Code Definition

B1831 — Door Unlock Disarm Switch Circuit Open

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

About B1831

B1831 is a manufacturer-specific body diagnostic trouble code recorded for Ford vehicles. It belongs to the B-prefix family of codes, which covers body, interior, airbag, or comfort-electronics faults.

When B1831 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.

B1831 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

DTC B1831 is set when the Body Control Module (BCM) detects an open circuit in the Door Unlock Disarm Switch input on Ford vehicles equipped with the Passive Anti-Theft System (PATS). This switch, integrated into the driver door key lock cylinder assembly, signals the BCM to disarm the alarm when the cylinder is rotated to the unlock position. An open circuit fault means the BCM is no longer seeing valid resistance or continuity through the disarm switch wiring, the switch itself, or its ground return path. When this code is set the alarm may not disarm via the key cylinder, the key lock unloc...

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