Code Definition

B1304 — Accessory Delay Relay Coil Circuit Short To Battery

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

About B1304

B1304 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 B1304 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.

B1304 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 Body Control Module (BCM) monitors the accessory delay relay coil circuit, which controls retained accessory power to systems such as power windows, sunroof, and radio for a short period after the ignition is switched off. DTC B1304 is set when the BCM detects unintended battery voltage on the relay coil control wire, indicating a short to battery condition. The BCM normally controls the relay by switching the coil control wire to ground, so when battery voltage is forced onto that wire externally the BCM cannot deactivate the relay even when commanded off. When this code is set, the acces...

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