The OBD-II trouble code B1815 – „Wiper Rear Motor Down Relay Coil Circuit Open” points to an issue within your vehicle’s rear windshield wiper system. Specifically, it indicates that the electrical circuit controlling the relay coil responsible for lowering the rear wiper motor is open or interrupted. This fault can lead to improper functioning of the rear wiper, affecting visibility and safety during adverse weather conditions. If you’ve encountered this code, don’t worry—keep scrolling! In this article, you’ll find practical guidance on how to identify the symptoms, understand the common causes, and carry out effective repairs to get your rear wiper back in proper working order.

What symptoms might indicate the B1815 error?

A malfunction in the rear wiper system can significantly affect the vehicle’s ability to maintain clear visibility through the rear window. Drivers may notice several specific symptoms indicating this issue.

  • 1. Rear wiper does not activate: The rear wiper fails to start when switched on.
  • 2. Intermittent rear wiper operation: The rear wiper works sporadically or stops suddenly.
  • 3. No response from rear wiper controls: The control switch for the rear wiper does not produce any action.
  • 4. Unusual clicking noises: Clicking sounds occur behind the rear hatch, indicating relay issues.
  • 5. Rear wiper stuck in one position: The wiper blade remains stationary and does not move across the window.

      • Common reasons that can lead to error code B1815

      There are several common technical issues that can lead to this error code. Identifying these problems is essential for effective troubleshooting and repair.

      • 1. Blown Fuse: A fuse related to the rear wiper motor circuit may have blown, interrupting electrical flow.
      • 2. Damaged Relay: The relay responsible for controlling the rear wiper motor may be faulty or damaged.
      • 3. Broken Wiring: Wiring in the relay coil circuit could be broken or disconnected, causing an open circuit.
      • 4. Corroded Connectors: Corrosion at connector terminals can prevent proper electrical contact and signal transmission.
      • 5. Faulty Rear Wiper Motor: The motor itself might have an internal fault affecting the relay coil circuit operation.

      B1815 at-home error code check step by step

      Diagnosing the B1815 – Wiper Rear Motor Down Relay Coil Circuit Open issue at home is entirely feasible with some basic tools and a systematic approach. By using your own equipment and an OBD-II scanner, you can efficiently pinpoint whether the relay coil circuit is faulty without needing professional diagnostics.

      First, connect your OBD-II scanner to the vehicle’s diagnostic port and access live data related to the rear wiper motor relay operation. Next, with the ignition on but engine off, use a multimeter to check for voltage continuity at the relay coil terminals; lack of voltage or an open circuit indicates a coil failure. Additionally, inspect the relay socket and wiring harness for signs of corrosion or damage that could interrupt the circuit. Finally, if available, swap the suspect relay with a known good one of identical specifications to confirm if the fault clears, verifying whether the relay coil circuit is indeed open or defective.

      B1815 error repair at home: What can you do yourself and when do you need a mechanic?

      • 1. Relay Connector Inspection: Check the rear wiper motor relay connector for any loose or corroded terminals and clean or secure them as needed.
      • 2. Fuse Check and Replacement: Locate the fuse related to the rear wiper motor circuit, inspect it for damage or burnout, and replace it if necessary.
      • 3. Wiring Continuity Test: Use a multimeter to test the wiring between the relay and the rear wiper motor for any breaks or shorts, repairing damaged wires with appropriate connectors or tape.
      • 4. When to Seek Professional Help: If the above steps do not resolve the issue, or if you are uncomfortable handling electrical components, it is advisable to consult a certified technician for advanced diagnostics and repair.

      Consequences of error B1815 if you don’t fix it in time

      Ignoring this issue can lead to several significant long-term consequences that affect both safety and vehicle functionality. Addressing these outcomes promptly is crucial to avoid further complications.

      • 1. Reduced Visibility: Impaired rear wiper operation decreases rear window clarity during adverse weather, compromising driver visibility.
      • 2. Increased Accident Risk: Poor visibility heightens the likelihood of collisions, especially in rain or snow conditions.
      • 3. Electrical System Damage: Prolonged circuit issues may cause further electrical faults, potentially damaging related components.
      • 4. Higher Repair Costs: Delaying repairs can escalate the problem, leading to more extensive and expensive fixes.
      • 5. Vehicle Inspection Failure: Malfunctioning wipers can cause the vehicle to fail safety inspections or roadworthiness tests.
      • 6. Decreased Resale Value: Persistent unresolved faults reduce the overall value and marketability of the vehicle.

          • Here’s how to prevent the B1815 error with a few simple steps

          Wiper system errors can lead to inconvenient and unsafe driving conditions. Implementing preventive measures helps maintain optimal functionality and avoid such faults.