Code Definition

B2503 — RF LAMP LOW BEAM CIRCUIT Failure

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

About B2503

B2503 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 B2503 is stored, the module has detected 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 B2503 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 dedicated front lighting module controls the right front low beam headlamp by switching battery voltage or ground to the bulb, with feedback monitoring to confirm the lamp is operating to specification. DTC B2503 is set when the BCM detects an out of specification condition on the right front low beam circuit, generally when commanded ON the expected current draw or feedback voltage is absent, indicating an open bulb, an open wire, or a high resistance fault in the supply or return path. The BCM logs this code and typically illuminates a lamp out warning on the...

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