Code Definition

B2504 — RF LAMP LOW BEAM CIRCUIT Short to Battery

System: Body  |  Type: Generic (OBD-II Standard)  |  Make: Generic

About B2504

B2504 is a generic (obd-ii standard) body diagnostic trouble code. It belongs to the B-prefix family of codes, which covers body, interior, airbag, or comfort-electronics faults.

When B2504 is stored, the module has detected a short-circuit (voltage pulled to ground or to supply) in the monitored circuit; and a signal or supply voltage lower than the expected operating range.

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.

Because B2504 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

The Body Control Module (BCM) or front lighting module controls the right front low beam headlamp by switching battery voltage or ground to the bulb. DTC B2504 is set when the BCM detects that the right front low beam control line is shorted to battery voltage, meaning the wire is held at or near system voltage when the BCM is commanding the output OFF. The BCM monitors feedback on the output line to verify its own driver state; when external voltage is forcing the line high, the BCM disables the driver to prevent damage and stores this code. With this fault present the right low beam may stay...

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