GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2009 🢒 Express 🢒 DTC 🢒 DTC B0074

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 B0074 03: Passenger Occupant Classification Sensor Circuit Voltage Below Threshold

DTC B0074 07: Passenger Occupant Classification Sensor Circuit Voltage Above Threshold

DTC B0074 08: Passenger Occupant Classification Sensor Circuit Signal Invalid

Circuit/System Description

The passenger presence system (PPS) uses a sensor mat located underneath the passenger seat cushion to measure the weight of the occupant sitting in the front passenger seat. The PPS continually monitors itself and if a fault occurs, a DTC will set. When the PPS detects a fault, it will illuminate the OFF indicator on the PASSENGER AIR BAG ON/OFF indicators. Then the PPS will communicate to the SDM through 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 illuminate the AIR BAG indicator.

Conditions for Running the DTC

Ignition voltage is between 9-16 volts.

Conditions for Setting the DTC

The PPS detects a failure within itself.

Action Taken When the DTC Sets
    • The PPS will set a DTC, and then communicate with the SDM.
    • The SDM disables the I/P module deployment loop.
    • The PPS will illuminate the passenger air bag status OFF indicator.
    • The SDM requests the instrument panel cluster (IPC) to illuminate the AIR BAG indicator.

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

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

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

       • PPS module
       • PPS module wiring harness connector

  1. Ignition OFF, disconnect the harness connector at the PPS module.
  2. Ignition OFF, test for less than 1 ohm between the ground circuit terminal D and ground.
    3. ⇒If greater then the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify a test lamp illuminates between the B+ circuit terminal A and ground.
    4. ⇒If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
  4. Reconnect all PPS components and perform the Passenger Presence System Rezeroing. Verify DTC B0074 is not set as current.
    5. ⇒If DTC B0074 is set, replace the PPS.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  SIR/SRS Wiring Repairs
    •  Control Module References for PPS replacement, setup, and programming