Code Definition

B1566 — Door Ajar Circuit Short To Ground

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

About B1566

B1566 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 B1566 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.

B1566 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

B1566 indicates that the Body Control Module (BCM) has detected a short to ground on the door ajar input line. The door ajar switch normally pulls this line to ground when the door is open, and the BCM input floats high through its internal pull up when the door is closed. When the BCM sees the input held at ground regardless of door position, it sets B1566 because the line is no longer presenting a valid open or closed signal. The fault is most often a mechanically stuck switch, a chafed wire shorting against the chassis, or a contaminated connector bridging the signal pin to an adjacent grou...

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