B1799 — Lamp Turn Signal Front Output Circuit Open

B1799 — Lamp Turn Signal Front Output Circuit Open. A fault in the body electrical system. The car is usually drivable while you plan the repair. Typical causes: faulty switch, motor or actuator of the affected system, damaged wiring in door jambs or wet areas, blown fuse or failed relay.

body electrical

Is it safe to drive?

Short-term driving is OK Usually safe to drive — body codes rarely affect drivability. Exceptions: exterior lighting and wipers in bad weather, and central locking faults that can leave the car unsecured.

How to diagnose with an OBD scanner

Read the code and freeze frame Connect an OBD2 scanner, confirm B1799 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
Check for companion codes and TSBs Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many B0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
Inspect wiring and connectors Visually inspect the wiring harness and connectors related to the body electrical system for damage, corrosion, chafing or poor contact.
Subsystem check Do a continuity test end-to-end on the lamp turn signal front output circuit and wiggle the harness while measuring — intermittent opens show up as fluctuating readings.
Subsystem check Operate the affected function while watching its switch and motor PIDs in live data.
Subsystem check Inspect connectors and wiring at flex points (door jambs, tailgate hinges) — wires break there first.
Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm B1799 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for B1799 (parts and labor, USD, independent shop rates): Repair wiring or connectors: $80–$250; Replace the switch or actuator: $120–$450; BCM repair or replacement: $300–$900. Overall, fixing B1799 usually costs between $80 and $900. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Common questions

What does OBD2 code B1799 mean?

What is the most common cause of B1799?

The most common causes are: faulty switch, motor or actuator of the affected system, damaged wiring in door jambs or wet areas, blown fuse or failed relay.

Is it safe to drive with B1799?

Usually safe to drive — body codes rarely affect drivability. Exceptions: exterior lighting and wipers in bad weather, and central locking faults that can leave the car unsecured.

What are the symptoms of B1799?

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

Will B1799 clear itself?

Sometimes B1799 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 your vehicle's control module detects a broken electrical path in the front turn signal circuit, it logs trouble code B1799. This code sits in the body electrical category, which means the problem lives in the lighting, door locks, windows, or similar comfort and convenience systems rather than the engine itself. In plain language, B1799 tells you the front turn signal output circuit has an open — current cannot flow through it the way the module expects.

The module does not set B1799 based on a single bad reading. It watches the circuit over time and confirms the fault under specific conditions before triggering the warning light and storing the code. The freeze frame data that accompanies B1799 records engine load, RPM, coolant temperature, and vehicle speed at the exact moment the problem appeared. You can use that snapshot to reproduce the conditions on a test drive and watch the fault reappear.

An open circuit simply means the electrical loop is broken somewhere between the module and the component. Common culprits include a cut or chafed wire, a connector that is unplugged or so corroded that metal no longer touches metal, a blown fuse, or a turn signal assembly with an internal failure. Tracing that path methodically is the entire job.

Symptoms of B1799

The check engine light or body control warning lamp may illuminate on the dashboard
The front turn signal on one or both sides fails to flash, or flashes only intermittently
Other body electrical functions — related windows, locks, or wipers — operate erratically or stop completely
No noticeable change to engine performance, throttle response, or fuel economy
The fault may appear and disappear depending on road conditions or temperature

Common Causes of B1799

A broken or severed wire in the front turn signal output harness
A connector that is unplugged, has a backing pin, or shows heavy corrosion on its terminals
An internally failed front turn signal bulb socket or lamp assembly
A blown fuse protecting the affected body circuit
Wiring damaged at flex points — door hinges, hood seams, or trunk lids are the usual spots
Corroded or loose ground connections feeding the circuit
A faulty turn signal switch or associated actuator motor

How to Diagnose B1799

Plug in an OBD2 scanner, read stored codes, and capture the freeze frame data for B1799. That snapshot tells you exactly what the engine was doing when the module detected the fault.
Check for any other body-related trouble codes at the same time. A pattern of B0xxx codes often points to a shared ground or a single connector that, once repaired, clears several codes at once.
Visually inspect the front turn signal harness and connectors. Look for cracked insulation, rubbed-through wires, moisture intrusion, and any signs of corrosion or heat damage.
Perform a continuity test on the entire front turn signal output circuit from the module to the lamp. Wiggle the harness during the test — a damaged wire that only opens under movement will show up as a fluctuating meter reading.
Use your scanner to monitor live data for the turn signal switch and lamp operation while you activate the stalk. Watch for PID values that stutter or drop out.
Examine connectors and wiring at all flex points, especially the driver-side door jamb where wires pass through a boot that flexes every time the door opens and closes.
Clear B1799, complete a full drive cycle that reproduces the freeze frame conditions, and verify the code does not come back before declaring the repair complete.

Repair Options and Costs

The right fix depends entirely on which part of the circuit failed. B1799 is one of those codes where the most obvious-sounding repair is rarely the most expensive one, so work through the cheap possibilities first.

Wiring repair or connector terminal replacement by an independent shop typically runs $80 to $250, depending on access and whether the harness must be removed from the vehicle.
Replacing a faulty turn signal switch, actuator motor, or the front lamp assembly itself generally costs $120 to $450, including parts and labor.
If the body control module itself is at fault, BCM repair or replacement ranges from $300 to $900, depending on whether the unit can be rebuilt or must be sourced new and programmed.

Total Cost to Fix B1799

For most vehicles, the total bill for B1799 falls between $80 and $900. In the majority of cases, the problem turns out to be a damaged wire or a corroded connector — well under $300 to repair. BCM replacement is the least common cause and represents the worst-case scenario. Spending time on careful diagnosis before buying parts almost always costs less than replacing components that were not actually broken.

Can You Drive with B1799?

Yes — in most cases B1799 does not affect engine operation, transmission function, or braking. The vehicle remains fully drivable. The practical concern is safety: a non-functional front turn signal reduces your ability to signal lane changes and turns to other drivers, which is a hazard in traffic and a potential inspection failure. If the fault also affects wipers or central locking, address those promptly as well. Otherwise, you can schedule the repair at your convenience without risking a breakdown.