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

How do I diagnose B1873 myself?

Start with a scan: confirm B1873, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the body electrical system, and verify the suspect component against live data before buying parts.

What does OBD2 code B1873 mean?

Turn Signal / Hazard Power Feed Circuit Short To Ground (B1873): a body electrical fault affecting the body electrical system. The car is usually drivable while you plan the repair. Most often caused by blown fuse or failed relay, damaged wiring in door jambs or wet areas, body control module (BCM) fault.

How much does it cost to fix B1873?

BCM repair or replacement — $300–$900; Repair wiring or connectors — $80–$250; Replace the switch or actuator — $120–$450. Exact cost depends on the root cause, your vehicle and local labor rates — a proper diagnosis is the cheapest first step.

What are the symptoms of B1873?

Drivers most often notice: the affected function (locks, windows, lighting, wipers) works intermittently or not at all, warning light on the dashboard, no impact on engine operation in most cases.

Will B1873 clear itself?

Sometimes B1873 clears after a few drive cycles if the fault was intermittent — for example a loose connector or a tank of bad fuel. The underlying cause usually remains, so the code tends to return. Clear it once; if it comes back, diagnose rather than erase it repeatedly.

When the engine control module detects an abnormal condition in your vehicle's body electrical system, it logs a specific fault code to help technicians pinpoint the problem. Code B1873 specifically indicates a short-to-ground fault on the turn signal or hazard warning power feed circuit. This code falls within the body electrical category of OBD2 trouble codes, which means the issue lives in the circuits that power lights, locks, windows, wipers, and other comfort or convenience features rather than in the engine or transmission.

To understand why the module sets B1873, you need to know how modern vehicle electronics work. The body control module continuously monitors voltage and current flow through each circuit it manages. When you activate your turn signals or hazard lights, the module expects to see a specific pattern of power draw. If it detects that a circuit is pulling current when it shouldn't—such as when the circuit has shorted directly to ground—the module identifies the abnormality and stores B1873. Most manufacturers require this condition to repeat across multiple drive cycles before illuminating the check engine light, which explains why intermittent faults sometimes take days to trigger a persistent warning. The stored freeze frame data captures engine RPM, load percentage, coolant temperature, and vehicle speed at the exact moment the fault occurred, giving you valuable context for diagnosis.

The turn signal and hazard light systems share common wiring pathways in most vehicles. Your turn signals operate through a multi-function stalk switch on the steering column, while hazard lights engage through a separate dedicated switch, usually on the dashboard. Both routes ultimately feed power through the body control module or a similar central junction. When B1873 appears, it means the module has identified one of these shared power feeds as being improperly connected to ground somewhere along the circuit. This could stem from damaged insulation on a wire rubbing against metal, water intrusion at a connector, or a failed component drawing unexpected current.

Symptoms of B1873

The affected function may stop working entirely or operate only intermittently. Because B1873 relates to turn signals and hazard lights, you might notice your front or rear turn signals failing to flash, or your hazard lights refusing to activate when you press the button. In some cases, only one side of the vehicle is affected, depending on where the short exists within the shared circuit.

A warning indicator may illuminate on your dashboard, typically a dedicated turn signal indicator that stays dark when you attempt to signal, or a general body system warning light depending on your vehicle's design. Pay attention to whether the instrument cluster shows any unusual behavior when you operate the suspect circuit.

Unlike many powertrain codes, B1873 generally does not affect engine performance, transmission operation, or fuel economy. Your vehicle will still drive, shift, and accelerate normally. The engine control module primarily monitors emissions-related systems and critical powertrain functions, so a body electrical fault like this one typically remains isolated to comfort features.

The problem may worsen over time if moisture continues to corrode connectors or if damaged wiring further degrades. What starts as an occasional failure might progress to a complete loss of function. Similarly, a short-to-ground that causes excessive current draw could potentially damage the body control module if left unaddressed.

You might also notice related electrical quirks—interior lights behaving strangely, central locking responding slowly, or other body functions sharing the same circuit acting erratically. Documenting exactly which systems fail and when helps narrow down the fault location during diagnosis.

Common Causes

Damaged or chafed wiring is the most frequent culprit behind B1873. The wire harness running through door jambs experiences constant flexing every time you open and close the doors. Over years of use, the insulation can crack, rub thin, or abrade against metal edges, exposing the copper conductors and allowing them to short against the vehicle body ground.

Water intrusion at electrical connectors causes corrosion that creates unintended paths to ground. Door hinges, tailgate openings, and engine compartment connections are particularly vulnerable to moisture exposure, especially in vehicles frequently parked outdoors or operated in rainy climates.

Blown fuses or failed relays interrupt power delivery to the affected circuit. While a single blown fuse might indicate nothing more than a temporary overload, a fuse that blows repeatedly points toward an underlying short that needs correction.

Loose or corroded connector pins prevent proper electrical contact, leading to voltage drops, intermittent operation, and eventually fault codes like B1873. Connectors in wet environments accumulate corrosion deposits that insulate the metal contacts.

Body control module internal failures can produce B1873 even when all wiring checks out perfectly. The BCM processes inputs from multiple switches and sensors, then commands outputs to various loads. Internal MOSFET failures or circuit board defects within the module itself can generate false fault readings.

Faulty turn signal or hazard light switches sometimes fail in ways that create shorts within the control circuit. The multi-function stalk assembly on the steering column endures significant mechanical stress over its service life and may eventually develop internal faults.

Actuator motors or their associated control circuits can fail in ways that backfeed problems into the shared power bus. While less common than wiring issues, a failed motor windings short can absolutely trigger B1873.

How to Diagnose B1873

Before diving into physical inspection, connect an OBD2 scanner to retrieve all stored codes and freeze frame data. Record the exact conditions when B1873 set—engine RPM, calculated load, coolant temperature, and vehicle speed at the moment of detection. Replicating these exact conditions during your test drive increases the likelihood of triggering the fault during active diagnosis.

Review any other body-related codes present in the system. Codes B1800 through B1805, for instance, relate directly to turn signal circuits and often appear alongside B1873. Multiple related codes pointing to the same system strongly suggest a common failure point, such as a wiring harness issue or a shared power supply problem. Also check for manufacturer technical service bulletins that apply to your specific make, model, and model year—many body electrical faults have known root causes documented by factories with published repair procedures or software updates.

Perform a thorough visual inspection of all accessible wiring and connectors in the turn signal and hazard light circuits. Focus especially on the door jamb areas where harness wires flex constantly, the trunk or tailgate opening where wiring passes through rubber boots, and any connectors you can access without disassembly. Look for scraped insulation, melted wire jackets, greenish corrosion deposits, or connector pins that appear bent, darkened, or loose. Gently tug on each wire at connectors to verify the crimp connections haven't weakened.

Operate the turn signal lever through all its positions while observing the circuit's live data parameters. Most scan tools display switch state, command status, and actual output voltage or current. Watch for inconsistencies between what the switch reports and what the output circuit delivers. A switch that shows "on" but produces no output current indicates a problem downstream of the switch.

Check fuse and relay condition in the applicable circuits. Remove each fuse related to exterior lighting and inspect the element visually. Use a multimeter to verify no unexpected continuity exists between the power side of any fuse and ground when the circuit should be off. Inspect relay operation by swapping with a known-good relay of identical type, or test coil and contact resistance with your multimeter.

After completing repairs, clear the stored code and perform a complete drive cycle that includes activating the turn signals and hazard lights multiple times. Return to the scanner and verify B1873 does not reappear. If the code returns, continue troubleshooting—you haven't found the root cause yet.

Repair Options and Costs

Wiring repair represents the most economical solution when damage is localized. If inspection reveals chafed wires in a door jamb or corroded pins at a connector, a skilled technician can splice in new wire sections, clean or replace the affected connector, and apply protective coatings for approximately $80 to $250 depending on accessibility and labor time required. DIY-conscious owners with basic electrical skills can often perform simple repairs using heat-shrink butt connectors, dielectric grease, and electrical tape at minimal parts cost.

Connector replacement becomes necessary when corrosion has destroyed the terminals inside. New connectors with weatherproof seals typically run $15 to $40 each, though professional installation labor varies by location and complexity. Budget $120 to $250 total for connector replacement when multiple damaged connectors exist.

Turn signal switch replacement on the steering column involves steering wheel removal and column disassembly. Parts alone range from $50 to $200 depending on vehicle make, with labor adding $150 to $300 for the approximately two hours of work involved. Total switch replacement typically costs $120 to $450.

Body control module repair through a specialized electronics shop can save money compared to dealer replacement. BCM board repair, including replacing failed MOSFETs or solder joints, generally costs $300 to $500. Full module replacement with a new or refurbished unit from a dealer runs $500 to $900 including programming and coding to the vehicle.

Driving Safety Verdict

Severity level: short. B1873 does not impair your vehicle's ability to drive, stop, or steer. You can safely operate the car to a repair facility or your own garage without concern for mechanical consequences. That said, driving without functioning turn signals significantly compromises road safety—other drivers cannot anticipate your lane changes or turns, increasing collision risk. If your hazard lights fail, you lose the ability to warn other road users during a breakdown or emergency. Address this code within a reasonable timeframe, but it does not require immediate roadside repair or towing.

Related OBD2 Codes

• B1800: Lamp Turn Signal Front Output Circuit Short To Battery
• B1801: Lamp Turn Signal Front Output Circuit Short To Ground
• B1802: Lamp Turn Signal Rear Output Circuit Failure
• B1803: Lamp Turn Signal Rear Output Circuit Open
• B1804: Lamp Turn Signal Rear Output Circuit Short To Battery
• B1805: Lamp Turn Signal Rear Output Circuit Short To Ground

The B1873 OBD2 fault code relates to the Turn Signal / Hazard Power Feed circuit. When the circuit circuit failure, the module cannot properly monitor or control this body system.

At AIscanAuto, we help drivers quickly identify OBD2 trouble codes, understand their root causes, and find the right fix.

Symptoms

• Light not working (headlamp, turn signal, tail, or interior)
• Possible bulb warning on dashboard
• Dim or flickering lights
• Other related lamps affected

Common Causes

• Faulty component — internal damage or wear affecting Turn Signal / Hazard Power Feed
• Wiring issues — broken, corroded, or chafed wires in the circuit
• Connector problems — loose, oxidized, or moisture-damaged pins
• a general circuit failure is detected — can result from wiring faults, connector issues, or component failure
• Module input failure — rare, but the control module input stage may be defective

Step-by-Step Diagnosis

1. Scan with OBD2 tool — Confirm B1873 is active. Check for additional DTCs.
2. Visual inspection — Examine the Turn Signal / Hazard Power Feed wiring and connector for corrosion or damage.
3. Check voltage and ground — Use a multimeter to verify proper reference voltage.
4. Test component — Compare readings to factory specs. A stuck or erratic signal confirms failure.
5. Check for shorts/opens — Perform continuity tests on the wiring between the component and control module.

Repair & Solutions

• If the component is defective, replace the Turn Signal / Hazard Power Feed with an OEM or quality aftermarket part.
• Repair any damaged wiring or connectors using proper methods.
• Clear the DTC with an OBD2 scanner and test drive to verify the code does not return.
• If the code persists after component replacement, inspect the control module connector.

Related Codes

• B1870 — Lamp Air Bag Warning Indicator Circuit Short To Battery
• B1871 — Passenger Air Bag Disable Module Fault
• B1872 — Turn Signal / Hazard Power Feed Circuit Short To Battery