B1393 — Power Door Memory Lock Relay Circuit Open #

Note: The wording of this code may vary depending on the vehicle manufacturer.

• Power Door Memory Lock Relay Circuit Open (Ford, Lincoln, Mercury)
• Power Door Lock Memory Relay Open Circuit (Toyota, Lexus)
• Memory Lock Relay Circuit Malfunction (Honda, Acura)

Summary of the B1393 Code #

The B1393 Diagnostic Trouble Code (DTC) signals an open circuit in the memory lock relay for the vehicle’s power door lock system. In automotive terms, a relay is an electrically operated switch that controls high-current devices like door locks. The “memory” aspect means the system can remember and return to preset lock or unlock positions, often linked to driver profiles. When this circuit is open, commands to lock or unlock doors—or to recall memory positions—can fail. Identifying and correcting this code ensures secure and consistent door locking performance and proper function of driver convenience features.

Common Symptoms for Code B1393 #

When the B1393 code is active, you may notice issues with your power door locks, especially if your vehicle has memory-associated features. The most frequent symptoms can range from subtle changes in lock behavior to a complete lack of response.

• Power door locks do not operate when using the key fob or interior switches.
• Memory seat or mirror settings not linked to door lock/unlock events.
• Intermittent or inconsistent locking/unlocking function.
• Warning lights or error messages about door lock system.
• Audible chimes when attempting to lock/unlock.

Most Likely Causes for Code B1393 #

The root causes of the B1393 code generally relate to circuit integrity, relay function, or wiring issues. These should be checked in order of likelihood:

1. Faulty power door memory lock relay: The relay itself may have failed internally.
2. Open or damaged wiring/connectors: Broken, corroded, or disconnected wires to the relay or control module.
3. Defective door module: The electronic control unit managing the locks may be at fault.
4. Blown fuse: A fuse protecting the memory lock relay circuit could be open.
5. Incorrectly installed aftermarket accessories: Alarm or remote start systems may disrupt the relay circuit.

Step-by-Step Diagnostic for Code B1393 #

Diagnosing B1393 requires a methodical approach, starting with the most accessible components and working toward the more complex. Always refer to your vehicle’s OEM wiring diagram for accurate pinouts and circuit paths.

• 1. Verify the code: Confirm B1393 is active using a professional OBD-II scanner.
• 2. Check fuse and relay location: Identify and inspect the fuse and relay associated with the power door memory lock circuit.
• 3. Test the relay: Remove the relay and bench-test it or swap with an identical known-good relay if available.
• 4. Inspect wiring and connectors: Look for visible damage, corrosion, or loose terminals at the relay, door module, and fuse block.
• 5. Check continuity: Use a multimeter to verify continuity between relay terminals and the door control module.
• 6. Scan for related codes: Other body or communication codes may point to broader issues.
• 7. Test module outputs: If all else checks out, verify that the door module is providing the proper control signals to the relay.

Possible Repairs for Code B1393 #

Once the cause is confirmed, repairs should directly target the faulty component or connection. Always clear the code after repairs and retest the system to ensure proper operation.

• Replace faulty relay: Install a new OEM relay specified for the memory lock circuit.
• Repair or replace damaged wiring/connectors: Splice, solder, or replace any compromised wires or connectors.
• Replace blown fuse: Use a fuse of correct amperage per OEM specifications.
• Reprogram or replace door module: If the module is defective, it may require replacement and programming.
• Remove or correct aftermarket device wiring: Restore original wiring if previous modifications are causing the fault.

Is It Safe to Drive with Code B1393? #

Driving with code B1393 is generally safe, but can be limiting. The primary concern is loss of power locking functionality, which may affect your ability to lock or unlock doors conveniently. This could be a security issue, especially in urban areas or when transporting valuables. However, in most cases, the vehicle remains drivable and other systems are not compromised. If your locks are stuck in the locked or unlocked position, exercise caution and consider prompt repairs.

Vehicles Most Commonly Affected by Code B1393 #

B1393 is most prevalent in vehicles with advanced power door lock and memory systems, especially those from mid-2000s onward. While it’s seen in many brands, the following are notably affected:

• Ford (Explorer, Taurus, Expedition, Edge)
• Lincoln (MKX, Navigator, MKZ)
• Mercury (Mountaineer, Sable)
• Toyota (Avalon, Camry, Highlander with memory seats)
• Lexus (ES, RX, GS)
• Honda/Acura (Accord, MDX, RLX with memory features)

Common Mistakes & Best Practices for Code B1393 #

Misdiagnosis and overlooked details can prolong repairs for B1393. Here’s what technicians and DIYers should keep in mind:

• Assuming the relay is always at fault—wiring issues are just as common.
• Skipping fuse checks before replacing more expensive parts.
• Not consulting the OEM wiring diagram for your specific make/model.
• Overlooking aftermarket alarm/remote start interference.
• Neglecting to clear codes and verify repair with a post-repair scan.

Express FAQ — Code B1393 #

Still have questions about B1393? Here are some quick answers:

• Q: Will disconnecting the battery reset this code?
  A: No, B1393 will not clear simply by disconnecting the battery—it must be resolved at the source and cleared with a scan tool.
• Q: Can a faulty door lock switch trigger this code?
  A: Not directly, but a switch shorting out or jamming could cause related issues. B1393 specifically refers to the relay circuit itself being open.
• Q: Do I need to have the vehicle reprogrammed after repair?
  A: Only if the door module is replaced or updated. Fuse, relay, or wiring repairs usually do not require further programming.