B1873 — Turn Signal / Hazard Power Feed Circuit Short To Ground #

Note: The code description may vary depending on the vehicle manufacturer. Always refer to your OEM (Original Equipment Manufacturer) documentation for the most accurate information.

• Turn Signal/Hazard Power Feed Circuit Shorted to Ground (Ford)
• Turn Signal or Hazard Feed Circuit Low (GM/Chevrolet)
• Indicator/Hazard Power Supply Shorted to Ground (Toyota)
• Flasher Power Feed Circuit Short to Ground (Chrysler)

Summary of Code B1873 #

The B1873 diagnostic trouble code (DTC) is set when the vehicle’s body control module (BCM) detects a short to ground in the turn signal or hazard power feed circuit. In simple terms, this means the wiring or component supplying power to your blinkers or hazard lights is touching the vehicle’s grounded metal parts, causing an electrical fault. The code is typically triggered by damaged wiring, faulty switches, or malfunctioning relays that are part of your lighting system. Since proper signaling is crucial for road safety, this code should not be ignored. Understanding the root cause is essential for restoring both function and safety.

Common Symptoms for Code B1873 #

When your vehicle displays a B1873 code, you might notice several issues related to your turn signals or hazard lights. These symptoms can be intermittent or consistent, depending on the severity of the short circuit. Here’s what you might observe:

• Turn signals not working at all
• Hazard lights inoperative
• One or both turn signals stuck on or off
• Rapid or irregular blinking of turn signals
• Blown fuse related to the signal/hazard circuit
• Warning lights or messages on the dashboard

Probable Causes for Code B1873 #

Several underlying issues can cause a short to ground in the turn signal or hazard power feed circuit. The most common causes, starting with the most frequent, are:

1. Damaged or frayed wiring harness touching the vehicle chassis
2. Faulty turn signal switch or hazard switch (internal short)
3. Defective relay or module within the lighting system
4. Corrosion in connectors or terminals leading to unintended grounding
5. Improper aftermarket electrical modifications or installations
6. Moisture intrusion into the fuse box or wiring connectors

Step-by-Step Diagnostics for Code B1873 #

Diagnosing a B1873 code requires a systematic approach to isolate the short. Here’s a proven workflow, whether you’re a DIYer or a technician:

• 1. Confirm the code: Use an OBD-II scanner to verify B1873 and check for any related codes.
• 2. Visual inspection: Examine the wiring from the fuse box to the turn signal/hazard switch for any visible damage, wear, or exposed wires.
• 3. Check the fuses: Inspect and, if necessary, replace any blown fuses in the signal/hazard circuit.
• 4. Test switches: Operate the turn signal and hazard switches, noting any erratic behavior or failure.
• 5. Inspect connectors: Look for corrosion, debris, or loose pins in all connectors related to the circuit.
• 6. Perform continuity and ground tests: Using a multimeter, check for continuity to ground where it shouldn’t exist, indicating a short.
• 7. Inspect relays and modules: Swap relays if possible or test with a known good unit, and check for signs of overheating or internal failure.
• 8. Isolate sections: If the short persists, disconnect parts of the circuit (e.g., at the switch, relay, or bulb sockets) to narrow down the faulty area.

Possible Repairs for Code B1873 #

Once the source of the short is identified, repairs will depend on the root cause. Here are common solutions, each linked directly to the causes above:

• Repair or replace damaged wiring harnesses, ensuring proper insulation and routing away from sharp metal edges.
• Replace a faulty turn signal or hazard switch if internal shorts are detected.
• Swap out defective relays or lighting modules as necessary.
• Clean or replace corroded connectors and apply dielectric grease for future protection.
• Remove or properly integrate any aftermarket electrical components that could interfere with OEM wiring.
• Seal or replace connectors affected by moisture to prevent recurring issues.

Is It Safe to Drive with Code B1873? #

Driving with a B1873 code is not recommended. Turn signals and hazard lights are critical for your safety and legal compliance on the road. A short to ground can disable these functions, making your intentions invisible to other drivers and increasing the risk of accidents. If the issue is intermittent, you may have some function, but the risk of sudden failure remains high. Addressing the problem promptly ensures both your safety and that of other road users.

Vehicles Most Commonly Affected by Code B1873 #

While B1873 can occur in any vehicle equipped with advanced body control modules and electronic lighting systems, it is more frequently reported in certain models and brands, often due to specific wiring layouts or design quirks. Vehicles most often affected include:

• Ford F-Series (F-150, F-250, etc.)
• Chevrolet Silverado and GMC Sierra
• Toyota Camry and Corolla (selected years)
• Chrysler Town & Country and Dodge Caravan
• Ford Focus and Fusion
• GM SUVs (Tahoe, Suburban, Yukon)

Common Mistakes & Best Practices for B1873 #

Misdiagnosing or incorrectly repairing a B1873 code can lead to wasted time and repeated failures. Avoid these pitfalls and follow best practices:

• Overlooking simple issues like a blown fuse or corroded connector
• Replacing switches or relays without first inspecting the wiring for shorts
• Neglecting to check for aftermarket alarm or lighting modifications
• Failing to use proper diagnostic tools (multimeter, test light)
• Not verifying repair by clearing the code and confirming proper operation

Express FAQ for Code B1873 #

Here are quick answers to common questions about this trouble code:

• Q: Will B1873 affect my other lighting systems?
  A: Usually, B1873 only affects the turn signal and hazard circuits, but on some models, related circuits may share fuses or relays, causing further issues.
• Q: Can I reset the code and ignore it if my lights work again?
  A: Clearing the code without fixing the underlying problem can lead to a recurrence and possible safety hazards. Always identify and repair the root cause before resetting the code.