Introduction
The B1819 diagnostic trouble code (DTC) indicates a problem within the rear wiper motor control circuit, specifically related to the "Up" relay coil. This code signals that the vehicle's computer, typically the body control module (BCM), has detected an open circuit in the coil of the relay responsible for powering the rear wiper motor in the upward direction. Understanding the B1819 code is crucial for diagnosing and repairing rear wiper malfunctions, ensuring optimal visibility and safety during inclement weather.
Comprehensive Table: B1819 Wiper Rear Motor Up Relay Coil Circuit Open
| Topic | Description | Possible Causes |
|---|---|---|
| B1819 Code Definition | Indicates an open circuit in the rear wiper motor "Up" relay coil circuit. The BCM isn't seeing the expected electrical continuity through the relay coil, preventing it from activating the wiper motor to move upwards. | Open circuit in the relay coil itself, wiring harness damage (broken wires, corroded connectors), faulty relay, faulty BCM, blown fuse, poor ground connection, corrosion on relay terminals. |
| Rear Wiper Motor "Up" Relay | A small electromagnetic switch that controls the power supply to the rear wiper motor. When the BCM sends a signal, the relay coil energizes, creating a magnetic field that closes the switch and allows power to flow to the motor, causing the wiper to move upwards (or in the defined "up" direction). | Defective relay, corrosion on relay terminals, relay coil failure (open circuit), improper relay installation. |
| Body Control Module (BCM) | The electronic control unit that manages various body functions, including the rear wiper system. It receives input from the wiper switch and other sensors and sends signals to the rear wiper motor relay to control its operation. | Faulty BCM (rare), corrupted BCM software, BCM not receiving the correct signals from the wiper switch, BCM internal failure related to the rear wiper circuit. |
| Wiring Harness & Connectors | The network of wires and connectors that connect the BCM, relay, wiper motor, and power supply. | Broken wires, corroded connectors, loose connections, damaged wiring insulation, chafing against metal surfaces, water intrusion into connectors. Specifically, focus on the wiring between the BCM and the relay, and the relay and the wiper motor. |
| Ground Connection | The point where the electrical circuit is connected to the vehicle's chassis, providing a return path for the current. A good ground is essential for proper circuit operation. | Loose ground connection, corroded ground connection, paint or rust interfering with the ground connection. The ground connection for the BCM and the rear wiper system should be inspected. |
| Fuse | A safety device that protects the electrical circuit from overcurrent. If the current exceeds a certain level, the fuse will blow, interrupting the circuit. | Blown fuse (due to short circuit or overload), incorrect fuse rating, intermittent short circuit causing the fuse to blow repeatedly. Check the fuse specifically designated for the rear wiper system. |
| Symptoms | Observable issues indicating a problem with the rear wiper system. | Rear wiper not working at all, rear wiper working intermittently, rear wiper moving in only one direction (down, but not up), B1819 code present, other related DTCs present (e.g., related to the wiper switch). |
| Diagnostic Tools | Equipment used to diagnose the problem. | Scan tool (to read DTCs), multimeter (to test voltage, continuity, and resistance), wiring diagram (to trace the circuit), test light (to check for power), relay tester (to test the relay), terminal cleaning tools. |
| Repair Procedures | Steps taken to fix the problem. | Inspect and repair wiring harness and connectors, replace faulty relay, replace blown fuse, repair or replace faulty ground connection, diagnose and repair or replace faulty BCM (last resort), test and replace faulty wiper motor (if the motor itself is the cause of the short), clear DTCs and retest. |
| Voltage Measurement | Using a multimeter to check the voltage at various points in the circuit. | Measure voltage at the relay coil (with the wiper switch activated), at the BCM output for the relay, and at the power supply to the relay. A lack of voltage indicates an open circuit or a power supply problem. |
| Continuity Testing | Using a multimeter to check for a complete electrical path between two points in the circuit. | Test continuity of the wiring between the BCM and the relay, between the relay and the wiper motor, and of the relay coil itself. An open circuit indicates a break in the wiring or a faulty component. |
| Resistance Measurement | Using a multimeter to measure the resistance of a component or circuit. | Measure the resistance of the relay coil. A very high or infinite resistance indicates an open circuit in the coil. |
Detailed Explanations
B1819 Code Definition: The B1819 code specifically pinpoints an open circuit within the relay coil that controls the upward movement of the rear wiper motor. This means the BCM is trying to activate the relay, but it's not detecting the expected electrical current flow through the relay coil. This typically prevents the relay from energizing and powering the wiper motor in the "up" direction.
Rear Wiper Motor "Up" Relay: This relay acts as an intermediary between the BCM and the rear wiper motor. The BCM sends a small electrical signal to the relay coil. When the coil is energized, it creates a magnetic field that pulls a switch closed. This closed switch then allows a larger current to flow from the power supply to the rear wiper motor, causing it to operate. A faulty relay, particularly an open coil, will prevent the wiper motor from functioning correctly.
Body Control Module (BCM): The BCM is the central control unit for many of the vehicle's electronic accessories. In the case of the rear wiper, it monitors the wiper switch position and other inputs, and then sends the appropriate signals to the rear wiper motor relay to control its operation. While a BCM failure is less common, it's essential to consider it as a potential cause if other troubleshooting steps don't resolve the issue.
Wiring Harness & Connectors: The wiring harness and connectors are the pathways that carry electrical signals between the various components of the rear wiper system. Damage to these wires or connectors, such as breaks, corrosion, or loose connections, can disrupt the circuit and trigger the B1819 code. Thoroughly inspect the wiring and connectors, especially in areas prone to moisture or physical stress.
Ground Connection: A solid ground connection is crucial for the proper functioning of any electrical circuit. A poor ground connection can cause erratic behavior, voltage drops, and incorrect readings, all of which can lead to diagnostic trouble codes like B1819. Ensure that the ground connections for the BCM and the rear wiper system are clean, tight, and free of corrosion.
Fuse: Fuses are designed to protect electrical circuits from overcurrent. A blown fuse in the rear wiper circuit can interrupt the power supply to the relay or wiper motor, preventing them from operating. Always check the fuse first when troubleshooting electrical issues. Replace the fuse with one of the correct amperage rating. If the fuse blows repeatedly, it indicates a short circuit that needs to be located and repaired.
Symptoms: The most obvious symptom of a B1819 code is a rear wiper that doesn't work, or only works intermittently. In some cases, the wiper might only work in one direction (e.g., down, but not up). The presence of the B1819 code itself is a key symptom. Other related DTCs might also be present, providing further clues to the underlying problem.
Diagnostic Tools: Using the right tools is essential for accurate diagnosis. A scan tool is needed to read the B1819 code and any other related DTCs. A multimeter is used to test voltage, continuity, and resistance in the circuit. A wiring diagram is invaluable for tracing the circuit and identifying the location of components. A test light can quickly check for power at various points in the circuit. A relay tester can be used to specifically test the functionality of the relay.
Repair Procedures: The repair procedure will depend on the root cause of the problem. Start by inspecting the wiring harness and connectors for any signs of damage. Replace any faulty components, such as the relay or fuse. Repair any damaged wiring or connectors. Ensure that all ground connections are clean and tight. If all other troubleshooting steps fail, the BCM might need to be diagnosed and potentially replaced.
Voltage Measurement: Voltage measurements can help pinpoint the location of an open circuit or a power supply problem. Check the voltage at the relay coil, the BCM output for the relay, and the power supply to the relay. A lack of voltage at any of these points indicates a problem in that section of the circuit. For example, if you have voltage at the BCM output but not at the relay coil, there's likely an open circuit in the wiring between the BCM and the relay.
Continuity Testing: Continuity testing verifies that there's a complete electrical path between two points in the circuit. Use a multimeter to check the continuity of the wiring between the BCM and the relay, between the relay and the wiper motor, and of the relay coil itself. An open circuit indicates a break in the wiring or a faulty component. Disconnect the power source before performing continuity tests to avoid damaging the multimeter or the vehicle's electrical system.
Resistance Measurement: Measuring the resistance of the relay coil can help determine if the coil is open. A normal relay coil will have a measurable resistance. A very high or infinite resistance indicates an open circuit within the coil, confirming that the relay is faulty.
Frequently Asked Questions
What does the B1819 code mean? The B1819 code indicates an open circuit in the rear wiper motor "Up" relay coil circuit. This means the vehicle's computer isn't seeing the expected electrical continuity through the relay coil.
What are the common causes of the B1819 code? Common causes include a faulty relay, damaged wiring, corroded connectors, or a blown fuse. Less frequently, it could indicate a problem with the body control module (BCM).
How do I fix the B1819 code? Start by inspecting the wiring and connectors, then test the relay and fuse. Repair or replace any faulty components. If the problem persists, further diagnosis of the BCM might be necessary.
Can a bad relay cause the B1819 code? Yes, a faulty relay with an open coil is one of the most common causes of the B1819 code. The open coil prevents the relay from energizing and powering the wiper motor.
Is the B1819 code serious? While the rear wiper might not be essential for driving, it's important for visibility in inclement weather. Addressing the B1819 code is recommended for safety.
Conclusion
The B1819 code signifies an open circuit in the rear wiper motor "Up" relay coil circuit, preventing the rear wiper from functioning correctly. A systematic approach to diagnosis, including inspecting wiring, testing components, and using diagnostic tools, is essential for identifying and resolving the underlying cause. Always prioritize safety and consult a qualified technician if you're not comfortable performing the repairs yourself.