GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2006 🢒 Lucerne 🢒 DTC 🢒 DTC B0071

DTC Descriptors

DTC B0071 03: Passenger Seat Belt Tension Sensor Circuit

DTC B0071 07: Passenger Seat Belt Tension Sensor Circuit

Diagnostic Fault Information

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Circuit/System Description

The inflatable restraint seat belt tension sensor is a 3-wire potentiometer mounted on the retractor or buckle side of the seat belt and provides an input to the passenger presence system (PPS). When an infant car seat is properly restrained on the front passenger seat, the seat belt is tightly secured through the car seat. The seat belt pulls on the tension sensor and changes the voltage signal to the PPS module. The PPS monitors the seat belt tension sensor circuit and if a fault is detected, DTC will be set. When the PPS detects this DTC within the PPS, it will notify the customer of the enable/disable status by turning ON the OFF indicator on the PASSENGER AIR BAG ON/OFF indicators. Then the PPS will communicate to the sensing and diagnostic module (SDM) through a serial data communications that a PPS fault is present. The SDM will then suppress the deployment of the instrument panel (I/P) module and then turn the AIR BAG indicator ON.

Conditions for Running the DTC

Ignition voltage is between 9-16 volts.

Conditions for Setting the DTC
    • The PPS detects the voltage at the passenger seat belt tension retractor sensor signal is less than 0.05 volt or greater than 4.5 volts for 500 milliseconds.
    • The PPS detects the voltage at the passenger seat belt tension retractor sensor 5-volt reference is less than 4.5 volts or greater than 9.1 volts for 500 milliseconds.
    • The PPS detects the amperage at the passenger seat belt tension retractor sensor low reference is 25 MA or greater for 500 milliseconds.

Action Taken When the DTC Sets
    • The PPS will set a DTC, and then communicate with the SDM via serial data communications.
    • The SDM disables the I/P module deployment loop.
    • The PPS will turn ON the passenger air bag status OFF indicator.
    • The SDM commands the AIR BAG indicator ON via GMLAN serial data.

Conditions for Clearing the DTC
    • The condition responsible for setting the DTC no longer exists and the scan tool Clear DTCs function is used.
    • A history DTC will clear once 255 malfunction-free ignition cycles have occurred.

Diagnostic Aids

Inspect the passenger seat belt tension retractor sensor signal, 5-volt reference, and low reference circuits carefully for cutting and/or chafing.

Reference Information

Electrical Information Reference

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

Circuit/System Testing

Important: 

   • The seat belt tension retractor sensor is not serviced separately. The seat belt retractor pretensioner replacement - right front with the seat belt tension retractor sensor must be serviced as a complete unit.
   • When removing connectors, inspect for damage or corrosion. Damage or corrosion in the following requires repair or replacement of the affected component/connector:
      - The seat belt retractor pretensioner - RF
      - The PPS module
      - The seat belt retractor pretensioner - RF wiring harness connector
      - The PPS wiring harness connector

  1. Ignition OFF, disconnect the seat belt tension retractor sensor. Refer to SIR Identification Views for location of connector.
  2. Disconnect the PPS module connector.
  3. Test the seat belt tension retractor sensor signal circuit for a short to ground, a high resistance, or an open. Verify that a short to ground, a high resistance, or an open does not exist.
    4. ⇒If any of the above conditions are found, make the appropriate repair.
  4. Test the seat belt tension retractor sensor 5-volt reference circuit for a short to ground, a short to voltage, a high resistance, or an open. Verify that a short to ground, a short to voltage, a high resistance, or an open does not exist.
    5. ⇒If any of the above conditions are found, make the appropriate repair.
  5. Test the seat belt tension retractor sensor low reference circuit for a short to ground, a short to voltage, a high resistance, or an open. Verify that a short to ground, a short to voltage, a high resistance, or an open does not exist.
    6. ⇒If any of the above conditions are found, make the appropriate repair
  6. Ignition ON, engine OFF test the seat belt tension retractor sensor circuit with a DMM. Measure the voltage of the seat belt tension retractor sensor circuit harness side and ground. The voltage should read 0.05-4.5 volts.
    7. ⇒If the voltage is more than 5 volts, test the seat belt tension retractor sensor circuit for a short to voltage. If the circuit tests good, replace the PPS.
  7. Reconnect all PPS components. Use the scan tool to clear all PPS DTCs. Rezero the PPS. Refer to Passenger Presence System Rezeroing . Verify DTC B0071 does not exist.
    8. ⇒If DTC B0071 reset, replace the PPS.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Seat Belt Retractor Pretensioner Replacement - Front
    •  Control Module References for PPS replacement, setup, and programming