Code Definition

B1801 — Lamp Turn Signal Front Output Circuit Short To Ground

System: Body  |  Type: Manufacturer-Specific  |  Make: Generic

About B1801

B1801 is a manufacturer-specific body diagnostic trouble code. It belongs to the B-prefix family of codes, which covers body, interior, airbag, or comfort-electronics faults.

When B1801 is stored, the module has detected a short-circuit (voltage pulled to ground or to supply) in the monitored circuit.

Scanning & clearing: Body (B) codes are often stored in the body control module, airbag module, or climate module. A basic OBD-II tool usually will not read body codes — an enhanced or OEM-level scan tool is typically required.

B1801 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

The body control module monitors the front turn signal lamp output circuit by measuring voltage and current flow through its lamp output driver. DTC B1801 sets when the module detects the front turn signal output has been pulled to ground potential while the driver is commanded on, or when excessive current through the output stage indicates the circuit is shorted to ground. The module drives the front turn signal lamp through a protected solid state output stage with built in short circuit detection, so a grounded circuit causes the driver to shut down and latch off to protect itself. When th...

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