B1395 Power Door Memory Lock Relay Circuit Short To Ground

Introduction:

The B1395 diagnostic trouble code (DTC) signals a potentially significant issue within a vehicle's power door lock system, specifically indicating a short to ground in the memory lock relay circuit. This malfunction can lead to erratic door lock behavior, draining of the vehicle's battery, and overall inconvenience. Understanding the causes, symptoms, and troubleshooting steps associated with this code is crucial for effective diagnosis and repair.

Detailed Explanations

Definition:

The B1395 DTC signifies that the vehicle's Engine Control Module (ECM) or Body Control Module (BCM) has detected an unintended short to ground within the power door memory lock relay circuit. This means that the electrical signal intended to operate the relay is finding an alternate, direct path to ground, bypassing the intended circuit components. The "memory" aspect of the lock relay typically refers to features like automatically locking the doors after a certain speed or delayed locking after the ignition is turned off.

Common Causes:

• Damaged Wiring: This is the most frequent culprit. Wires can become frayed, cracked, or pinched due to wear and tear, exposure to the elements, or accidental damage during repairs. Corrosion at connectors can also create a path to ground.
• Faulty Relay: The memory lock relay itself can fail internally. An internal short within the relay can create a direct path to ground, triggering the B1395 code.
• Body Control Module (BCM) Issues: While less common, a malfunctioning BCM can send incorrect signals or fail to properly control the relay circuit, leading to the short to ground condition.
• Short to Ground: A short to ground refers to any situation where a wire in the circuit is directly contacting the vehicle's metal chassis or another grounded component. This can occur anywhere along the wire between the BCM and the memory lock relay.

Symptoms:

• Power Door Locks Not Functioning Correctly: This is the most obvious symptom. The door locks may work intermittently, not at all, or behave erratically (e.g., locking and unlocking repeatedly).
• Door Locks Activating Unexpectedly: The door locks might lock or unlock without any user input, potentially due to the faulty signal caused by the short to ground.
• Battery Drain: A short to ground can create a continuous draw on the vehicle's battery, leading to a dead battery, especially if the vehicle sits for extended periods.
• Theft Alarm Issues: Because the power door locks are integrated with the vehicle's security system, a malfunction in the lock circuit can trigger false alarms or prevent the alarm from arming properly.
• BCM Related DTCs Present: Other diagnostic trouble codes related to the BCM may also be present, providing further clues about the underlying problem. These codes could indicate issues with other BCM-controlled functions.

Diagnostic Steps:

• Visual Inspection of Wiring and Connectors: Begin with a thorough visual inspection of all wiring and connectors associated with the power door lock system, particularly around the memory lock relay. Look for signs of damage, such as frayed wires, corroded connectors, or pinched wires.
• Testing the Memory Lock Relay: Use a multimeter to test the relay's functionality. Check for proper continuity between the relay's terminals and verify that it clicks when power is applied. A faulty relay should be replaced.
• Checking the Voltage at the Relay: Use a multimeter to check the voltage at the relay's power and ground terminals. Ensure that the relay is receiving the correct voltage and that the ground connection is solid.
• Continuity Testing of the Wiring Harness: Disconnect the battery and use a multimeter in continuity mode to check for shorts to ground in the wiring harness. Test each wire in the circuit to see if it has continuity with the vehicle's chassis.
• BCM Diagnostics: If the wiring and relay appear to be in good condition, the BCM may be the problem. Use a scan tool to check for any BCM-related diagnostic trouble codes and perform any relevant diagnostic tests.

Repair Strategies:

• Repairing or Replacing Damaged Wiring: If damaged wiring is found, repair it by splicing in new wire sections, using proper crimping techniques, and insulating the connections. If the damage is extensive, consider replacing the entire wiring harness section.
• Replacing the Faulty Memory Lock Relay: If the relay is found to be faulty, replace it with a new, OEM-quality relay. Be sure to disconnect the battery before removing and installing the relay.
• Replacing the BCM (as a Last Resort): Replacing the BCM should be considered as a last resort, as it is a complex and expensive repair. Before replacing the BCM, ensure that all other possible causes have been ruled out. The BCM often requires programming after replacement, which may necessitate a visit to a qualified technician or dealership.
• Tracing and Repairing the Short to Ground: Use a multimeter and wiring diagrams to systematically trace the short to ground. Start by isolating sections of the wiring harness and testing for continuity to ground. Once the short is located, repair the damaged wiring or replace the affected harness section.

Frequently Asked Questions

What does the B1395 code mean?

It means there's a short to ground in the circuit controlling the power door memory lock relay, indicating an unintended electrical path to the vehicle's chassis.

Can I still drive my car with the B1395 code?

Yes, but your power door locks might not work correctly, and there's a risk of battery drain or security system malfunctions, so it's best to address the issue promptly.

How do I fix the B1395 code myself?

Start by visually inspecting the wiring and connectors for damage. Then, test the relay and wiring for shorts to ground using a multimeter. Repair or replace any faulty components.

What if the wiring and relay seem fine?

The problem might be with the Body Control Module (BCM), but this is less common and often requires professional diagnosis.

Is the B1395 code serious?

While it may not immediately disable your vehicle, it can lead to inconvenience, security risks, and potential battery drain, making it important to diagnose and repair.

Conclusion

The B1395 DTC indicates a short to ground in the power door memory lock relay circuit, typically caused by damaged wiring or a faulty relay. Thoroughly inspecting the wiring, testing the relay, and systematically diagnosing the circuit are crucial for identifying and resolving the issue, restoring proper power door lock functionality and preventing further complications. If you're not comfortable performing these diagnostic and repair steps yourself, it's best to consult a qualified automotive technician.