Code Definition

B2478 — Anti Theft Input Signal Short to Ground

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

About B2478

B2478 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 B2478 is stored, the module has detected a short-circuit (voltage pulled to ground or to supply) 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.

Because B2478 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 anti theft module monitors the anti theft input signal which is supplied by sensors such as the hood ajar switch, glass break sensor, interior motion sensor, or aftermarket security sensors fed into the factory anti theft network. DTC B2478 sets when the BCM detects that the anti theft input wire is shorted to chassis ground, holding the input continuously low rather than only signaling when a security event occurs. When this code is active the alarm system may trigger spontaneously, fail to arm correctly, or refuse to arm at all, and the security indicator may...

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