Introduction: The B1807 code, indicating a "Lamp Tail Output Circuit Open," is a diagnostic trouble code (DTC) that signals a problem within the electrical circuit controlling the tail lights of a vehicle. This code is commonly associated with various vehicle makes and models, and its presence often points to a malfunction that needs immediate attention. Addressing this issue promptly is crucial for ensuring road safety and preventing potential accidents.
Table: B1807 Lamp Tail Output Circuit Open - Details & Troubleshooting
| Topic | Description | Common Causes |
|---|---|---|
| Definition | The B1807 code signifies that the vehicle's electronic control unit (ECU) has detected an open circuit in the tail light output circuit. This means that the electrical connection between the ECU and the tail lights is broken, preventing the lights from functioning correctly. The "tail output circuit" refers to the wiring, connectors, and control module components that deliver power to the tail lights when they are supposed to be illuminated (e.g., when headlights are on or brakes are applied). | Blown Tail Light Bulb: The most frequent cause. A burnt-out filament breaks the circuit. Faulty Wiring: Damaged, corroded, or broken wires in the tail light circuit. Loose or Corroded Connectors: Poor connections due to corrosion or looseness interrupt the electrical flow. Defective Tail Light Assembly: Internal damage to the tail light housing or circuit board within the assembly. Faulty Body Control Module (BCM): Less common, but the BCM, which controls various electrical functions, can malfunction. Open Circuit in the Wiring Harness: A break anywhere in the wiring harness leading to the tail lights. Short to Ground: Although the code specifies an "open" circuit, related shorts can sometimes trigger similar error codes due to abnormal voltage readings. Aftermarket Accessories: Incorrectly installed aftermarket lights or modifications can disrupt the factory wiring. |
| Symptoms | The most obvious symptom is that one or more tail lights fail to illuminate when they should. Other symptoms can include: Dim Tail Lights: The tail lights may be very dim or flicker. Intermittent Tail Light Operation: The lights may work sometimes but not others. Other Lighting Issues: Related problems, such as brake lights not functioning correctly, or other lighting malfunctions, may also occur. Dashboard Warning Light: Illumination of the check engine light or a dedicated lighting warning light on the dashboard. * Vehicle Fails Inspection: Failure to pass a vehicle safety inspection due to malfunctioning tail lights. | Same as above, in addition to: Recent Vehicle Accident: Damage to the tail light assembly or wiring. Exposure to Harsh Weather: Corrosion due to water and salt. Rodent Damage: Wires chewed by rodents. |
| Diagnostic Procedures | A systematic approach is crucial for diagnosing the B1807 code. This involves using a multimeter to test for voltage and continuity in the tail light circuit. Scan tools can also be used to read the code and monitor circuit parameters. Visual inspection of wiring, connectors, and tail light assemblies is essential. Here's a typical diagnostic sequence: 1. Visual Inspection: Check the tail light bulbs for obvious damage. Inspect wiring and connectors for corrosion, damage, or loose connections. 2. Bulb Test: Replace the tail light bulb with a known good bulb. If the problem is resolved, the old bulb was the culprit. 3. Continuity Test: Use a multimeter to check for continuity in the tail light circuit. This will help identify any open circuits. 4. Voltage Test: Use a multimeter to check for voltage at the tail light connector when the lights should be on. 5. Wiring Harness Inspection: Carefully inspect the wiring harness for any signs of damage, such as cuts, frayed wires, or corrosion. 6. Connector Inspection: Check the connectors for corrosion, bent pins, or loose connections. Clean or replace as necessary. 7. BCM Testing: If all other components check out, the BCM may be faulty. This requires specialized testing equipment and may require professional assistance. | Lack of proper tools: Multimeter, scan tool, wiring diagrams. Incorrect testing procedures: Failing to follow the correct sequence or misinterpreting test results. * Intermittent Faults: The problem may only occur under certain conditions, making it difficult to diagnose. |
| Troubleshooting Steps | Check the Tail Light Bulbs: Replace any blown bulbs with the correct type. Inspect and Repair Wiring: Repair any damaged or corroded wiring. Use proper wiring connectors and ensure a secure connection. Clean or Replace Connectors: Clean corroded connectors with electrical contact cleaner. Replace any damaged connectors. Test the Tail Light Assembly: Use a multimeter to test the tail light assembly for continuity and voltage. Replace the assembly if it is faulty. Check the BCM: If all other components check out, the BCM may be faulty. This requires specialized testing equipment and may require professional assistance. Consult Wiring Diagrams: Use wiring diagrams to trace the tail light circuit and identify any potential problems. Isolate the Fault: Systematically disconnect components in the circuit to isolate the fault. Professional Assistance: If you are not comfortable working with electrical systems, seek professional assistance from a qualified mechanic. | Lack of experience: Working with electrical systems can be dangerous if you are not experienced. Incorrect repairs: Improperly repaired wiring or connectors can cause further problems. * Misdiagnosis: Incorrectly identifying the cause of the problem can lead to unnecessary repairs. |
| Potential Solutions | The solution depends on the root cause of the problem. This may involve replacing a blown bulb, repairing damaged wiring, cleaning or replacing corroded connectors, replacing a faulty tail light assembly, or replacing the BCM. In some cases, a simple reset of the ECU may resolve the issue. Replacing Blown Bulbs: A simple and often effective solution. Wiring Repair: Splicing and insulating damaged wires. Connector Cleaning or Replacement: Removing corrosion and ensuring a secure connection. Tail Light Assembly Replacement: Replacing a damaged or malfunctioning assembly. BCM Replacement or Reprogramming: A more complex solution requiring professional assistance. Software Update: In some cases, a software update to the BCM may resolve the issue. | Using incorrect parts: Using the wrong type of bulb or connector. Poor workmanship: Improperly repaired wiring or connectors. * Ignoring underlying issues: Failing to address the root cause of the problem, such as corrosion. |
| Related Codes | Other diagnostic trouble codes that may be related to the B1807 code include: B1806: Lamp Tail Output Circuit Short to Ground. B1808: Lamp Tail Output Circuit High. B1809: Lamp Tail Output Circuit Low. Specific Tail Light Codes: Codes that identify which specific tail light (left or right) is affected. * Other Lighting Codes: Codes related to other lighting systems, such as brake lights, turn signals, or headlights. These codes can help narrow down the source of the problem. | Incorrect interpretation: Misinterpreting the meaning of related codes. Ignoring other symptoms: Failing to consider other symptoms that may be related to the problem. |
Detailed Explanations
Definition: The B1807 code specifically indicates an open circuit in the tail light output circuit. An open circuit means the electrical path is incomplete, preventing current from flowing to the tail lights. The ECU monitors the voltage in the circuit and detects the absence of current flow when the tail lights should be illuminated. This is a critical safety issue, as tail lights are essential for visibility, especially at night or in adverse weather conditions.
Symptoms: The most noticeable symptom is the failure of one or more tail lights to illuminate. This can be a constant failure or an intermittent issue. Dim tail lights, flickering, and other related lighting problems can also occur. The dashboard warning light, often a check engine light or a dedicated lighting indicator, will usually illuminate to alert the driver to the problem. A vehicle failing a safety inspection due to malfunctioning tail lights is another indication.
Diagnostic Procedures: A systematic approach is crucial. Begin with a visual inspection of the bulbs, wiring, and connectors. Use a multimeter to perform continuity and voltage tests. A scan tool can read the code and provide additional information about the circuit. Refer to wiring diagrams to trace the circuit and identify potential problem areas. The goal is to isolate the open circuit and identify the faulty component.
Troubleshooting Steps: Start with the simplest and most common causes, such as checking and replacing the tail light bulbs. Inspect and repair any damaged wiring or corroded connectors. Test the tail light assembly for continuity and voltage. If the problem persists, the BCM may be faulty, requiring professional diagnosis and repair. Consulting wiring diagrams and systematically isolating the fault are essential steps.
Potential Solutions: The solution depends on the root cause. Replacing blown bulbs, repairing damaged wiring, cleaning or replacing corroded connectors, replacing a faulty tail light assembly, or replacing the BCM are all potential solutions. In some cases, a software update to the BCM may resolve the issue. The key is to accurately diagnose the problem and implement the appropriate solution.
Related Codes: Understanding related codes can provide valuable clues. Codes like B1806 (Short to Ground), B1808 (Circuit High), and B1809 (Circuit Low) can indicate different types of electrical problems within the tail light circuit. Specific tail light codes can identify which side (left or right) is affected. Other lighting codes can point to related issues that may be contributing to the problem.
Frequently Asked Questions
What does the B1807 code mean? The B1807 code indicates that the vehicle's computer has detected an open circuit in the tail light output circuit, meaning the electrical connection to the tail lights is broken.
Can I drive with a B1807 code? Driving with a B1807 code is not recommended, as it means your tail lights may not be functioning correctly, posing a safety risk.
How do I fix a B1807 code? Fixing a B1807 code involves diagnosing the cause of the open circuit, which could be a blown bulb, damaged wiring, corroded connectors, or a faulty BCM, and then repairing or replacing the faulty component.
Is the B1807 code a serious problem? Yes, the B1807 code is a serious problem because it affects the functionality of your tail lights, which are crucial for visibility and safety, especially at night.
Do I need a mechanic to fix a B1807 code? While some repairs, like replacing a bulb, can be done yourself, diagnosing and repairing more complex issues, such as wiring problems or a faulty BCM, may require a mechanic.
Can a blown fuse cause a B1807 code? While not directly related to an "open" circuit, a blown fuse in the tail light circuit could lead to similar symptoms and should be checked during the diagnostic process. However, a blown fuse typically indicates a short circuit, which would likely trigger a different code (like a short to ground).
What tools do I need to diagnose a B1807 code? You will need a multimeter, a scan tool (optional but helpful), wiring diagrams for your vehicle, and basic hand tools.
Can aftermarket lights cause a B1807 code? Yes, incorrectly installed or incompatible aftermarket lights can disrupt the factory wiring and trigger a B1807 code.
How much does it cost to fix a B1807 code? The cost to fix a B1807 code can vary widely depending on the cause, ranging from a few dollars for a bulb replacement to hundreds of dollars for wiring repairs or BCM replacement.
Conclusion
The B1807 code, indicating a "Lamp Tail Output Circuit Open," is a serious issue that should be addressed promptly to ensure road safety. Thorough diagnosis, utilizing the information provided above, is essential for identifying the root cause and implementing the appropriate solution.