Code Definition

B2598 — Headlamp Relay Circuit Failure

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

About B2598

B2598 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 B2598 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.

Because B2598 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 B2598 fault code is set when the Body Control Module (BCM) detects a generic circuit failure on the headlamp relay control output. The BCM controls headlamp activation by driving the relay coil that supplies power to the low beam or high beam lamps, and it monitors the output for the correct voltage swing during commanded operation. When the response is out of range, indicating an open circuit, an unexpected voltage, or no feedback during commanded operation, this code is set. The driver may notice headlamps that do not illuminate when commanded, headlamps that stay on after the switch is ...

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