GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2009 🢒 Vibe - AWD 🢒 DTC 🢒 DTC B1771

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC B1771: Passenger Seat Belt Sensor Circuit

Circuit/System Description

The seat belt buckle switch circuit consists of a seat belt buckle switch and the sensing and diagnostic module (SDM). The SDM monitors the seat belt buckle switch for a buckled/unbuckled state. If the SDM detects a malfunction within the seat belt buckle switch circuit, a DTC will be set.

Conditions for Running the DTC

Ignition voltage is between 9-16 volts.

Conditions for Setting the DTC

Any of the following conditions exist for 2 seconds:

B1771

    • The passenger seat belt buckle circuit is shorted.
    • The passenger seat belt buckle circuit is open.
    • Passenger seat belt buckle malfunction.
    • Occupant classification module malfunction.

Action Taken When the DTC Sets
    • The SDM commands the AIR BAG indicator ON.
    • The SIR System is disabled and no deployments are allowed.

Conditions for Clearing the DTC
    • The condition for setting the DTC no longer exists.
    • A history DTC will clear once 100 malfunction-free ignition cycles have occurred.

Reference Information

Schematic Reference

SIR Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

SIR System Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Testing for Intermittent Conditions and Poor Connections
    •  Connector Repairs
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information.

Circuit/System Testing

Important: Refer to SIR Service Precautions .

When removing connectors, inspect for damage or corrosion. Damage or corrosion in the following requires repair or replacement of the affected component/connector:

   • The front end sensor
   • The SDM module
   • The front end sensor wiring harness connector
   • The SDM wiring harness connector

  1. Ignition OFF, disconnect the harness connector at the SDM and the appropriate sensor.
  2. Ignition ON, test for less than 1 volt between the signal circuit terminal 13 and ground.
    3. ⇒If greater than the specified range, repair the circuit for a short to voltage.
  3. Ignition ON, test for less than 1 volt between the low reference circuit terminal 14 and ground.
    4. ⇒If greater than the specified range, repair the circuit for a short to voltage.
  4. Test for infinite resistance between the signal circuit terminal 13 and ground.
    5. ⇒If less than infinite resistance, repair the circuit for a short to ground.
  5. Test for less than 1 ohm between front inner seat belt assembly - passenger terminal 2 and SDM harness connector terminal 13.
    6. ⇒If greater than the specified range, repair the circuit for an open/high resistance.
  6. Test for less then 1 ohm between front inner seat belt assembly - passenger terminal 1 and SDM harness connector terminal 14.
    7. ⇒If greater than the specified range, repair the circuit for an open/high resistance.
  7. If all circuits test normal, replace the passenger seat belt buckle assembly.
  8. Reconnect all SIR components. Ignition ON, with a scan tool clear and check for DTCs.
    9. ⇒If the DTC returns and is current, replace the occupant classification module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Inflatable Restraint Front End Sensor Replacement
    •  Inflatable Restraint Side Impact Sensor Replacement
    •  SIR/SRS Wiring Repairs
    •  Control Module References for SDM replacement, setup, and programming