Introduction
The diagnostic trouble code (DTC) B1695, "Auto Lamp On Circuit Short to Battery," indicates an electrical fault within the automatic headlight system of a vehicle. This code signifies that the control module has detected an unintended voltage supply to the circuit responsible for activating the automatic headlights, potentially leading to their continuous illumination or other system malfunctions. Addressing this issue promptly is crucial to prevent battery drain, component damage, and ensure proper headlight operation for safe driving.
Comprehensive Table of B1695 Fault
| Category | Description | Possible Causes |
|---|---|---|
| Definition | Auto Lamp On Circuit Short to Battery | The automatic headlight activation circuit is receiving unintended voltage from the battery, even when it shouldn't be active. This means the circuit is 'shorted' to the battery voltage. |
| Symptoms | Headlights stay on constantly, even with the ignition off. Battery drain. Malfunctioning automatic headlight function (doesn't turn on/off properly with ambient light). Possible blown fuses related to the headlight or lighting control system. * Error code B1695 present in the vehicle's computer. | Short circuit in the wiring harness: Damaged or chafed wires making contact with a power source. Faulty Auto Light Sensor: The sensor itself may be sending incorrect signals. Defective Headlight Control Module: The module responsible for managing the headlights may be malfunctioning internally. Wiring harness damage: Damage from rodents, accidents, or general wear and tear can expose wires and cause shorts. Corroded Connectors: Corrosion can create unintended electrical paths. Aftermarket modifications: Incorrect installation of aftermarket lighting or electrical accessories can disrupt the factory wiring. * Failed Relay: A stuck or shorted relay in the auto lamp circuit. |
| Diagnostic Steps | Visual Inspection: Carefully examine the wiring harness for any signs of damage, chafing, or corrosion. Check connectors for secure fit and corrosion. Check Fuses: Inspect all fuses related to the headlight and lighting control systems. Replace any blown fuses. Scan the Vehicle's Computer: Use an OBD-II scanner to confirm the presence of the B1695 code and check for any other related codes. Voltage Testing: Use a multimeter to check the voltage at the auto lamp circuit. Compare the readings to the vehicle's wiring diagram. Component Testing: Test the auto light sensor and headlight control module according to the manufacturer's specifications. Wiring Diagram Review: Consult the vehicle's wiring diagram to understand the circuit layout and identify potential short locations. Circuit Isolation: Disconnect components and sections of the wiring harness to isolate the short. Resistance Testing: Use a multimeter to measure the resistance of the wiring harness and components to identify short circuits. | |
| Commonly Affected Components | Headlight Control Module Auto Light Sensor (also known as twilight sensor or ambient light sensor) Wiring Harness (specifically, the wiring between the sensor, module, and headlights) Headlight Relay * Fuses related to the headlight circuit | |
| Severity | High. A short circuit can cause significant battery drain and potentially damage electrical components. Continuously illuminated headlights can also attract unwanted attention and reduce bulb life. | |
| Repair Costs | Varies depending on the cause. Replacing a blown fuse: Relatively inexpensive. Repairing damaged wiring: Moderate cost, depending on the extent of the damage. * Replacing the auto light sensor or headlight control module: Higher cost, due to the price of the parts and labor involved. | |
| Related DTCs | Other headlight-related DTCs, particularly those indicating open circuits or other shorts in the headlight system. Codes related to the Body Control Module (BCM) may also be present. | |
| Tools Required | OBD-II Scanner Multimeter Wiring Diagram for the specific vehicle Wire Strippers Wire Crimpers Electrical Tape * Terminal Test Kit (for testing connectors) |
Detailed Explanations
Definition: Auto Lamp On Circuit Short to Battery
This diagnostic code means that the circuit designed to activate the automatic headlights is receiving power directly from the battery when it shouldn't be. Normally, the headlight control module, based on input from the auto light sensor, controls the flow of electricity to the headlights. A short to battery bypasses this control, forcing the headlights to stay on. This unwanted voltage supply indicates a fault within the electrical system, specifically a short circuit where the headlight activation circuit is directly connected to the battery power.
Symptoms
The most obvious symptom is that the headlights stay on continuously, even when the ignition is off and the ambient light is bright. This constant illumination leads to battery drain, which can prevent the car from starting. The automatic headlight function will also malfunction, failing to turn on or off properly based on ambient light conditions. Blown fuses within the headlight or lighting control circuits are also a common indicator. Finally, the B1695 error code will be stored in the vehicle's computer and can be retrieved using an OBD-II scanner.
Diagnostic Steps
The diagnostic process begins with a visual inspection of the wiring harness, looking for any signs of damage, chafing, or corrosion. Next, check all fuses related to the headlight system and replace any that are blown. Use an OBD-II scanner to confirm the B1695 code and check for any other related codes. A multimeter is essential for voltage testing at the auto lamp circuit, comparing the readings to the vehicle's wiring diagram. The auto light sensor and headlight control module should be tested according to the manufacturer's specifications. Consulting the vehicle's wiring diagram is crucial to understanding the circuit layout and identifying potential short locations. Circuit isolation by disconnecting components and sections of the wiring harness can help pinpoint the short. Finally, resistance testing using a multimeter can help measure the resistance of the wiring harness and components to identify short circuits.
Commonly Affected Components
The Headlight Control Module is a primary suspect as it manages the auto headlight function. The Auto Light Sensor (also known as a twilight sensor or ambient light sensor) can also be faulty, sending incorrect signals. The Wiring Harness, particularly the wiring connecting the sensor, module, and headlights, is a common source of shorts due to damage. The Headlight Relay can become stuck or shorted, and Fuses related to the headlight circuit are often blown due to the short.
Severity
The severity of a B1695 code is considered High. The short circuit causes significant battery drain, potentially leaving you stranded. It can also damage electrical components due to the unintended voltage. Moreover, continuously illuminated headlights attract unwanted attention and shorten the lifespan of the headlight bulbs.
Repair Costs
Repair costs can vary considerably. Replacing a blown fuse is relatively inexpensive. Repairing damaged wiring can be moderately costly, depending on the extent of the damage and the labor involved. Replacing the auto light sensor or headlight control module is the most expensive option, due to the cost of the parts and the labor for diagnosis and replacement.
Related DTCs
Other headlight-related DTCs, particularly those indicating open circuits or other shorts in the headlight system, are often present alongside B1695. Codes related to the Body Control Module (BCM) may also appear, as the BCM often interacts with the headlight control system.
Tools Required
Essential tools include an OBD-II Scanner to read and clear the code, a Multimeter for voltage and resistance testing, and the Wiring Diagram for the specific vehicle. Other helpful tools include Wire Strippers, Wire Crimpers, Electrical Tape, and a Terminal Test Kit for testing connectors.
Frequently Asked Questions
What does the B1695 code mean? The B1695 code indicates that the auto lamp on circuit has a short to battery, meaning it's receiving power when it shouldn't be, causing the headlights to stay on.
Can I drive with a B1695 code? While you can drive, it's not recommended due to the risk of battery drain and potential damage to electrical components. Get it fixed as soon as possible.
How do I fix a B1695 code? Start by inspecting the wiring for damage, checking the fuses, and testing the auto light sensor and headlight control module. Repair or replace any faulty components.
Is a B1695 code serious? Yes, it's a serious issue that can lead to battery drain, damaged electrical components, and potential safety hazards.
Will replacing the auto light sensor fix the B1695 code? It might, but the short could be elsewhere. Thoroughly diagnose the circuit before replacing any parts.
Conclusion
The B1695 code signifies a serious electrical fault in the automatic headlight system, indicating a short to battery. Addressing this issue promptly through careful diagnosis and repair is crucial to prevent battery drain, component damage, and ensure the proper functioning of the headlights for safe driving.