B1393 — Power Door Memory Lock Relay Circuit Open

Obd-II trouble code B1393 indicates a problem within the electrical circuit controlling the **power door memory lock relay**. This relay is responsible for maintaining the memory function of the door lock system, often linked to the vehicle’s convenience features like remote locking and unlocking. When this code appears, it suggests that the circuit is open or incomplete, preventing the relay from functioning correctly. Note that the exact label or code may vary depending on the vehicle’s manufacturer, but the underlying issue remains similar.

Manufacturer variations for trouble code B1393

Different vehicle manufacturers may assign similar diagnostic trouble codes or labels to this issue, sometimes with slight variations in notation or associated parameters. The B1393 code is relatively standard in OBD-II systems, but OEMs may use different terminology or coding conventions. Here are some well-known variations:

• Ford: B1393 — Power Lock Relay Circuit Open
• Honda: B1393 — Power Door Lock Relay Circuit Open
• Volkswagen: B1393 — Door Lock Control Module Circuit Issue
• General Motors: B1393 — Power Door Lock Relay Circuit Open

What does trouble code B1393 mean?

In simple terms, B1393 is a diagnostic trouble code that indicates a disruption in the electrical circuit responsible for the **power door lock memory relay**. The engine control unit (ECU), or more specifically the **Body Control Module (BCM)** in many vehicles, continually monitors various electrical circuits responsible for vehicle comfort features. When it detects that the circuit controlling the relay is open—meaning the current isn’t flowing as it should—it triggers the code.

This circuit includes wiring, connectors, relays, and the relay coil itself. An open circuit can be caused by a broken wire, loose connection, faulty relay, or damage to the BCM or door lock module. Usually, this issue surfaces when the vehicle’s memory functions, such as remote locking or unlocking of doors, stop working or behave unexpectedly.

Severity and risks of trouble code B1393

The B1393 code generally presents a moderate level of severity. It does not typically affect the core safety or drivability of the vehicle but impacts comfort and convenience features. If ignored, the issue could worsen over time, potentially leading to complete failure of the door lock memory function, or in some cases, cause related electrical problems affecting other systems.

In terms of risks, driving with this trouble code does not usually present immediate safety concerns, especially if the doors can still be operated manually. However, it’s advisable to diagnose and repair the issue promptly to avoid inconvenience, further electrical faults, or potential damage to related components.

Can the vehicle be driven? Limited. The vehicle remains drivable, but the power door lock features might not work as intended, and the warning should be addressed to prevent future problems.

Symptoms of trouble code B1393

Most vehicles with the B1393 code will display subtle or obvious signs of electrical malfunction related to door locks. Typical symptoms include:

• Inoperative or inconsistent remote locking/unlocking functions
• Door lock memory settings not retained after power cycles
• Warning lights or messages related to door lock systems on the dash
• Unusual clicking sounds from the door lock area when attempting to lock/unlock
• Manual door locks functioning normally while electronic functions fail

Most likely causes of trouble code B1393

Diagnosing the exact cause of B1393 involves considering several potential issues. The causes are often related to electrical faults within the circuit controlling the power door lock relay. Here are the most common causes, ranked from most to least prevalent:

1. Open or shorted wiring in the power door lock relay circuit: Damaged or frayed wires can interrupt current flow, leading to an open circuit condition.
2. Faulty power door lock relay: The relay itself can become defective or worn out, preventing it from closing the circuit properly.
3. Loose or corroded connectors or terminals: Poor connections, corrosion, or loose pins can cause intermittent or open circuits.
4. Malfunctioning Body Control Module (BCM): In some cases, the BCM may have internal faults affecting relay control signals.
5. Related fuses blown or circuits overloaded: An overload or fuse failure can disable the relay circuit.

How to diagnose trouble code B1393

Diagnosing B1393 requires a structured approach that involves visual inspections and electrical tests. Here’s a general guide to assist technicians:

1. Perform a visual inspection: Check wiring harnesses, connectors, and relays related to the power door lock system for obvious damage, corrosion, or loose fittings.
2. Consult live data: Using a scan tool, verify if the relay control circuit status is active or shows faults.
3. Check related fuses: Confirm that all relevant fuses are intact and functional.
4. Test the relay: Swap the power door lock relay with a similar known good relay or test it with a multimeter to verify proper operation.
5. Inspect wiring continuity: Use a multimeter to check for continuity along wiring paths, ensuring no open circuits are present.
6. Perform a circuit resistance test: Measure resistance across relay control circuit to identify potential shorts or opens.
7. Verify BCM output signals: For advanced diagnosis, test the BCM output to confirm it is sending correct signals to the relay coil.

Possible repairs for trouble code B1393

Based on the probable causes, repair strategies will vary. Some solutions are straightforward, while others require advanced diagnostics or professional expertise.

• Replace or repair damaged wiring or connectors: This is a basic repair requiring inspection and soldering or connector replacement, suitable for DIY or professional mechanics.
• Replace the faulty relay: A simple fix involving relay replacement, typically available from parts suppliers or OEM stores.
• Clean or tighten electrical connections: Ensuring all terminals and connectors are corrosion-free and properly seated can restore circuit integrity.
• Replace the Body Control Module (BCM): This is a more complex repair, typically performed by professionals, especially if the BCM is internally faulty.
• Replace blown fuses or address overload issues: Fuse replacement and addressing wiring faults that caused overload prevent recurrence.

Vehicles commonly associated with trouble code B1393 in Europe

While this code is relatively general across models, some vehicle brands and engines tend to be involved more frequently. This information helps focusing diagnostic efforts.

In Europe, common brands include:

• Ford: Focus, Fiesta, Kuga (with relevant engine families)
• Volkswagen: Golf, Polo, Passat
• Peugeot & Citroën: 208, 308, C4, C5
• Renault: Clio, Megane, Kadjar

The specific engine families are varied and depend on the model year, but electrical control issues with door modules are common across these vehicles.

Frequent mistakes with trouble code B1393

Incorrect diagnosis or repair can lead to ineffective fixes or further damage. Common mistakes include:

• Replacing the relay without inspecting wiring or connections: Replacing just the relay without verifying circuit integrity often fails to resolve the root cause.
• Ignoring related fuses or wiring issues: Overlooking blown fuses or wiring damage can cause persistent problems.
• Assuming the BCM is faulty without thorough testing: The BCM is an expensive component; replacing it prematurely is a common mistake.
• Failing to clear codes after repairs: Not erasing stored codes can lead to confusion about whether the repair was successful.

Quick FAQ — trouble code B1393

Can this code disappear on its own?

Sometimes, minor wiring issues or loose connections might temporarily resolve, causing the code to clear. However, if the underlying cause persists, it is likely to reappear after the vehicle’s system runs its checks again.

Can I keep driving?

Yes, in most cases, you can continue driving, especially if the door lock functions are still operational manually. However, the convenience features governed by this circuit will likely not work. It is advisable to schedule repairs promptly.

Why does the code return after clearing it?

The code reappears because the underlying cause—such as a wiring fault, relay failure, or BCM issue—has not been addressed. Clearing only resets the indicator without fixing the root problem.