Code Definition

B1504 — Lamp Turn Signal Right Circuit Open

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

About B1504

B1504 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 B1504 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.

B1504 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) or lighting control module monitors the right turn signal lamp circuit and uses load feedback or current sensing to verify that the lamps are present and operating. DTC B1504 sets specifically when the module detects an open circuit on the right turn signal output, meaning current is not flowing as expected when the lamp should be illuminated. An open can occur at the bulb itself (filament failure), at any socket, splice, or connector along the harness, or inside the BCM driver. When this code is active the driver typically sees the affected lamp not illuminate, t...

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