Code Definition

B1877 — Seatbelt Driver Pretensioner Circuit Open

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

About B1877

B1877 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 B1877 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.

B1877 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

B1877 is set by the Restraints Control Module (RCM) when it detects a confirmed open circuit in the driver side seat belt pretensioner squib loop during its continuous SRS self test. Unlike a general circuit failure code, this fault specifically points to broken continuity in the wiring or pretensioner squib rather than a short or resistance value at the high end of the acceptable window. The pretensioner is a pyrotechnic device built into the driver seat belt retractor or buckle that fires during a collision to remove slack from the belt and hold the occupant in position for proper airbag int...

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