Code Definition

B1521 — Hood Switch Circuit Short To Battery

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

About B1521

B1521 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 B1521 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.

B1521 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 Hood Switch is a body system input that tells the body control module, central electronic module, or alarm controller whether the hood is open or closed, and forms part of the security and convenience systems on the vehicle. The switch typically operates by grounding a pulled up reference voltage supplied by the controlling module, so the module sees either battery voltage (or a stable reference) when the switch is open, and a near zero voltage when the switch closes the circuit. DTC B1521 is set when the controlling module detects battery voltage on the hood switch signal wire at a time w...

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