B1801: Lamp Turn Signal Front Output Circuit Short to Ground
3 vehicles · 1 makes · $250-$900 repair
Most Reported On
B1801 is an OBD-II diagnostic trouble code meaning “Lamp Turn Signal Front Output Circuit Short to Ground.” B1801 is a manufacturer-specific body code (most commonly seen on Ford and related makes) indicating the lighting control module detected a short to ground on the front turn-signal lamp output circuit. The module monitors the current it sends to the bulb and flags a fault when that circuit is pulled to ground instead of behaving normally. On other manufacturers this exact code string can mean something different, so the definition should be confirmed against the specific make. The practical effect is usually an inoperative or improperly behaving front turn signal. This code is most commonly reported on 2009-2013 Toyota Corolla, 2006-2012 Toyota RAV4, and 2005-2015 Toyota Tacoma, with repair costs ranging from $250 to $900.
Common Causes
Typical Repair Cost
Based on 3 documented vehicle-specific issues. Actual cost depends on root cause and vehicle.
Diagnostic Tools
To diagnose B1801, you'll need an OBD-II scanner. Here are our recommendations at every price point.
ANCEL AD310 Classic OBD-II Scanner
by ANCEL
A simple, affordable code reader that reads and clears check engine codes. Great for quick diagnostics on any OBD-II vehicle (1996+).
- Read & clear engine codes
- View freeze frame data
- I/M readiness status
- No batteries or app needed
BlueDriver Pro Bluetooth Scanner
by BlueDriver
Bluetooth OBD-II scanner with a free companion app. Provides enhanced diagnostics, smog readiness, and repair reports sourced from a database of verified fixes.
- Enhanced diagnostics (ABS, SRS, transmission)
- Repair Reports with verified fixes
- Smog check readiness
- Free app (iOS & Android)
LAUNCH CRP123X OBD-II Scanner
by LAUNCH
A professional-grade handheld scanner that reads all four major systems (engine, transmission, ABS, SRS) with live data streaming and graphing.
- Engine, transmission, ABS, SRS diagnostics
- Live data stream & graphing
- AutoVIN for vehicle identification
- Free lifetime updates via Wi-Fi
Autel MaxiCOM MK808S Diagnostic Tool
by Autel
Shop-level diagnostic tablet with bi-directional control, active tests, and full system coverage. Ideal for serious DIYers and small shops.
- All-system diagnostics (25+ modules)
- Bi-directional control & active tests
- Oil reset, EPB, BMS, TPMS, injector coding
- 7-inch touchscreen with Android OS
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Vehicles Affected (3)
Airbag Warning Light from Spiral Cable (Clock Spring) Failure
Steering Column Spiral Cable Failure Causing Airbag/SRS Light and Loss of Horn or Wheel Controls
Spiral Cable / Clock Spring Failure Triggering Airbag Light and Inoperative Steering Wheel Controls
FAQ
What does B1801 mean?
B1801 stands for "Lamp Turn Signal Front Output Circuit Short to Ground." B1801 is a manufacturer-specific body code (most commonly seen on Ford and related makes) indicating the lighting control module detected a short to ground on the front turn-signal lamp output circuit. The module monitors the current it sends to the bulb and flags a fault when that circuit is pulled to ground instead of behaving normally. On other manufacturers this exact code string can mean something different, so the definition should be confirmed against the specific make. The practical effect is usually an inoperative or improperly behaving front turn signal.
What are the most common causes of B1801?
The most common causes of B1801 are: Short to ground in the front turn-signal wiring, Chafed or pinched harness near the front lamp, Corroded or damaged bulb socket/connector, Faulty turn-signal bulb, Water intrusion in the front lamp assembly, Internal fault in the lighting/body control module. The specific cause varies by vehicle.
How much does it cost to fix B1801?
Repair costs for B1801 range from $250 to $900, depending on the vehicle and root cause.
Which vehicles are affected by B1801?
Au7o has documented B1801 across 3 vehicle models from 1 manufacturers: Toyota.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.