B3772

Code

Generic B — Body

Seat Position Sensor 'A' Circuit High

Brand: Generic

Type: B — Body

Views: UK: 12 EN: 14 RU: 17

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Short to battery voltage on the seat position sensor signal or supply wire
Faulty seat position sensor (internal failure)
Open or damaged wiring that causes sensor output to float high
Corroded, loose or damaged connector pins at the sensor or module
Faulty occupant classification/airbag control module or wiring inside the module
Water intrusion or contamination at the seat connector or sensor

Symptoms

Airbag/airbag warning light or occupant classification warning lamp illuminated
Seat memory or seat adjustment faults (if equipped)
Possible inability for restraint system to correctly classify occupant
Stored fault code B3772 and possibly related B-codes
Intermittent faults when moving the seat or occupants shift

What to check

Scan for DTCs and record freeze frame / live data for seat position sensor 'A'
Visual inspection of seat wiring, connector, and sensor for damage, corrosion or moisture
Wiggle test the seat harness and observe live data or fault response
Backprobe the sensor connector while monitoring voltage with key ON (engine off)
Verify reference voltage (typically ~5 V) and ground at the sensor connector
Measure sensor output voltage while moving the seat (if mechanical) or changing sensor position

Signal parameters

Expected reference supply: ~5.0 V (varies by manufacturer)
Expected sensor output: typically within ~0.2–4.8 V during normal range (manufacturer-specific)
Circuit high condition: sensor output significantly above normal max (often >4.8–5.0 V) or near battery voltage
Open/float symptoms: output may read high if internal pull-up in module is present (consult OEM data)

Diagnostic algorithm

Read and record all stored codes and freeze frame data. Note whether other SRS/occupant classification codes are present.
Visually inspect the seat underside, harness routing, and connectors for damage, corrosion, water, or pinch points. Repair or protect any damaged wiring.
With ignition ON (engine OFF), backprobe the sensor connector: verify reference voltage (≈5 V) and ground presence. If reference is absent or incorrect, trace to control module.
Measure the sensor output voltage at the connector. If output is above the expected range (near battery voltage), check for short to B+ on the wiring between the sensor and module.
Wiggle the harness and connectors while monitoring live data or voltage to look for intermittent shorts or opens. Move the seat through its range if applicable.
Disconnect the sensor and observe module response: some modules will register open or a default value — compare behavior to manufacturer expectations. If voltage remains high with sensor disconnected, suspect wiring short or module fault.
Perform continuity and resistance checks: measure resistance between the sensor signal pin and battery + to confirm any short, and between signal pin and module input to confirm harness continuity. Repair/replace wiring as needed.
If wiring and connectors check good, bench-test or replace the seat position sensor. Reconnect and retest.
If fault persists after sensor and harness repairs, consider control module input fault — consult OEM service manual for module bench tests or replacement procedure.
After repairs, clear codes and verify repairs by rechecking live data and ensuring the code does not return under normal operation and seat movement.