition switch to the LOCK (OFF) position.
(4) Turn the ignition switch to the ON position.
(5) Operate the electric parking brake switch to apply and then release the electric parking brake.
(6) Check the DTC.
Is the DTC C1861 set?
Replace the electric parking brake ECU (Refer to ).
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).