B1807 — Lamp Tail Output Circuit Open

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 B1807 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 tail 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 B1807 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for B1807 (parts and labor, USD, independent shop rates): BCM repair or replacement: $300–$900; Replace the switch or actuator: $120–$450; Repair wiring or connectors: $80–$250. Overall, fixing B1807 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 are the symptoms of B1807?

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.

What does OBD2 code B1807 mean?

Lamp Tail Output Circuit Open (B1807): 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, corroded or loose connectors.

How much does it cost to fix B1807?

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

Will B1807 clear itself?

Sometimes B1807 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.

What is the most common cause of B1807?

The most common causes are: blown fuse or failed relay, damaged wiring in door jambs or wet areas, corroded or loose connectors.

When your check engine light or body control warning pops up and a scan tool shows B1807, you're looking at a specific fault in your vehicle's rear lighting circuit. Code B1807 refers to an open condition in the lamp tail output circuit — essentially, the electrical path that feeds power to your tail lights has been interrupted somewhere. The body control module expects to see current flowing through this circuit when the taillights are commanded on, but instead it finds a break in the path and logs the failure.

How does this system work? Your vehicle's body control module manages exterior lighting by providing a ground path for the tail lamp circuit. When you turn on your headlights or activate the taillights, the module completes the circuit by grounding it, allowing current to flow and illuminate the bulbs. The BCM constantly monitors this circuit through feedback signals. If it commands the taillights on but never sees the expected voltage drop indicating current flow, it knows something is broken between the module and the lamp. After confirming this condition across multiple ignition cycles to rule out temporary glitches, the module stores B1807 along with a freeze frame snapshot — engine RPM, vehicle speed, load and coolant temperature recorded at the exact moment the fault was detected.

Understanding that freeze frame data matters. It tells you what conditions existed when the module first spotted the problem, which helps you reproduce the failure during diagnosis rather than chasing a fault that only occurs under specific circumstances.

Common Symptoms of B1807

The most obvious sign of B1807 is your tail lights refusing to illuminate when activated, or working only intermittently depending on road conditions and vehicle vibration. Beyond the lighting issue itself, you may notice a dashboard warning light related to body systems or exterior lighting illuminated. In most vehicles, B1807 does not affect engine performance or drivability — your car will run and drive normally aside from the missing rear lighting. Some vehicles may trigger additional body control codes if the underlying wiring problem affects multiple circuits sharing the same path.

What Causes B1807?

The root cause behind B1807 is always an open circuit — somewhere the 12-volt path from the BCM to the tail lamps is broken. The most frequent culprits are connectors that have become unplugged, pushed back partially, or corroded enough to prevent reliable electrical contact. Wires themselves fail too, especially at stress points where they bend repeatedly through door hinges and tailgate openings. These flex points experience constant movement and eventually the copper strands break, creating an intermittent or complete open. Blown fuses protecting the tail lamp circuit will obviously stop current flow entirely. Less commonly, the switch or actuator controlling the affected function has failed internally. In rare cases, the body control module itself has developed an internal fault preventing it from properly controlling the circuit output.

How to Diagnose B1807

Start by connecting an OBD2 scanner and retrieving all stored codes along with the freeze frame data associated with B1807. Write down those freeze frame parameters — they'll guide your inspection by showing exactly what conditions existed when the module first recorded the failure. Check for any related trouble codes in the B0xxx range that might point toward a shared cause, such as issues with adjacent lighting circuits. Pull up any manufacturer technical service bulletins for your specific make, model and year — many body electrical codes have documented factory fixes or software recalibrations available through the manufacturer website or NHTSA database.

Next, perform a thorough visual inspection of all wiring and connectors in the tail lamp circuit. Look for damaged insulation, chafing from rubbing against metal edges, corrosion buildup on connector pins and obvious wire breaks. Use a multimeter to check for continuity end-to-end on the affected circuit. With the taillight circuit disconnected at both ends, verify that electricity can flow uninterrupted from the BCM output through the entire harness to the lamp ground. While monitoring the multimeter reading, gently wiggle the wiring harness — particularly at door jambs and hinge areas where flexing occurs. An intermittent open will show up as fluctuating resistance readings during this test.

Finally, clear the code and complete a full drive cycle that recreates the conditions shown in your freeze frame data. Run the test until the module completes its verification cycles, then rescan to confirm B1807 does not return.

Repair Options and Costs for B1807

The repair needed depends entirely on what your diagnosis uncovers. If you find corroded connectors, cleaning and resealing them costs only connector replacement pricing if damage is severe — typically $15 to $40 per connector. Wiring repairs involving splicing and sealing a broken wire run $80 to $150 depending on access difficulty. Replacing a failed switch or actuator controlling the tail function costs $120 to $450 when parts and labor are combined at independent shop rates. If the body control module itself has failed internally, BCM replacement or repair runs $300 to $900 including programming and calibration.

How Much Does Fixing B1807 Cost?

Overall repair costs for B1807 range between $80 and $900 depending on which component failed. The cheapest scenarios involve simple wiring repairs or connector cleaning, while BCM replacement represents the most expensive outcome. Labor rates vary by region and shop, but the figures above reflect typical independent shop pricing in the United States. Spending time on accurate diagnosis before purchasing parts almost always saves money — the most expensive repair is rarely the first thing to check.

Can You Drive with B1807?

B1807 presents minimal safety risk in most driving situations. Since the code lives in the body control system, your engine will operate normally and you won't experience drivability problems. The practical concern is reduced visibility to other drivers at night or in poor weather when your tail lights aren't functioning. Address this code within a reasonable timeframe, but you can continue driving until you arrange repairs.