The B1690 diagnostic trouble code (DTC) indicates an issue within the auto lamp delay circuit. This circuit is responsible for keeping the headlights illuminated for a brief period after the ignition is turned off, providing visibility for the driver to safely exit the vehicle. A "circuit open" signifies a break in the electrical pathway, preventing the system from functioning correctly. This article will delve into the causes, symptoms, diagnosis, and repair of the B1690 code, providing a comprehensive understanding of this automotive issue.
| Component/Aspect | Description | Potential Causes |
|---|---|---|
| Auto Lamp Delay System | A system that keeps the headlights on for a short period after the ignition is switched off, providing illumination for the driver to exit the vehicle safely. | Faulty auto lamp delay relay, damaged wiring harness, corroded connectors, defective light sensor, faulty BCM (Body Control Module), open circuit in the wiring, short circuit to ground, short circuit to voltage. |
| B1690 DTC | Diagnostic Trouble Code indicating an open circuit within the auto lamp delay system. This means the electrical circuit is broken, preventing current flow. | Broken wire in the auto lamp delay circuit, corroded or loose connectors, faulty relay, defective light sensor, internal failure within the BCM. |
| Symptoms | Observable malfunctions resulting from the B1690 code. | Headlights do not stay on after ignition is turned off, headlights stay on continuously, delayed headlight function is intermittent, other electrical issues (related to BCM function), DTC B1690 stored in the vehicle's computer. |
| Diagnostic Tools | Tools used to diagnose the B1690 code and the underlying issue. | OBD-II scanner, multimeter, wiring diagram, test light. |
| Troubleshooting Steps | A systematic approach to identifying the root cause of the B1690 code. | Visual inspection of wiring and connectors, check for voltage and ground at the auto lamp delay relay, testing the light sensor, checking the BCM for proper operation, using a multimeter to check circuit continuity. |
| Repair Procedures | Actions taken to fix the issue causing the B1690 code. | Repairing or replacing damaged wiring, cleaning or replacing corroded connectors, replacing the auto lamp delay relay, replacing the light sensor, reprogramming or replacing the BCM (in rare cases). |
| Related DTCs | Other Diagnostic Trouble Codes that may be present alongside B1690. | Any DTC related to the BCM, headlight circuit, or lighting system in general. Common examples include codes related to headlight high/low beam circuits, parking light circuits, and other body control functions. |
| Impact on Vehicle Operation | Consequences of ignoring the B1690 code. | Inconvenience of non-functioning auto lamp delay feature, potential safety hazard in dark environments, potential battery drain if headlights remain on continuously (though this is less likely with an open circuit), potential for misdiagnosis of other electrical issues. |
| Component Locations | Common locations of components within the auto lamp delay system. | Auto Lamp Delay Relay: Typically located in the under-hood fuse box or a relay center under the dashboard. Consult vehicle-specific repair information. Light Sensor: Usually located on the dashboard, near the windshield. BCM: Typically located under the dashboard, often near the steering column or in the center console. Location is highly vehicle-specific. |
| Wiring Diagram Usage | Importance of using a wiring diagram during diagnosis. | A wiring diagram is essential for tracing the auto lamp delay circuit, identifying components, and pinpointing the location of the open circuit. It shows the connections between the various components and allows for accurate testing. |
| BCM Programming | Necessity of programming after BCM replacement. | If the BCM is replaced, it often requires programming to match the vehicle's specific configuration and options. Failure to program the BCM can result in various malfunctions. |
Detailed Explanations
Auto Lamp Delay System: This system enhances driver safety and convenience by providing illumination for a short period after the vehicle is turned off. This allows the driver to see their surroundings while exiting the car, especially in dark environments. The system typically uses a light sensor to detect ambient light levels and a timer to control the duration of the delay.
B1690 DTC: The B1690 code specifically indicates an open circuit in the auto lamp delay system. An open circuit means there is a break in the electrical path, preventing the flow of current. This can be caused by a broken wire, a loose connection, or a faulty component.
Symptoms: The most obvious symptom is the malfunction of the auto lamp delay feature. This could manifest as the headlights not staying on at all after the ignition is switched off, or in rare cases (if the open circuit is intermittent and causing erratic behavior), the headlights might stay on continuously. Other symptoms could include intermittent operation of the delay function or other electrical issues related to the BCM.
Diagnostic Tools: An OBD-II scanner is used to retrieve the B1690 code from the vehicle's computer. A multimeter is crucial for testing voltage, ground, and continuity within the circuit. A wiring diagram is essential for tracing the circuit and identifying the location of components. A test light can also be used to quickly check for power and ground.
Troubleshooting Steps: The first step is a visual inspection of the wiring and connectors in the auto lamp delay circuit. Look for any signs of damage, corrosion, or loose connections. Next, use a multimeter to check for voltage and ground at the auto lamp delay relay. Test the light sensor to ensure it is functioning correctly. If all other components check out, the BCM may be the cause.
Repair Procedures: Repairing or replacing damaged wiring is a common repair. Cleaning or replacing corroded connectors is also important. Replacing the auto lamp delay relay or light sensor may be necessary if they are found to be faulty. In rare cases, the BCM may need to be reprogrammed or replaced.
Related DTCs: The presence of other DTCs related to the BCM, headlight circuit, or lighting system can provide valuable clues to the underlying issue. For example, codes related to headlight high/low beam circuits, parking light circuits, or other body control functions may indicate a more widespread problem with the BCM or the vehicle's electrical system.
Impact on Vehicle Operation: While the auto lamp delay feature is primarily a convenience feature, its malfunction can be a safety concern in dark environments. The B1690 code itself doesn't directly affect the engine or transmission, but it can lead to misdiagnosis of other electrical issues if not properly addressed. A continuously illuminated headlight (though less likely with an open circuit) could also drain the battery.
Component Locations: Finding the components requires consulting the vehicle's service manual. The auto lamp delay relay is typically located in the under-hood fuse box or a relay center under the dashboard. The light sensor is usually located on the dashboard, near the windshield. The BCM is typically located under the dashboard, often near the steering column or in the center console.
Wiring Diagram Usage: A wiring diagram is indispensable for diagnosing the B1690 code. It provides a detailed map of the auto lamp delay circuit, showing the location of components, wire colors, and connection points. This allows for accurate tracing of the circuit and pinpointing the location of the open circuit.
BCM Programming: When replacing the BCM, it's often crucial to program it to match the vehicle's specific configuration and options. This programming ensures that all of the vehicle's systems function correctly. Failure to program the BCM can result in various malfunctions, including issues with the auto lamp delay system.
Frequently Asked Questions
What does the B1690 code mean? The B1690 code indicates an open circuit in the auto lamp delay system, meaning there is a break in the electrical pathway.
What are the symptoms of a B1690 code? The primary symptom is the auto lamp delay feature not working, either by not turning on or (less likely) staying on continuously.
Can I fix the B1690 code myself? Depending on your mechanical skills, you might be able to fix it by checking wiring and replacing faulty components, but professional diagnosis is recommended for complex issues.
What tools do I need to diagnose a B1690 code? You'll need an OBD-II scanner, a multimeter, and a wiring diagram for your specific vehicle.
How important is the auto lamp delay feature? While primarily a convenience feature, it enhances safety by providing illumination when exiting the vehicle in dark environments.
Conclusion
The B1690 code signifies an open circuit within the auto lamp delay system, leading to the malfunction of this convenience feature. Thorough diagnosis using appropriate tools and a wiring diagram is crucial for pinpointing the root cause, which often involves repairing damaged wiring, replacing faulty components, or, in rare cases, addressing issues with the BCM. Prompt attention to this code ensures the proper functioning of the auto lamp delay system and avoids potential misdiagnosis of other electrical problems.