Introduction
The B1394 diagnostic trouble code (DTC) indicates a "Power Door Memory Lock Relay Circuit Short To Battery." This means the vehicle's computer has detected an unintended electrical connection between the power door memory lock relay circuit and the vehicle's battery voltage. This short circuit can cause various problems, including the door locks malfunctioning, the vehicle's battery draining, or even damage to the electrical components. Understanding the causes, symptoms, and diagnostic procedures for this code is crucial for proper vehicle repair.
Comprehensive Table
| Topic | Description | Potential Impact |
|---|---|---|
| Definition of B1394 | Power Door Memory Lock Relay Circuit Short To Battery. Indicates an unwanted electrical path between the relay circuit and the battery's positive terminal. | Door lock malfunction, battery drain, potential damage to the power door lock module or body control module (BCM). |
| Affected Components | Power door lock relay, wiring harness connecting the relay to the power door lock module/BCM and the battery, power door lock module/BCM itself, and the door lock actuators. The memory function within the door lock module is also implicated. | Relay may be constantly energized, wiring may overheat and melt, module may be damaged, door locks may operate erratically or not at all, memory settings lost. |
| Common Causes | Damaged wiring harness: Frayed, cracked, or rodent-chewed wires exposing the conductor and shorting to ground. Faulty power door lock relay: Internal short within the relay. Short in the power door lock actuator: Internal short within the actuator causing backfeed to the relay circuit. Water intrusion: Corrosion causing shorts in connectors or wiring. | Intermittent door lock operation, battery drain, blown fuses, inability to program or recall memory settings for door locks. |
| Symptoms | Door locks operating erratically (locking/unlocking spontaneously), door locks not responding to remote or switch inputs, battery drain when the vehicle is off, blown fuses related to the door lock system, inability to program or recall door lock memory settings (if equipped). | Inconvenience, security risk, potential for a dead battery, expensive repairs. |
| Diagnostic Tools | Multimeter, wiring diagram specific to the vehicle, scan tool capable of reading body control module (BCM) data, test light, circuit tester. | Accurate diagnosis and efficient repair. |
| Diagnostic Procedure Steps | 1. Verify the DTC: Use a scan tool to confirm the B1394 code is present. 2. Inspect the wiring harness: Visually check the wiring harness for damage (fraying, cracking, rodent damage) along its entire length, especially near the door hinges and any points where it passes through the body. 3. Check the power door lock relay: Locate the relay using the wiring diagram and test it using a multimeter. Check for proper resistance and continuity. 4. Isolate the circuit: Disconnect the power door lock relay and measure the voltage at the relay connector. If voltage is present when it shouldn't be, the short is in the wiring harness. 5. Test the power door lock actuators: Disconnect the actuators one by one and check for shorts using a multimeter. 6. Inspect connectors: Check all connectors in the circuit for corrosion or damage. 7. Consult wiring diagram: Use the wiring diagram to trace the circuit and identify potential short locations. 8. Check for backfeed: With the relay disconnected, check for voltage backfeeding into the circuit from other components. 9. Inspect the BCM/Power Door Lock Module: Inspect the module for signs of damage or corrosion. 10. Perform a wiggle test: While monitoring voltage readings, wiggle the wiring harness to see if the short intermittent. | Pinpoint the exact location of the short circuit for effective repair. |
| Repair Strategies | Repair or replace the damaged wiring harness: Repair frayed or damaged wires by splicing and insulating them. Replace the entire harness if the damage is extensive. Replace the faulty power door lock relay: Use a new, OEM-quality relay. Replace the shorted power door lock actuator: Use a new, OEM-quality actuator. Clean corroded connectors: Clean corroded connectors with electrical contact cleaner. Replace the BCM/Power Door Lock Module: If the module is damaged, it may need to be replaced and reprogrammed. | Restoring proper door lock function and preventing future issues. |
| Preventative Measures | Regularly inspect the wiring harness for damage, especially in areas prone to wear and tear. Keep the vehicle clean and dry to prevent corrosion. Address any door lock problems promptly to prevent further damage. | Minimizing the risk of future B1394 codes and related problems. |
| Related DTCs | Other door lock related DTCs, battery drain codes, and BCM/power door lock module codes. | Provides a more complete picture of the electrical system issues. |
Detailed Explanations
Definition of B1394: The B1394 code is a manufacturer-specific diagnostic trouble code (DTC) that indicates a "Power Door Memory Lock Relay Circuit Short To Battery." This means the vehicle's computer, usually the body control module (BCM) or a dedicated power door lock module, has detected an unintended electrical connection between the power door memory lock relay circuit and the positive (+) terminal of the vehicle's battery. This short circuit causes the relay circuit to receive power when it shouldn't, leading to potential malfunctions.
Affected Components: Several components can be affected by a B1394 code. These include the power door lock relay itself, the wiring harness that connects the relay to the BCM/power door lock module and the battery, the BCM/power door lock module itself, and the door lock actuators. The "memory" aspect of the code also implicates any memory functions associated with the door lock module, such as personalized door lock settings.
Common Causes: The most common cause of a B1394 code is a damaged wiring harness. Frayed, cracked, or rodent-chewed wires can expose the conductor and short to the battery voltage. A faulty power door lock relay with an internal short can also cause the code. Other potential causes include a short in the power door lock actuator causing backfeed to the relay circuit, and water intrusion leading to corrosion in connectors or wiring.
Symptoms: The symptoms of a B1394 code can vary depending on the severity of the short circuit. Common symptoms include door locks operating erratically (locking/unlocking spontaneously), door locks not responding to remote or switch inputs, a battery drain when the vehicle is off, blown fuses related to the door lock system, and the inability to program or recall door lock memory settings (if the vehicle is equipped with this feature).
Diagnostic Tools: Diagnosing a B1394 code requires several specialized tools. A multimeter is essential for measuring voltage, resistance, and continuity in the circuit. A wiring diagram specific to the vehicle is crucial for tracing the circuit and identifying components. A scan tool capable of reading body control module (BCM) data is needed to confirm the code and access related information. A test light or circuit tester can also be helpful for checking for power and ground in the circuit.
Diagnostic Procedure Steps: The diagnostic procedure for a B1394 code involves a systematic approach. First, verify the DTC using a scan tool. Then, inspect the wiring harness for any visible damage. Next, check the power door lock relay using a multimeter. Isolate the circuit by disconnecting the relay and measuring voltage at the connector. Test the power door lock actuators for shorts. Inspect connectors for corrosion. Consult the wiring diagram to trace the circuit. Check for backfeed with the relay disconnected. Inspect the BCM/Power Door Lock Module for damage. Finally, perform a wiggle test while monitoring voltage readings to identify intermittent shorts.
Repair Strategies: Repairing a B1394 code typically involves addressing the underlying cause of the short circuit. This may involve repairing or replacing the damaged wiring harness by splicing and insulating wires or replacing the entire harness. A faulty power door lock relay should be replaced with a new, OEM-quality relay. A shorted power door lock actuator should also be replaced with a new, OEM-quality actuator. Corroded connectors should be cleaned with electrical contact cleaner. In some cases, the BCM/Power Door Lock Module may need to be replaced and reprogrammed if it is damaged.
Preventative Measures: Preventative measures can help minimize the risk of future B1394 codes. Regularly inspect the wiring harness for damage, especially in areas prone to wear and tear. Keep the vehicle clean and dry to prevent corrosion. Address any door lock problems promptly to prevent further damage to the electrical system.
Related DTCs: The B1394 code may be accompanied by other related DTCs, such as other door lock related codes, battery drain codes, and BCM/power door lock module codes. Investigating these related codes can provide a more complete picture of the electrical system issues and help pinpoint the root cause of the problem.
Frequently Asked Questions
What does the B1394 code mean? The B1394 code indicates a short to battery in the power door memory lock relay circuit, meaning there's an unintended electrical connection. This can lead to door lock malfunctions and battery drain.
Can a bad relay cause a B1394 code? Yes, a faulty power door lock relay with an internal short can cause the B1394 code. Replace the relay to resolve the issue.
Is it safe to drive with a B1394 code? While driving is generally safe, the battery drain and unpredictable door lock behavior can be inconvenient and potentially create a security risk. Addressing the issue promptly is recommended.
How do I find the power door lock relay? Consult your vehicle's repair manual or wiring diagram to locate the power door lock relay. Its location varies depending on the vehicle make and model.
Can water damage cause a B1394 code? Yes, water intrusion can cause corrosion in connectors and wiring, leading to a short circuit and triggering the B1394 code. Dry and clean the affected areas.
Conclusion
The B1394 code signals a serious electrical issue within the power door lock system that needs prompt attention. By understanding the causes, symptoms, and diagnostic procedures, you can effectively troubleshoot and repair the problem, ensuring the proper functioning of your vehicle's door locks and preventing potential battery drain.