B0781

Code

Generic B — Body

Front passenger seat belt buckle switch circuit — open/short

Brand: Generic

Type: B — Body

Views: UK: 5 EN: 10 RU: 7

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Scan vehicle and read all stored and pending SRS/BCM/occupant detection codes and freeze frame data
Verify live data stream for front passenger buckle status while operating the buckle
Perform a visual inspection of buckle, wiring, connectors under seat and at C-pillar area for damage or corrosion
Check for water intrusion or contamination in buckle area
Wiggle test harness with connector plugged while monitoring live data to check intermittent faults
Check connector mating pins for corrosion, bent pins or pushed out terminals

Typical buckle switch open: very high resistance (open circuit) or ECU-reported ‘unbuckled’ state
Typical buckle switch closed: low resistance (near 0–10 Ω across the switch contacts) or ECU-reported ‘buckled’ state
Voltage at switch circuit may be near battery voltage (~12 V) or a reference voltage (often ~5 V) when open, and near ground (
Intermittent wiggle-induced changes in signal indicate wiring or connector fault

Safely disable vehicle power/airbag system per manufacturer procedures before seat removal or connector work
Use a scan tool to confirm B0781 and note any related codes (SRS/BCM/occupant classification)
With connector accessible, inspect pins for corrosion, damage or looseness; repair or replace damaged connector/terminals
Inspect wiring from buckle to module for chafing, breaks, or pinched areas—pay special attention to seat hinge and sliding tracks
Perform continuity test between buckle switch terminal and the module input; expect low resistance when buckle closed and open circuit when unbuckled (verify expected behavior using scan tool live data)
If voltage test is required, backprobe connector with ignition on (or as manufacturer directs) and operate buckle while observing voltage change; compare to expected reference values
If wiring and connectors are good, bench test or replace the seat belt buckle switch assembly and re-check fault codes and live data
Clear codes and conduct road/seat use verification to ensure code does not return; if intermittent, perform repeated buckle cycles and wiggle tests to reproduce
If code persists after repair, consult vehicle-specific wiring diagrams and module inputs for further diagnosis or possible module fault