B1371 — Illuminated Entry Relay Circuit Failure #

Note: The code description may vary depending on the vehicle manufacturer (OEM).

• Illuminated Entry Relay Circuit Malfunction (Ford, GM)
• Entry Light Relay Circuit Fault (Toyota)
• Courtesy Lamp Relay Circuit Failure (Chrysler)

Summary of code B1371 #

The B1371 code indicates a fault detected in the illuminated entry relay circuit, a system responsible for automatically turning on interior or courtesy lights when you unlock or approach your vehicle. This relay, controlled by the body control module (BCM), ensures that entry lighting operates smoothly and only when needed. If the BCM detects an abnormal voltage, open, or short in the relay circuit, it will trigger this diagnostic trouble code (DTC). While B-codes like this one are not powertrain-related, they can affect comfort, convenience, and sometimes security features in your car. Addressing this code promptly can help maintain the intended user experience and may prevent further electrical issues.

Common symptoms for code B1371 #

A vehicle showing the B1371 code will often have issues with its interior lighting, particularly the lights that should activate automatically on entry or exit. These symptoms can be subtle or obvious and may vary depending on which part of the circuit is affected. The most common signs include:

• Courtesy lights fail to turn on when doors are unlocked or opened
• Interior lights stay on longer than normal after closing doors
• Entry lights do not dim or turn off as expected
• Occasional flickering or erratic behavior of dome or courtesy lamps
• Possible warning messages related to lighting or BCM on the dashboard

Most probable causes for B1371 #

The B1371 code is typically triggered by faults within the illuminated entry relay circuit itself. The root causes can range from simple wiring issues to failed electronic modules. Based on frequency, here are the most common culprits:

1. Faulty illuminated entry relay (relay contacts stuck or corroded)
2. Damaged or loose wiring/connectors in the relay circuit
3. Body Control Module (BCM) malfunction
4. Blown fuse associated with the entry lighting system
5. Faulty door jamb switch or sensor (not always, but can affect the circuit)

Step-by-step diagnosis for B1371 #

Diagnosing a B1371 code requires a logical, methodical approach with basic diagnostic tools. Always start with the simplest checks before moving on to more complex components. Here’s a proven step-by-step process:

• Verify the code with an OBD-II/EOBD scan tool and check for any other related codes.
• Inspect the operation of entry and dome lights for abnormal behavior.
• Locate the illuminated entry relay (refer to your service manual for location).
• Check the fuse(s) related to interior lighting and the relay circuit; replace if blown.
• Examine relay connectors and visible wiring for signs of corrosion, damage, or loose pins.
• Test the relay for correct operation (swap with a similar known-good relay if possible).
• If the relay and wiring check out, perform continuity and voltage tests on the circuit as per OEM schematics.
• Inspect the BCM for signs of failure if all external components are functional.
• Clear the code, cycle the ignition, and retest the system to confirm the issue is resolved.

Possible repairs for B1371 #

Resolving the B1371 code depends on the exact cause identified during diagnosis. Each solution targets a specific issue within the illuminated entry relay circuit. The most common fixes include:

• Replacing a faulty illuminated entry relay
• Repairing or replacing damaged wiring or connectors in the relay circuit
• Replacing a blown fuse related to the interior lighting system
• Repairing or replacing a faulty door jamb switch (if involved in the circuit)
• Replacing the Body Control Module (BCM) if verified to be defective

Is it safe to drive with code B1371? #

Yes, you can generally drive with code B1371 as it does not directly affect engine or transmission operation. This code relates to comfort and convenience features, specifically the automatic interior lighting. However, if your courtesy lights fail to turn on at night, it may reduce entry visibility and could lead to minor safety or security concerns. It’s best to repair the fault at your earliest convenience to ensure all features work as intended.

Vehicles most commonly affected by B1371 #

While any vehicle equipped with an illuminated entry system can experience this fault, it appears more frequently in certain makes and models. Based on repair data and OEM bulletins, B1371 is often reported in:

• Ford (Focus, Escape, F-150, Explorer)
• Chevrolet/GMC (Silverado, Tahoe, Malibu)
• Toyota (Camry, Corolla, Prius)
• Chrysler/Dodge/Jeep (Grand Caravan, 300C, Ram)
• Honda (Accord, CR-V, Odyssey)

Common mistakes & best practices for B1371 #

Sometimes, technicians or DIYers overlook the basics or misinterpret the code, leading to unnecessary repairs. To avoid headaches, keep these in mind:

• Not checking the fuse first—always start with the simplest and cheapest fix.
• Swapping out the relay without checking the wiring or connectors.
• Ignoring other related codes that may point to a bigger BCM issue.
• Failing to clear the code and retest after repairs—this verifies your work.
• Using incorrect replacement relays; always match OEM part numbers.

Quick FAQ for code B1371 #

Here are some quick answers to the most common questions about B1371:

• Q: Can a weak battery cause B1371?
  A: Unlikely. While a low battery may cause erratic BCM behavior, B1371 typically means a dedicated circuit issue, not a global power loss.
• Q: Will replacing the entry relay always fix the code?
  A: Not always. If wiring, fuses, or the BCM itself are at fault, replacing the relay alone won’t solve the problem.