The B1373 diagnostic trouble code (DTC) indicates an issue within the illuminated entry system of a vehicle, specifically a short to battery in the illuminated entry relay circuit. This fault can prevent the interior lights from functioning correctly, impacting convenience and potentially safety, especially at night. Understanding the causes, symptoms, and diagnostic procedures is crucial for effective troubleshooting and repair.
| Topic | Description | Possible Causes |
|---|---|---|
| Definition of B1373 | Diagnostic trouble code indicating a short to battery in the illuminated entry relay circuit. This means the relay circuit is receiving unintended power directly from the vehicle's battery. | Short to Battery: A wire in the illuminated entry circuit is making unintended contact with a power source, such as the battery positive terminal or another circuit that is always powered. Faulty Relay: The illuminated entry relay itself has failed internally, causing a short circuit. Damaged Wiring Harness: The wiring harness connected to the illuminated entry relay and associated components has become damaged (e.g., frayed insulation, pinched wires), leading to a short to battery. Corroded Connectors: Corrosion within the connectors of the relay or wiring harness can create a conductive path, resulting in a short circuit. |
| Symptoms | Observable issues resulting from the B1373 code. These can range from non-functional interior lights to battery drain. | Interior Lights Always On: The interior lights remain illuminated even when the doors are closed and the illuminated entry system should be off. Interior Lights Do Not Work: The interior lights fail to activate when the doors are opened or the illuminated entry system is triggered. Battery Drain: The short circuit draws excessive current, leading to a rapid discharge of the vehicle's battery, especially when the vehicle is parked. Blown Fuses: The increased current flow due to the short circuit can cause the fuse protecting the illuminated entry circuit to blow repeatedly. Dim Interior Lights: Reduced brightness in the interior lights can indicate a partial short or voltage drop in the circuit. Relay Clicking/Buzzing: A faulty relay may exhibit unusual clicking or buzzing sounds. |
| Common Vehicle Brands Affected | While B1373 is a generic code, it appears more frequently in certain vehicle brands and models due to specific design or wiring vulnerabilities. | Ford Vehicles: Ford trucks and SUVs (e.g., F-150, Explorer) are commonly reported to experience B1373 codes related to the illuminated entry system. General Motors (GM) Vehicles: GM vehicles like Chevrolet Silverado, GMC Sierra, and Cadillac models may also exhibit this code. * Chrysler/Dodge/Jeep Vehicles: Certain models from these brands may also be susceptible to this issue, though less frequently than Ford and GM. |
| Diagnostic Procedures | Steps to identify and isolate the root cause of the B1373 code. This involves using diagnostic tools and visual inspection. | Visual Inspection: Thoroughly inspect the wiring harness, connectors, and relay associated with the illuminated entry system for any signs of damage, corrosion, or loose connections. Fuse Check: Verify the condition of the fuse protecting the illuminated entry circuit. Replace the fuse if it is blown and observe if it blows again. Relay Testing: Test the illuminated entry relay using a multimeter to check for continuity and resistance. A faulty relay should be replaced. Voltage Testing: Use a multimeter to check for voltage at various points in the illuminated entry circuit. A voltage reading where it should not exist indicates a short to battery. Wiring Harness Testing: Use a multimeter to perform continuity tests and short-to-ground tests on the wiring harness. This will help identify any damaged wires or short circuits. Scan Tool Diagnostics: Use a scan tool to read any other diagnostic trouble codes that may be related to the illuminated entry system. Clear the B1373 code after repairs are completed and retest the system. |
| Troubleshooting Tips | Practical advice for resolving the B1373 code efficiently. This includes specific areas to focus on during the diagnosis. | Focus on Common Problem Areas: Pay close attention to areas where the wiring harness is exposed to vibration, heat, or moisture, as these are common locations for shorts to occur. Check Door Jamb Switches: Inspect the door jamb switches that activate the interior lights when the doors are opened. A faulty switch can sometimes cause the illuminated entry system to malfunction. Use Wiring Diagrams: Consult the vehicle's wiring diagrams to understand the layout of the illuminated entry circuit and identify the correct wires to test. Isolate the Circuit: Disconnect the illuminated entry relay and test the wiring harness for a short to battery. This will help determine if the short is in the relay itself or in the wiring. * Component Replacement: If a specific component is identified as the cause of the short, replace it with a new or known-good part. |
| Parts Commonly Replaced | Components that are frequently replaced when addressing the B1373 code. | Illuminated Entry Relay: This is the most frequently replaced component, especially if the relay is found to be faulty during testing. Wiring Harness Sections: Damaged sections of the wiring harness are often replaced or repaired to eliminate short circuits. Fuses: Blown fuses are replaced as needed, but it's crucial to identify and address the underlying cause of the fuse blowing. Door Jamb Switches: Faulty door jamb switches can sometimes contribute to the problem and may need to be replaced. |
| Tools Required | Essential tools for diagnosing and repairing the B1373 code. | Multimeter: Used to measure voltage, resistance, and continuity in the electrical circuit. Scan Tool: Used to read diagnostic trouble codes and clear them after repairs. Wiring Diagrams: Provide a detailed map of the illuminated entry circuit. Wire Strippers/Crimpers: Used to repair or replace damaged wires and connectors. Test Light: A simple tool for checking for voltage in the circuit. Pliers/Screwdrivers: Used to remove and install components. * Terminal Release Tool: Used to disconnect connectors without damaging the terminals. |
Detailed Explanations
Definition of B1373: The B1373 code signifies that the vehicle's computer has detected an unintended voltage supply (short to battery) within the illuminated entry relay circuit. This means a wire or component that should not be receiving constant power is, in fact, connected to a power source, like the battery. This can disrupt the normal operation of the illuminated entry system.
Symptoms: The symptoms associated with the B1373 code provide valuable clues for diagnosis. Interior lights that remain constantly on, even when the doors are closed, are a primary indicator. Conversely, the lights might fail to activate altogether when the doors are opened. A more insidious symptom is a parasitic battery drain, where the short circuit draws power even when the vehicle is off, leading to a dead battery. Blown fuses in the illuminated entry circuit are also common. Dimming lights and unusual relay noises are other possible manifestations.
Common Vehicle Brands Affected: While the B1373 code is generic, it shows up more frequently in Ford, General Motors, and Chrysler vehicles. This is not to say other brands are immune, but these manufacturers seem to have wiring or component designs that make them more susceptible to this particular issue. Specific models like the Ford F-150, Chevrolet Silverado, and Jeep Grand Cherokee are commonly reported with this code.
Diagnostic Procedures: Diagnosing the B1373 code requires a systematic approach. Start with a thorough visual inspection of the wiring harness and connectors associated with the illuminated entry relay. Check for any signs of damage, corrosion, or loose connections. Use a multimeter to test the relay itself for proper function. Next, perform voltage tests at various points in the circuit to pinpoint the location of the short. Wiring diagrams are essential for understanding the circuit layout. A scan tool can read other related codes and clear the B1373 code after repairs.
Troubleshooting Tips: When troubleshooting the B1373 code, focus on areas where the wiring is exposed to harsh conditions. Check door jamb switches, as a faulty switch can mimic a short. Use wiring diagrams to identify the correct wires to test. Isolate the circuit by disconnecting the relay and testing the wiring harness. If a component is found to be faulty, replace it with a known-good part. Remember to double-check your work after each step.
Parts Commonly Replaced: The most frequently replaced part when addressing the B1373 code is the illuminated entry relay itself. Damaged sections of the wiring harness are also common replacement items. Blown fuses need to be replaced, but always identify and fix the underlying cause of the fuse blowing. Occasionally, faulty door jamb switches may also require replacement.
Tools Required: Successfully diagnosing and repairing the B1373 code requires a few essential tools. A multimeter is used to measure voltage, resistance, and continuity. A scan tool reads and clears diagnostic trouble codes. Wiring diagrams are indispensable for understanding the circuit. Wire strippers and crimpers are needed for wiring repairs. A test light can quickly check for voltage. Pliers and screwdrivers are used to remove and install components, and a terminal release tool helps disconnect connectors without damage.
Frequently Asked Questions
What does the B1373 code mean? It indicates a short to battery in the illuminated entry relay circuit, meaning the circuit is receiving unintended power.
What are the common symptoms of the B1373 code? Common symptoms include interior lights staying on, not working at all, or a dead battery.
How do I diagnose the B1373 code? Start with a visual inspection, then use a multimeter to test the relay and wiring for shorts.
Can a faulty relay cause the B1373 code? Yes, a faulty relay can internally short to battery and trigger the B1373 code.
What tools do I need to fix the B1373 code? You'll need a multimeter, scan tool, wiring diagrams, and basic hand tools.
Conclusion
The B1373 code, indicating a short to battery in the illuminated entry relay circuit, can manifest in various ways, from malfunctioning interior lights to battery drain. A systematic diagnostic approach, using the right tools and focusing on common problem areas, is key to identifying and resolving the issue. Addressing the root cause of the short circuit will restore the illuminated entry system to proper function and prevent further electrical problems.