B1392 — Power Door Memory Lock Relay Circuit Failure #

The wording for this DTC may vary depending on the vehicle manufacturer (OEM). Always refer to the official service manual for your specific make and model.

• Ford: Power Door Memory Lock Relay Circuit Failure
• Lincoln: Power Door Lock Memory Relay Circuit Malfunction
• Mercury: Power Door Lock Memory Relay Circuit Fault

Summary of the code B1392 #

The diagnostic trouble code B1392 indicates a malfunction in the Power Door Memory Lock Relay Circuit. This circuit is responsible for operating the power door lock system with memory functions, allowing doors to lock and unlock automatically according to stored driver preferences. When the Body Control Module (BCM) or related control unit detects an electrical fault—such as an open circuit, short, or relay failure—this code is stored. The issue may impact the convenience and security features of your vehicle, but typically does not affect basic drivability. However, unattended, it can lead to further electrical issues or loss of advanced door functions. Addressing this code ensures your vehicle’s comfort and security systems operate as designed.

Common symptoms for code B1392 #

Drivers may notice several noticeable symptoms when B1392 is active. While the impact may seem minor at first, persistent problems with the power door lock memory function can quickly become frustrating or even compromise vehicle security. Typical symptoms include:

• Power door locks not responding to remote or keyless entry commands
• Door locks failing to remember or return to preset positions
• Locks intermittently engaging or disengaging
• Noises (clicking or buzzing) coming from the door relay area
• Interior or exterior lock/unlock switches unresponsive
• Security system/anti-theft warnings or malfunctions

Probable causes for code B1392 (by frequency) #

The B1392 code is most often triggered by issues within the relay or its associated circuitry. Diagnosing the cause requires careful inspection, as multiple components can be involved. The most common culprits, in order of likelihood, include:

1. Faulty power door lock memory relay (stuck contacts, internal coil failure)
2. Open or shorted wiring in the relay control or load circuits
3. Poor or corroded electrical connectors at the relay or BCM
4. Malfunctioning Body Control Module (BCM) or related control unit
5. Blown fuse in the door lock or memory circuit
6. Mechanical door lock actuator failure (less common, but possible if circuit is overloaded)

Step-by-step diagnostic for code B1392 #

A systematic approach is essential to accurately pinpoint the root cause of B1392. Use a multimeter, wiring diagram, and OEM service procedures. Here’s a recommended workflow:

• Verify the code with a scan tool and record any additional codes (especially body or communication codes)
• Check the operation of all power door locks and memory features
• Inspect the fuse(s) related to the power door lock circuit
• Locate and visually inspect the relay and its connectors for corrosion, damage, or loose pins
• Test relay operation by swapping with an identical known-good relay (if available)
• Test for voltage and ground at the relay control and load circuits using a multimeter
• Check the wiring harness between the relay, BCM, and door actuators for continuity and shorts
• If all hardware tests pass, use a scan tool to monitor BCM outputs and inputs during door lock operation
• If the BCM is suspect, follow OEM test procedures for module diagnosis before replacement
• Clear the code and retest the system after each repair step

Possible repairs for code B1392 #

Resolving B1392 depends on the underlying fault identified during diagnosis. Repairs should always address the root cause—don’t just clear the code and hope for the best! Here are targeted solutions:

• Replace a faulty or sticking power door memory relay
• Repair or replace damaged wiring or connectors in the relay circuit
• Clean and secure all electrical connections at the relay and BCM
• Replace a blown fuse with the correct amperage, and inspect for underlying reasons it blew
• Replace the Body Control Module (BCM) only if all other faults are ruled out—programming may be required
• Replace a faulty door lock actuator if it’s causing excessive current draw or circuit issues

Is it safe to drive with code B1392? #

Limited. While B1392 does not typically affect engine performance or critical safety systems, it can compromise your vehicle’s security and convenience features. If the door locks are not functioning or memory settings are lost, you risk theft, or being locked out/in. If other electrical symptoms appear (like repeated blown fuses or BCM communication errors), avoid driving until repaired to prevent more extensive damage.

Vehicles most commonly affected by code B1392 #

While B1392 is most often reported in Ford, Lincoln, and Mercury models, especially those equipped with advanced memory seat and lock features, it may also appear in other brands utilizing similar relay-controlled door memory circuits. The following vehicles are particularly prone:

• Ford Explorer (2005–2014)
• Ford Expedition (2003–2012)
• Lincoln Navigator (2003–2012)
• Ford Taurus (2008–2014)
• Mercury Mountaineer (2005–2010)
• Other Ford/Lincoln models with memory seat and lock systems

Common mistakes & best practices for code B1392 #

When dealing with B1392, it’s easy to overlook root causes or make hasty repairs. Here are frequent missteps and tips for success:

• Replacing the relay without testing the circuit (may not fix the underlying issue)
• Ignoring corroded or loose connectors, which can cause intermittent faults
• Omitting a thorough fuse and wiring check—blown fuses often indicate a deeper problem
• Neglecting to clear codes and confirm proper operation after each repair
• Forgetting to check for related BCM or communication codes
• Best practice: Always use OEM wiring diagrams and follow the manufacturer’s diagnostic steps

Quick FAQ for code B1392 #

Q: Will replacing the relay always fix B1392?
A: Not necessarily. While the relay is a common failure point, the issue could be wiring, connectors, a fuse, or even the BCM. Diagnose carefully before replacing parts.

Q: Can a weak battery or low voltage cause B1392?
A: Rarely. Low system voltage can create erratic electrical symptoms, but this code specifically points to a circuit or component failure. Always check battery health as part of your overall evaluation.