Code Definition

B1303 — Accessory Delay Relay Coil Circuit Open

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

About B1303

B1303 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 B1303 is stored, the module has detected an open (broken or disconnected) electrical path 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.

B1303 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 B1303 is set specifically when the BCM detects an open circuit on the relay coil control wire, meaning it cannot complete the ground path needed to energize the relay coil. The open circuit may exist within the coil winding itself, in the wiring between the BCM and the relay, or at the relay socket terminals. When this code is set, the accessory delay function is dis...

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