Introduction:
The B1806 trouble code indicates a fault within the lamp tail output circuit of a vehicle's control system, often associated with the Body Control Module (BCM) or a similar electronic module. This circuit is responsible for supplying power to the tail lights, ensuring they illuminate properly for visibility and safety. A B1806 code can result in non-functional tail lights, potentially leading to safety hazards and legal issues. Diagnosing and resolving this issue promptly is crucial.
Understanding the B1806 Code: A Comprehensive Overview
| Category | Description | Potential Causes |
|---|---|---|
| Code Definition | Indicates a malfunction in the circuit that provides power to the tail lights (lamp tail output). Specifically, the voltage or current is outside the expected range. | Shorted or open wiring in the tail light circuit, faulty tail light bulbs, corroded connectors, malfunctioning Body Control Module (BCM) or related module, blown fuses or relays, and electrical interference. |
| Symptoms | Tail lights not working, tail lights dim or flickering, other lights malfunctioning (e.g., brake lights, turn signals), warning lights on the dashboard (e.g., check engine light), BCM-related issues. | |
| Diagnostic Steps | Visual inspection of wiring and connectors, checking fuses and relays, testing tail light bulbs, measuring voltage and ground at the tail light socket, using a scan tool to read BCM data, isolating the short or open circuit, testing the BCM output signal, and verifying proper grounding. | |
| Common Solutions | Replacing faulty tail light bulbs, repairing or replacing damaged wiring, cleaning or replacing corroded connectors, replacing blown fuses or relays, reprogramming or replacing the BCM, and addressing grounding issues. | |
| Tools Required | Multimeter, scan tool (OBD-II scanner), wiring diagrams, test light, wire stripper/crimper, soldering iron (optional), and basic hand tools. | |
| Related Codes | B1801, B1802, B1803, B1804, B1805, related to other lighting circuits or BCM functions. | |
| Severity | Moderate to High. Non-functional tail lights pose a significant safety risk, especially at night or in low-visibility conditions. Could result in vehicle accidents. | |
| Affected Components | Tail light bulbs, wiring harness, connectors, fuses, relays, Body Control Module (BCM). | |
| Impact on Vehicle Operation | Primarily affects the visibility of the vehicle to other drivers, especially at night or in low-light conditions. May also affect other lighting functions if the BCM is malfunctioning. | |
| Cost to Repair | Varies greatly depending on the cause. Replacing a bulb or fuse is inexpensive. Repairing wiring or replacing the BCM can be significantly more costly. Labor costs also vary by region and shop. |
Detailed Explanations
Code Definition: The B1806 code is a diagnostic trouble code (DTC) indicating an issue within the lamp tail output circuit. This circuit is specifically responsible for providing the necessary power and control to the vehicle's tail lights. The code is typically triggered when the control module (often the BCM) detects an abnormal voltage or current reading in this circuit, indicating a potential short circuit, open circuit, or other malfunction.
Symptoms: The most obvious symptom of a B1806 code is that the tail lights are not functioning correctly. This can manifest as the tail lights being completely off, dim or flickering, or only working intermittently. Other related symptoms might include other lighting malfunctions, such as issues with the brake lights or turn signals, and the illumination of a warning light on the dashboard, such as the check engine light or a dedicated lighting warning indicator. In some cases, the BCM itself may exhibit other issues if the fault is related to its internal circuitry.
Diagnostic Steps: Diagnosing a B1806 code requires a systematic approach. Start with a visual inspection of the tail light assemblies, wiring, and connectors for any obvious signs of damage, corrosion, or loose connections. Next, check the fuses and relays associated with the tail light circuit. A blown fuse or a faulty relay is a common cause. Test the tail light bulbs themselves to ensure they are not burned out. Use a multimeter to measure the voltage and ground at the tail light socket. This will help determine if the circuit is receiving power and has a proper ground connection. A scan tool (OBD-II scanner) can be used to read data from the BCM and other modules, which may provide additional clues about the nature of the fault. If a short circuit or open circuit is suspected, use a wiring diagram to isolate the fault by systematically testing different sections of the wiring harness. Finally, test the BCM output signal to verify that it is sending the correct signal to the tail light circuit.
Common Solutions: The appropriate solution for a B1806 code depends on the underlying cause. Replacing faulty tail light bulbs is a simple fix if the bulbs are burned out. Repairing or replacing damaged wiring and cleaning or replacing corroded connectors can resolve issues related to poor electrical connections. Replacing blown fuses or relays is a straightforward solution for circuit overloads. In more complex cases, reprogramming or replacing the BCM may be necessary if the module itself is malfunctioning. Addressing grounding issues by cleaning and tightening ground connections can also resolve certain types of faults.
Tools Required: A multimeter is essential for measuring voltage, current, and resistance in the tail light circuit. A scan tool (OBD-II scanner) is needed to read diagnostic trouble codes and access data from the BCM. Wiring diagrams are crucial for tracing the wiring and identifying components in the circuit. A test light can be used to quickly check for power and ground at various points in the circuit. Wire strippers/crimpers are necessary for repairing or replacing wiring. A soldering iron (optional) can be used for making permanent wire connections. Basic hand tools such as screwdrivers, pliers, and wrenches are also required.
Related Codes: The B1806 code is often related to other diagnostic trouble codes that involve lighting circuits or BCM functions. Codes such as B1801, B1802, B1803, B1804, and B1805 might indicate issues with other lighting circuits, such as the brake lights, turn signals, or parking lights. These codes often share similar diagnostic and repair procedures. In some cases, the presence of multiple lighting-related codes may point to a more general problem with the BCM or the vehicle's electrical system.
Severity: The severity of a B1806 code is considered moderate to high. Non-functional tail lights pose a significant safety risk, particularly at night or in low-visibility conditions. Without properly functioning tail lights, other drivers may not be able to see the vehicle, increasing the risk of accidents. Furthermore, operating a vehicle with non-functional tail lights may be illegal in many jurisdictions, resulting in fines or other penalties. It is, therefore, important to address a B1806 code promptly to ensure the safety of the vehicle and its occupants.
Affected Components: The B1806 code directly affects the tail light bulbs, the wiring harness that connects the tail lights to the vehicle's electrical system, the connectors that provide electrical connections between the wiring and the tail lights, the fuses and relays that protect and control the tail light circuit, and the Body Control Module (BCM), which is responsible for controlling the tail lights and other vehicle functions. A failure in any of these components can potentially trigger the B1806 code.
Impact on Vehicle Operation: The primary impact of a B1806 code on vehicle operation is related to visibility. Non-functional tail lights make the vehicle less visible to other drivers, especially in low-light conditions. This can increase the risk of accidents and make it more difficult for other drivers to judge the vehicle's position and speed. In some cases, a malfunctioning BCM can also affect other vehicle functions, such as the interior lighting, power windows, or door locks.
Cost to Repair: The cost to repair a B1806 code can vary significantly depending on the cause of the problem. Replacing a bulb or fuse is a relatively inexpensive repair, typically costing only a few dollars. Repairing damaged wiring or replacing corroded connectors can be more costly, potentially ranging from $50 to $200, depending on the extent of the damage and the labor required. Replacing the BCM is the most expensive repair, as the BCM itself can cost several hundred dollars, and the labor to replace and reprogram it can also be significant. Labor costs also vary depending on the region and the shop.
Frequently Asked Questions
What does the B1806 code mean? It indicates a problem with the circuit that powers your vehicle's tail lights, specifically the output from the Body Control Module (BCM) to those lights.
Can I drive with a B1806 code? Driving with malfunctioning tail lights is unsafe and illegal. Repair the issue as soon as possible.
What are the common causes of a B1806 code? Common causes include faulty bulbs, damaged wiring, corroded connectors, blown fuses, and a malfunctioning BCM.
How do I diagnose a B1806 code? Start with a visual inspection, check fuses and bulbs, and use a multimeter to test the circuit. A scan tool can provide additional information.
How much does it cost to fix a B1806 code? The cost varies depending on the cause, ranging from a few dollars for a bulb to hundreds for a BCM replacement.
Conclusion
The B1806 code signifies a problem in the tail light output circuit, potentially compromising safety and legality. A systematic approach to diagnosis and repair, including visual inspection, circuit testing, and component replacement, is crucial to resolving this issue and restoring proper tail light function.