B2783

Code

HUMMER B — Body

Occupant Presence Sensor Circuit Fault

Brand: HUMMER

Type: B — Body

Views: UK: 14 EN: 22 RU: 10

AI status

Completed

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Page language: EN

Causes

Open or shorted wiring between sensor and airbag/occupant classification module
Poor or corroded connector(s) at the seat sensor or module
Failed occupant presence sensor (FSR/pressure mat) or occupant classification module
Water/moisture intrusion or physical damage to the seat cushion/sensor
Intermittent connection from damaged seat harness (seatbelt buckle, seat track area)
Software/ECU communication fault or bad module ground

Symptoms

Passenger airbag indicator may stay on or off incorrectly
Airbag readiness light (SRS) ON or DTC lamp illuminated on dash
Passenger airbag disabled when seat is occupied, or enabled when seat is empty
Vehicle stores additional B- or U-codes related to SRS or seat modules
Intermittent airbag/occupant status messages

What to check

Read all stored codes and freeze frame data with a capable scan tool that can access SRS/occupant classification systems
Record when code set (ignition status, seat occupancy) and any other related codes
Perform a visual inspection of the passenger seat: connectors, visible wiring, seat cushion condition and signs of moisture/damage
Check connector retention and pin condition at the occupant classification module and sensor(s) under the seat
Attempt to reproduce fault by sitting in different positions and note occupant status indications

Signal parameters

Reference voltage typically ~5 V (sensor supply) with signal varying between ~0–5 V depending on sensor type (verify exact values from vehicle wiring diagram)
Seat mat/FSR resistance will change with load — expect a measurable change when applying weight (model-dependent)
CAN/LIN messaging: occupant classification modules may report occupancy status over vehicle network; expected messages present when system healthy
Open-circuit: infinite resistance between sensor signal and module; short-to-ground: ~0 V at signal; short-to-battery: ~battery voltage at signal

Diagnostic algorithm

Connect an OEM-capable scan tool. Read and record B2783 and any related SRS or network codes and freeze frame data.
Verify current occupant status reported by the scan tool with the passenger seat empty and with a test passenger. Note inconsistencies.
Visually inspect seat cushion, seams, and underside for moisture, corrosion, or physical damage. Inspect connectors and routing through the seat and into the floor/centre console for chafing or pinches.
With ignition ON (engine off), backprobe the sensor connector and measure reference voltage, signal voltage, and ground at the sensor harness. Compare to expected values from the service manual. Observe signal while applying weight to the seat.
Check continuity and resistance of the sensor circuit between the sensor connector and occupant classification module; look for opens/shorts. Wiggle harness and seat while watching live data/voltage for intermittent faults.
If wiring and connectors test good but signal is out of range, disconnect sensor and verify open-circuit behaviour and expected resistance values across sensor terminals (refer to service manual for exact resistances).
If sensor is faulty, replace occupant presence sensor (seat mat) or module per manufacturer procedure. If module suspected, follow module replacement and initialization/qualification procedures.
After repairs, clear codes and perform occupant sensor calibration/initialization if required by the manufacturer. Retest for proper operation and re-check for stored codes.
If intermittent or network communication faults persist, inspect CAN/LIN wiring and module grounds; consult wiring diagrams and consider module swap only after confirming harness integrity.

Likely causes

Corroded/loose connector at the seat sensor or classification module
Damaged wiring harness in seat (pinch point at seat rail or hinge)
Failed occupant presence sensor element (pressure mat)

Fault status

⚠️ Status

Detected open/short/out-of-range or communication error on occupant presence sensor circuit. Possible conditions recorded: open circuit, short to ground, short to battery, intermittent/high resistance, or invalid occupancy data.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-2.5 hours

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B2783 — Occupant Presence Sensor Circuit Fault