B1815 – OBD-II DTC

OBD-II DTC B1815 – Wiper Rear Motor Down Relay Coil Circuit Open

DTC B1815 meaning

DTC B1815 refers to a diagnostic trouble code indicating an issue with the rear wiper motor down relay coil circuit. This code is triggered when the vehicle’s onboard diagnostic system detects an open circuit in the relay coil that controls the rear wiper motor’s downward operation. The rear wiper is essential for maintaining visibility during inclement weather, and any malfunction can affect the driver’s ability to see clearly through the rear window.

DTC B1815 symptoms

Common symptoms associated with DTC B1815 may include:

• Rear wiper not functioning when activated.
• Intermittent operation of the rear wiper.
• Rear wiper motor making unusual noises.
• Dashboard warning lights illuminated.

DTC B1815 causes

Several factors can lead to the triggering of DTC B1815, including:

• Faulty rear wiper motor relay.
• Open or damaged wiring in the relay coil circuit.
• Corroded or loose electrical connections.
• Defective rear wiper motor.
• Issues with the vehicle’s body control module (BCM).

DTC B1815 seriousness

The seriousness of DTC B1815 can vary based on the vehicle’s usage and the environmental conditions. While it may not pose an immediate safety risk, a malfunctioning rear wiper can significantly impair visibility during rain or snow, increasing the risk of accidents. It is advisable to address this issue promptly to ensure safe driving conditions.

How to diagnose DTC B1815

To diagnose DTC B1815, follow these steps:

1. Use an OBD-II scanner to confirm the presence of DTC B1815.
2. Inspect the rear wiper motor relay for any visible damage or corrosion.
3. Check the wiring and connectors in the relay coil circuit for continuity and signs of wear.
4. Test the rear wiper motor to ensure it operates correctly when powered directly.
5. Examine the body control module for any faults or programming issues.

How to fix DTC B1815 step-by-step instructions

To fix DTC B1815, follow these step-by-step instructions:

1. Disconnect the vehicle’s battery to ensure safety while working on electrical components.
2. Inspect and replace the rear wiper motor relay if it is found to be faulty.
3. Repair or replace any damaged wiring or connectors in the relay coil circuit.
4. Test the rear wiper motor by connecting it directly to a power source to verify its functionality.
5. Reconnect the battery and clear the DTC using an OBD-II scanner.
6. Test the rear wiper system to ensure it operates correctly.

How to erase DTC B1815

To erase DTC B1815 from the vehicle’s memory, follow these steps:

1. Connect an OBD-II scanner to the vehicle’s diagnostic port.
2. Turn on the vehicle’s ignition 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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