B1372 Illuminated Entry Relay Circuit Open

Introduction

The B1372 diagnostic trouble code (DTC) indicates a problem within the illuminated entry system of a vehicle. Specifically, it signals an open circuit in the relay that controls the power supply to the illuminated entry components, which usually includes interior lights that activate when the doors are unlocked or opened. Understanding this code is crucial for maintaining vehicle functionality and comfort.

Comprehensive Table of B1372 Information

The illuminated entry system provides interior lighting when the vehicle is approached or entered, enhancing convenience and safety. This system typically activates when the doors are unlocked via remote key fob or when a door is opened. The system is designed to illuminate the interior for a set period, allowing occupants to easily locate controls or personal belongings.

Detailed Explanations

Definition: The B1372 code specifically points to an open circuit within the relay circuit that controls the illuminated entry system. This "open circuit" means there's a break in the electrical path, preventing the circuit from completing and thus preventing the relay from activating the illuminated entry system. Think of it like a broken wire in a lamp – electricity can't flow, and the light won't turn on. The illuminated entry system usually involves the interior lights turning on when you unlock the car or open a door, making it easier to see inside at night.

Symptoms: The most obvious symptom is that the interior lights don't turn on when you unlock the car with the key fob or open a door. This makes it difficult to see inside the car in low-light conditions. You might also experience intermittent issues where the lights sometimes work and sometimes don't, indicating a loose connection or a relay that's starting to fail. In some cases, the illuminated entry system might not respond at all, regardless of whether you use the key fob or open the door. The lights may also fail to illuminate when you turn off the ignition and remove the key, if that is part of your vehicle's illuminated entry functionality.

Diagnostic Steps: The diagnostic process involves several steps to pinpoint the exact cause of the open circuit.

1. Confirm the code: Use an OBD-II scan tool to verify that the B1372 code is present. This ensures that you're addressing the correct problem.
2. Inspect the relay: Locate the illuminated entry relay (refer to your vehicle's repair manual for its exact location) and visually inspect it for any signs of damage, corrosion, or melting.
3. Test the relay: Use a multimeter to test the relay's functionality. You can check for continuity across the relay's terminals when it's activated. If the relay fails to switch or shows no continuity, it's likely faulty.
4. Inspect the wiring: Carefully examine the wiring harness and connectors associated with the illuminated entry circuit. Look for any signs of damage, such as frayed wires, corrosion, or loose connections. Pay close attention to areas where the wiring might be exposed to the elements or subject to movement.
5. Check the fuse: Locate the fuse that protects the illuminated entry circuit and verify that it's not blown. A blown fuse could be a symptom of a short circuit, which can also trigger the B1372 code.
6. Test for continuity: Use a multimeter to test the continuity of the wiring between the relay and the Body Control Module (BCM). This will help you identify any breaks or open circuits in the wiring.
7. Check the BCM: In rare cases, the BCM itself might be the cause of the problem. However, before suspecting the BCM, make sure to thoroughly check all other components in the circuit.

Possible Causes: Several factors can lead to an open circuit in the illuminated entry relay circuit.

• Faulty illuminated entry relay: The relay itself might be defective and unable to complete the circuit. Relays can fail due to age, wear and tear, or electrical overload.
• Open or shorted wiring: Damaged wiring, such as a cut or broken wire, can create an open circuit. A short circuit can also indirectly cause the relay to malfunction or the fuse to blow, leading to the B1372 code.
• Corroded or damaged connectors: Corrosion on the connectors can prevent proper electrical contact, resulting in an open circuit.
• Failed Body Control Module (BCM): The BCM controls various electrical functions in the vehicle, including the illuminated entry system. If the BCM malfunctions, it might not properly activate the relay.
• Blown Fuse: A blown fuse in the illuminated entry circuit can cause an open circuit.

Common Solutions: The appropriate solution depends on the root cause of the problem.

• Replace the faulty relay: If the relay is found to be defective, replace it with a new one. Ensure that the replacement relay is compatible with your vehicle's specifications.
• Repair or replace damaged wiring: Repair any damaged wiring by splicing or replacing the affected sections. Use proper wiring techniques and ensure that the connections are secure.
• Clean or replace corroded connectors: Clean corroded connectors with a wire brush or contact cleaner. If the connectors are severely damaged, replace them with new ones.
• Replace the BCM: If the BCM is identified as the cause of the problem, it will need to be replaced and reprogrammed. This is a more complex repair that typically requires the expertise of a qualified technician.
• Replace the blown fuse: If the fuse is blown, replace it with a new fuse of the same amperage rating. If the fuse blows again, it indicates a short circuit that needs to be addressed.

Frequently Asked Questions

What does the B1372 code mean? It means there's an open circuit in the relay that controls the illuminated entry system in your vehicle. This prevents the interior lights from turning on when you unlock or open the doors.

Can I fix the B1372 code myself? Depending on your mechanical skills, you might be able to diagnose and fix the problem yourself. Start by checking the relay and wiring for damage. If you're uncomfortable working with electrical systems, it's best to consult a professional.

How much does it cost to fix a B1372 code? The cost can vary depending on the cause of the problem. Replacing a relay or repairing wiring is relatively inexpensive, while replacing the BCM can be more costly. Expect to pay anywhere from $50 to several hundred dollars.

Is it safe to drive with a B1372 code? Yes, it is generally safe to drive with a B1372 code, as it primarily affects the convenience of the illuminated entry system. However, it's best to get it fixed as soon as possible to avoid any potential safety issues in low-light conditions.

Where is the illuminated entry relay located? The location of the relay varies depending on the vehicle's make and model. Consult your vehicle's repair manual for the exact location. It's often found in the fuse box or under the dashboard.

Conclusion

The B1372 code indicates a problem with the illuminated entry system, typically due to an open circuit in the relay circuit. By systematically diagnosing the issue and addressing the root cause, you can restore the functionality of your vehicle's illuminated entry system. If you are not comfortable performing electrical diagnostics and repairs, seek assistance from a qualified automotive technician.