B1820 – OBD-II DTC

OBD-II DTC B1820 – Wiper Rear Motor Up Relay Coil Circuit Short To Battery

DTC B1820 meaning

DTC B1820 refers to a diagnostic trouble code indicating a short circuit in the rear wiper motor up relay coil circuit to the battery. This code is part of the On-Board Diagnostics II (OBD-II) system, which monitors various vehicle components for faults. When the system detects that the rear wiper motor relay coil is receiving an unexpected voltage, it triggers this code to alert the technician of a potential electrical issue.

DTC B1820 symptoms

Common symptoms associated with DTC B1820 may include:

• Rear wiper not functioning
• Intermittent operation of the rear wiper
• Wiper motor running continuously
• Dashboard warning lights illuminated

DTC B1820 causes

Several factors can lead to the triggering of DTC B1820, including:

• Short circuit in the wiring harness
• Faulty rear wiper motor relay
• Defective rear wiper motor
• Corroded or damaged electrical connectors
• Issues with the vehicle’s body control module (BCM)

DTC B1820 seriousness

The seriousness of DTC B1820 can vary. While it may not affect the vehicle’s overall drivability, it can lead to safety concerns if the rear wiper is inoperative during inclement weather. Additionally, ignoring this code may result in further electrical issues or damage to the wiper system.

How to diagnose DTC B1820

To diagnose DTC B1820, follow these steps:

1. Use an OBD-II scanner to confirm the presence of the B1820 code.
2. Inspect the wiring and connectors related to the rear wiper motor and relay for any visible damage or corrosion.
3. Test the rear wiper motor relay for proper operation using a multimeter.
4. Check the voltage at the rear wiper motor while operating the switch to ensure it is receiving the correct voltage.
5. Examine the rear wiper motor for any signs of failure or malfunction.
6. Consult the vehicle’s service manual for specific testing procedures related to the BCM.

How to fix DTC B1820 step-by-step instructions

To fix DTC B1820, follow these steps:

1. Repair or replace any damaged wiring or connectors found during the diagnosis.
2. Replace the faulty rear wiper motor relay if it fails the testing.
3. If the rear wiper motor is defective, replace it with a new unit.
4. Ensure all connections are secure and free of corrosion.
5. Clear the DTC using an OBD-II scanner and test the rear wiper system to confirm proper operation.

How to erase DTC B1820

To erase DTC B1820, follow these steps:

1. Connect an OBD-II scanner to the vehicle’s diagnostic port.
2. Turn the ignition key to the “On” position without starting the engine.
3. Navigate to the “Erase Codes” or “Clear DTCs” option on the scanner.
4. Confirm the action to clear the trouble codes.
5. Disconnect the scanner and start the vehicle to ensure the code does not reappear.

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