B1392 Power Door Memory Lock Relay Circuit Failure

Introduction:

The B1392 trouble code indicates a problem within the power door memory lock relay circuit in your vehicle. This circuit is responsible for storing and recalling driver-specific settings, such as seat position, mirror angles, and steering wheel height, often linked to the key fob used. When this circuit malfunctions, it can lead to frustrating issues with your vehicle's personalized settings.

Table: B1392 Power Door Memory Lock Relay Circuit Failure

Detailed Explanations:

Code Definition: The B1392 code is a diagnostic trouble code (DTC) that indicates a fault within the power door memory lock relay circuit. This circuit is responsible for storing and recalling personalized settings for the driver, such as seat position, mirror angles, and steering wheel adjustments. The vehicle's computer, often the Body Control Module (BCM) or Engine Control Unit (ECU), detects an electrical issue within this circuit, triggering the code. This issue prevents the relay from functioning properly, hindering the memory feature.

Faulty Memory Lock Relay: The relay itself is an electromechanical switch. Over time, the internal contacts can become corroded or worn, leading to intermittent or complete failure. A faulty relay may not properly energize the circuit, preventing the memory lock function from working. Testing the relay with a multimeter is crucial to determine its functionality.

Wiring Issues: The wiring harness connecting the relay to the BCM and other components can be damaged by heat, vibration, or physical stress. Corrosion can also build up on the wires, increasing resistance and disrupting the circuit. Short circuits can occur if the insulation on the wires is damaged, causing them to touch each other or ground.

Connector Problems: Connectors are essential for providing secure and reliable electrical connections. However, they are susceptible to corrosion, loose connections, and physical damage. Corrosion can increase resistance, while loose connections can cause intermittent problems. Damaged connectors may not make proper contact, leading to circuit failure.

BCM (Body Control Module) Failure: The BCM is a central control unit responsible for managing various electrical functions in the vehicle, including the power door memory lock system. If the BCM malfunctions, it can disrupt the relay's operation. While less common than other causes, a faulty BCM requires professional diagnosis and, potentially, reprogramming or replacement.

Fuse Issues: A blown fuse is a simple but often overlooked cause of electrical problems. The fuse protects the circuit from overcurrent, and if it blows, the circuit will be disabled. Always check the fuse associated with the power door memory lock relay circuit and replace it with the correct amperage rating.

Low Battery Voltage: The memory lock system relies on a stable voltage supply to function correctly. If the battery voltage is low, the relay may not receive enough power to operate, leading to intermittent or complete failure of the memory lock function. Checking the battery's health and charging system is a good starting point.

Open or Short Circuit: An open circuit means there is a break in the wiring, preventing current from flowing. A short circuit means there is an unintended connection between two wires or between a wire and ground, causing excessive current flow. Both open and short circuits can disable the power door memory lock relay circuit.

Symptoms: The symptoms associated with the B1392 code can vary, but they generally involve issues with the vehicle's memory settings and power door locks.

Memory Settings Not Retained: This is the most common symptom. The vehicle may forget seat positions, mirror adjustments, and other personalized settings after the ignition is turned off. This means that each time you start the car, you may need to manually readjust these settings.

Power Door Locks Malfunctioning: The power door locks may not operate correctly, either failing to lock/unlock or exhibiting intermittent behavior. This can be a safety concern and a significant inconvenience.

Intermittent Issues: The problem may only occur sporadically. The memory settings may work sometimes but not others, making it difficult to diagnose the root cause.

No Response to Key Fob Memory Commands: Pressing the memory recall buttons on the key fob may have no effect. This indicates that the key fob is not communicating correctly with the memory lock system.

Warning Lights: The security or other warning lights may illuminate on the dashboard, indicating a problem with the vehicle's electrical system.

Unexpected Door Lock Behavior: Doors may lock or unlock unexpectedly. This can be a symptom of a short circuit or other wiring issue in the power door lock system.

Driver Profile Issues: Problems saving or recalling driver profiles. If your vehicle has the ability to save different driver profiles, the B1392 code may prevent you from saving or recalling these profiles correctly.

Diagnostic Steps: A thorough diagnostic process is essential to accurately identify the cause of the B1392 code and implement the appropriate repair.

Visual Inspection: Carefully inspect the wiring and connectors related to the power door memory lock relay for any signs of damage, corrosion, or loose connections. Look for frayed wires, cracked insulation, and corroded terminals.

Fuse Check: Verify that the fuse protecting the circuit is intact. Use a multimeter to check for continuity across the fuse. Replace the fuse if it is blown.

Relay Testing: Test the relay itself to ensure it is functioning correctly. This can often be done using a multimeter to check for continuity and proper operation when voltage is applied. You should hear a click when the relay is energized. Consider swapping it with a known good relay if possible.

Wiring Diagram Consultation: Consult a wiring diagram specific to your vehicle to identify the correct wires and components in the circuit. This will help you to trace the circuit and identify any potential problems.

Voltage and Ground Testing: Use a multimeter to check for proper voltage and ground at the relay and other points in the circuit. Ensure that the relay is receiving the correct voltage when it is supposed to be energized. Also, verify that the relay has a good ground connection.

BCM Testing: If other tests fail to identify the problem, the BCM may need to be tested or reprogrammed by a qualified technician. This often requires specialized diagnostic equipment.

Scan Tool Data Analysis: Use a scan tool to read any stored data or fault codes related to the BCM and the power door memory system. This can provide valuable clues about the nature of the problem.

Component Location: Locate the power door memory lock relay, which is typically found in the fuse box or under the dashboard. Consult your vehicle's service manual for the exact location.

Frequently Asked Questions:

• What does the B1392 code mean? It indicates a malfunction in the power door memory lock relay circuit, preventing the storage and recall of personalized settings.

• Can I fix this problem myself? Depending on your mechanical skills, you might be able to check fuses, wiring, and connectors. However, more complex diagnostics and repairs, like BCM testing, require professional expertise.

• How much will it cost to fix this problem? The cost can vary depending on the cause of the problem. A simple fuse replacement might be inexpensive, while replacing the BCM can be costly.

• Is it safe to drive with the B1392 code? While it may not directly affect the vehicle's drivability, malfunctioning door locks or memory settings can be inconvenient and potentially a safety concern. It's best to address the issue as soon as possible.

• Where is the memory lock relay located? The location varies by vehicle make and model, but it's usually in the fuse box or under the dashboard. Consult your vehicle's service manual.

Conclusion:

The B1392 code signifies a problem in the power door memory lock relay circuit, potentially affecting door locks and personalized settings. A systematic diagnostic approach, starting with simple checks and progressing to more complex testing, is crucial for identifying and resolving the root cause of the issue.