B2491 — RF PARK LAMP OUTPUT CIRCUIT Short to Battery #

The code label may vary depending on the vehicle manufacturer.

• RF Park Lamp Output Circuit Short to Battery (General, Ford, Chrysler, GM)
• Right Front Parking Lamp Circuit High (Toyota, Lexus)
• Right Front Marker Lamp Circuit Shorted High (Nissan, Infiniti)

Summary of DTC B2491 #

B2491 indicates that the vehicle’s onboard diagnostics system (OBD-II) has detected a short-to-battery condition in the right front (RF) park lamp output circuit. In simple terms, the circuit responsible for powering the right front parking light is receiving more voltage than expected—suggesting a wiring fault or a malfunctioning component. This code is typically set when the Body Control Module (BCM) or Lighting Control Module (LCM) senses a voltage higher than normal, often due to a short directly to battery voltage. Understanding and addressing this code promptly is important, as it can affect both lighting performance and electrical safety. Depending on the vehicle, the park lamp circuit may also impact daytime running lights or side marker functionality.

Common Symptoms for DTC B2491 #

When B2491 is stored in the vehicle’s memory, a driver or technician may notice several symptoms. In some cases, the issue is obvious, while in others, it may only trigger a warning light on the dashboard. Typical signs include:

• Right front parking light remains illuminated even when the switch is OFF
• Right front parking light fails to turn off after the vehicle is locked
• Right front parking light does not function when commanded ON (in rare wiring scenarios)
• Lighting-related warning or indicator illuminated in the instrument cluster
• Possible battery drain if the lamp stays on for extended periods

Most Likely Causes of DTC B2491 #

The B2491 code is most often triggered by wiring issues, but several component failures are also possible. Here’s a rundown of the most probable causes, ordered by frequency:

1. Damaged wiring harness—insulation worn or wire pinched, causing a direct connection to battery voltage
2. Short-circuit at the lamp socket—corrosion or water ingress bridging power and ground terminals
3. Faulty right front park lamp bulb or LED assembly—internal short causing circuit feedback
4. Defective Body Control Module (BCM) or Lighting Control Module (LCM)—internal short or failed output driver
5. Aftermarket accessory installation (e.g., alarm, lighting kit) tapping into the park lamp circuit incorrectly

Step-by-Step Diagnostic for B2491 #

Proper diagnosis is the key to an effective repair. Here’s a proven method for pinpointing the cause of B2491:

• Step 1: Read codes and freeze frame data with an OBD-II scanner. Clear the code and check if it returns immediately.
• Step 2: Visually inspect the right front park lamp, socket, and wiring harness for damage, corrosion, or signs of overheating.
• Step 3: Using a digital multimeter, measure voltage at the lamp socket with the park lamps OFF. Any voltage present may indicate a short to battery.
• Step 4: Disconnect the lamp assembly and check if the code persists (may help isolate bulb/LED faults).
• Step 5: Trace the harness from the lamp back to the BCM/LCM, inspecting for pinched wires, aftermarket splices, or contact with sharp metal edges.
• Step 6: In rare cases, substitute with a known-good BCM/LCM or test BCM output signals to confirm module integrity.

Possible Repairs for DTC B2491 #

Once the root cause is identified, the following repairs are commonly performed to resolve B2491:

• Repair or replace damaged wiring within the right front park lamp circuit
• Clean or replace the right front park lamp socket if corrosion or water ingress is found
• Replace a faulty right front park lamp bulb or LED assembly
• Remove or correct any aftermarket accessory wiring that taps into or damages the park lamp circuit
• Replace the Body Control Module (BCM) or Lighting Control Module (LCM) if internal failure is confirmed (rare)

Is It Safe to Drive With DTC B2491? #

Limited. While B2491 does not typically immobilize the vehicle or affect critical safety systems, driving with a persistent park lamp circuit fault is not recommended for extended periods. A stuck-on lamp can drain the battery, leaving you stranded. Additionally, malfunctioning exterior lights reduce your visibility to other drivers, especially at night or in poor weather. Prompt diagnosis and repair will help avoid further electrical issues or inconvenience.

Vehicles Most Commonly Affected by B2491 #

This code appears most frequently on modern vehicles equipped with multiplexed (networked) lighting systems and solid-state lighting control modules. Models known to commonly log this code include:

• Ford F-Series trucks (2010+)
• Chevrolet Silverado and GMC Sierra
• Chrysler Pacifica, Town & Country
• Toyota Camry, Tacoma
• Nissan Altima, Murano

However, any vehicle with separate right/left output circuits for exterior lamps can potentially register this fault.

Common Mistakes & Best Practices for B2491 #

Mistakes during diagnosis or repair of B2491 can lead to wasted time and recurring issues. Here’s how to avoid common pitfalls:

• Don’t replace the BCM/LCM without confirming all wiring and lamp assemblies are fault-free
• Never overlook aftermarket installations—improperly tapped wires are a frequent cause
• Always inspect the inside of lamp sockets for moisture, which can cause intermittent or persistent shorts
• Use the correct wiring diagrams and pinout references for your exact model and year
• Test with a multimeter, not just a test light, to accurately detect voltage presence and shorts

Express FAQ — B2491 #

Q: Can a faulty bulb alone trigger this code?
A: Yes, if the bulb’s internal filament shorts or if an LED assembly fails internally, it can send voltage back through the circuit, causing a short-to-battery condition.

Q: Will disconnecting the battery clear the code?
A: No, disconnecting the battery may temporarily clear the code from memory, but the underlying issue remains. Only a proper repair will prevent the code from returning.