Code Definition

B1799 — Lamp Turn Signal Front Output Circuit Open

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

About B1799

B1799 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 B1799 is stored, the module has detected an open (broken or disconnected) electrical path 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.

B1799 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 front turn signal lamp output and monitors the circuit for proper current flow when the lamp is commanded on. DTC B1799 sets when the BCM detects an open circuit specifically on the front turn signal output, meaning current cannot flow through the load when the lamp is commanded by the turn signal stalk or hazard switch. The detection is typically based on missing return current, an output line that fails to pull down to ground when commanded, or a feedback voltage that remains at supply potential rather than dropping across the lamp load. When this c...

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