Code Definition

B1802 — Lamp Turn Signal Rear Output Circuit Failure

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

About B1802

B1802 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 B1802 is stored, the module has detected an electrical-circuit fault in the wiring, connector, or driver associated with the named component.

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.

B1802 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 (BCM) controls the rear turn signal lamp output and monitors the circuit for proper operation by measuring current draw and feedback voltage when the lamp is commanded on. DTC B1802 sets when the BCM detects an electrical fault on the rear turn signal output, such as an open circuit, short to ground, or short to battery, that prevents the lamp from operating within expected parameters. On many vehicles the rear turn signal shares the bulb housing with the brake or tail lamp, either as a separate filament in a multi function bulb or as a separately driven LED segment, an...

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