GM Service Manual Online
For 1990-2009 cars only

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 00: Passenger Occupant Classification Sensor

DTC B0074 0D: Passenger Occupant Classification Sensor Circuit Resistance Above Threshold

DTC B0074 0E: Passenger Occupant Classification Sensor Circuit Resistance Below Threshold

DTC B0074 0F: Passenger Occupant Classification Sensor Circuit Erratic (Wet Seat)

Diagnostic Fault Information

Circuit

Short to Ground

Low Resistance

High Resistance

Open

Short to Voltage

Performance

Pressure Sensor Signal

--

B0074 0E

B0074 0D

B0074 0D

--

B0074 0F

Pressure Sensor Voltage Reference

--

B0074 0E

B0074 0D

B0074 0D

--

--

Pressure Sensor Low Reference

--

B0074 0E

B0074 0D

B0074 0D

--

--

Circuit/System Description

The passenger presence system (PPS) sensor continually monitors itself and if a fault in this circuit occurs, a DTC will set. When the sensing and diagnostic module (SDM) detects this DTC within the PPS, it will notify the customer of the enable/disable status by illuminating 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 disable the deployment of the instrument panel (I/P) module and then illuminate the AIR BAG warning indicator.

Conditions for Running the DTC

Ignition voltage is between 9-16 volts.

Conditions for Setting the DTC

    • The PPS detects the voltage at the pressure sensor signal is less than 0.5 volts or greater than 4.5 volts for 500 milliseconds.
    • The PPS detects the voltage at the pressure sensor voltage reference is less than 4.5 volts or greater than 9.1 volts for 500 milliseconds.
    • The PPS detects the amperage at the PPS sensor low reference is 25 mA or greater for 500 milliseconds.

Action Taken When the DTC Sets

    • The SDM disables the I/P module deployment loop.
    • The SDM will illuminate the OFF portion of the PASSENGER AIR BAG ON/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 pressure sensor
   • PPS pressure sensor wiring harness connector

  1. Verify that DTC B0074 0F is not set.
  2. If the DTC is set, verify the seat is dry. If the seat is wet, allow 24-48 hours dry time.
  3. Ignition OFF, disconnect the harness connector at the PPS sensor.
  4. Test for less then 10 ohms between the ground circuit terminal 4 and ground.
  5. If greater then the specified range, test the ground circuit for an open/high resistance.
  6. Ignition ON, verify a test lamp illuminates between the B+ circuit terminal 3 and ground.
  7. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
  8. Ignition OFF, disconnect the harness connector at the inflatable restraint rollover sensor.
  9. Test for infinite resistance between the signal circuit terminal 1 and ground.
  10. If less than the specified value, test the signal circuit for a short to ground.
  11. Ignition ON, test for less than 1 volt between the signal circuit terminal 1 and ground.
  12. If greater than the specified range, test the signal circuit for a short to voltage.
  13. Test for less than 1 ohm on the signal circuit between the PPS sensor terminal 1 and the rollover sensor terminal 3.
  14. If greater than the specified range, test the signal circuit for open/high resistance.
  15. Reconnect all PPS components and perform the Passenger Presence System Preload Test procedure.
  16. Clear DTCs, verify DTC B0074 is not set.
  17. If the DTC sets, replace the PPS sensor.

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