B1374 — Illuminated Entry Relay Short To Ground #

Note: The official description of this DTC may vary by manufacturer. Always refer to your vehicle’s OEM service information for exact wording.

• Illuminated Entry Relay Circuit Short to Ground (Ford, Lincoln, Mercury)
• Illuminated Entry Relay Input Low (General Motors)
• Illuminated Entry Control Relay Short to Earth (Toyota, Lexus)

Summary of DTC B1374 #

The B1374 code signals a problem with the Illuminated Entry Relay circuit, specifically a short to ground. The Illuminated Entry Relay is part of your vehicle’s courtesy lighting system, designed to light up the interior when you unlock or open the doors. A short to ground means electrical current is flowing directly to the body or chassis, bypassing the intended circuit, and often causes the relay or its connected lights to malfunction. This issue is usually detected by the Body Control Module (BCM), which monitors the system for electrical faults. If left unattended, this code could lead to inoperative courtesy lights, battery drain, or further electrical issues within the vehicle’s interior lighting system.

Common Symptoms for Code B1374 #

When the B1374 code appears, you’ll likely notice issues related to the interior lighting system, particularly when entering or exiting the vehicle. Drivers often report that courtesy lights fail to operate as expected, or stay on when they shouldn’t. You may also experience other electrical oddities, all pointing to a malfunction in the illuminated entry system. Typical symptoms include:

• Courtesy lights do not turn on when doors are opened or vehicle is unlocked
• Interior lights remain illuminated even after doors are closed
• Noticeable battery drain if lights stay on for extended periods
• Clicking sounds from the relay area (glove box, dash, or footwell) as the relay repeatedly tries to switch
• Occasional warning messages or chimes related to the lighting system on the dash

Most Probable Causes for B1374 #

The B1374 code is most frequently triggered by electrical issues in the illuminated entry relay circuit. These problems can stem from wiring faults, component failures, or even corrosion in connectors. Based on experience and frequency, the most common causes are:

1. Shorted wiring in the illuminated entry relay circuit (damaged insulation, pinched wires, or exposed conductors making contact with the chassis)
2. Faulty illuminated entry relay (internal short or stuck contacts)
3. Corroded or loose connectors at the relay or BCM
4. Failure in the Body Control Module (BCM) output for the relay circuit
5. Water intrusion leading to corrosion in door or kick panel harnesses

Step-by-Step Diagnostic for B1374 #

Tackling the B1374 code requires a logical, step-by-step approach to pinpoint the fault without replacing unnecessary parts. Always follow safety precautions around vehicle electrical systems. Here’s a reliable diagnostic roadmap:

• Verify the code with a professional-grade scan tool and note any related codes (especially BCM or lighting codes).
• Consult the wiring diagram for your specific make/model to locate the illuminated entry relay and its circuit.
• Inspect the illuminated entry relay for signs of overheating, corrosion, or physical damage.
• Test the relay itself by swapping with a known good relay (if possible) and see if the issue changes.
• Check wiring from the relay to ground points and to the BCM for visible damage, chafing, or pinched sections, especially where loom passes through doors or under carpets.
• Use a multimeter to check for continuity between the relay’s output and ground (should not have direct continuity—otherwise, a short exists).
• Inspect all connectors for water, corrosion, or bent pins, especially in high-humidity areas or where water ingress is common.
• If all physical checks pass, use a scan tool to command the relay ON/OFF and monitor voltage drops or unexpected behavior at the relay terminals.
• If the problem persists after checks and repairs, suspect a BCM fault and consider professional testing or replacement.

Possible Repairs for B1374 #

Resolving a B1374 code typically involves repair or replacement of faulty wiring or components related to the illuminated entry relay circuit. Always address the root cause, not just the symptom, to avoid repeat failures. Common solutions include:

• Repairing or replacing damaged or shorted wiring in the illuminated entry relay circuit
• Replacing a faulty illuminated entry relay
• Cleaning or repairing corroded connectors at the relay or BCM
• Sealing or rerouting wiring harnesses to prevent future water intrusion
• In rare cases, replacing the Body Control Module (BCM) if proven faulty

Is It Safe to Drive with Code B1374? #

Limited: While B1374 is not immediately dangerous, it can lead to inoperative interior lights and, in some cases, drain your battery if the lights stay on. If you notice persistent battery drain, or if your courtesy lights are malfunctioning in a way that impairs night-time visibility when entering/exiting your car, it’s best to address the issue promptly. For most vehicles, you can continue driving short-term, but avoid letting the vehicle sit without repair, especially if the lights remain on after you exit.

Vehicles Most Commonly Affected by B1374 #

While B1374 can occur on a variety of vehicles equipped with illuminated entry systems, it’s most often reported in models where the courtesy lighting system is especially complex or where water ingress is a known issue. Vehicles where this code is most frequently encountered include:

• Ford (F-150, Explorer, Taurus, Focus)
• Lincoln (Navigator, MKX)
• Mercury (Mountaineer, Sable)
• Chevrolet (Silverado, Malibu, Impala)
• Toyota (Camry, Highlander, Corolla)
• Lexus (RX, ES series)

Common Mistakes & Best Practices for B1374 #

Many DIYers and even seasoned techs can fall into common traps when diagnosing and repairing the B1374 code. Avoiding these pitfalls will save you time and ensure a reliable fix:

• Replacing the relay before properly inspecting wiring and connectors (most shorts are wiring-related)
• Overlooking water intrusion in door/kick panel harnesses, especially after heavy rain or car washes
• Skipping use of a wiring diagram—guessing at wire colors or relay locations leads to misdiagnosis
• Not verifying repair by clearing the code and confirming proper operation with a scan tool and manual tests
• Ignoring related codes that could point to BCM or other module issues

Quick FAQ for B1374 #

Here are some rapid answers to the most common questions about B1374 — Illuminated Entry Relay Short To Ground:

• Can I disable the illuminated entry system to get rid of the code?
  Disabling the system is not recommended, as it may cause further electrical issues or warning lights. Proper diagnosis and repair is the best approach.
• Will replacing the relay always fix B1374?
  Not always. Many cases are due to wiring shorts rather than a failed relay. Always inspect the circuit thoroughly before replacing parts.