Buick Regal: 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 00

Passenger Presence Sensor Circuit Malfunction

DTC B0074 0D

Passenger Presence Sensor Resistance Above Threshold

DTC B0074 0E

Passenger Presence Sensor Resistance Below Threshold

DTC B0074 0F

Passenger Presence Sensor Erratic (Wet Seat)

Circuit/System Description

The passenger presence module monitors the sensor status continually. Whenever the sensor mat has an internal malfunction, the passenger presence module will set DTC B0074.

Conditions for Running the DTC

Ignition voltage is between 9 - 16 V.

Conditions for Setting the DTC

B0074 00

The passenger presence module has detected a disconnection from the sensor mat.

B0074 0D

The passenger presence module has detected a resistance above threshold.

B0074 0E

The passenger presence module has detected a resistance below threshold.

B0074 0F

The passenger presence module has detected a wet seat fault.

Action Taken When the DTC Sets

The inflatable restraint sensing and diagnostic module requests the instrument panel cluster 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.

Diagnostic Aids

• If either the inflatable restraint sensing and diagnostic module or passenger presence module were replaced verify that the correct part numbers were used for the vehicle application.
• If this DTC is set as either current or history it may have been caused by an electronic device. If an electronic device (computers, MP3 players, cell phones, diagnostic scan tool, power inverter, etc.) was placed on the passenger seat the passenger presence module may command the passenger air bag indicator to turn on and/or command the passenger seat belt indicator to turn on. Make sure there are no objects on the passenger seat and clear the DTCs. If this DTC resets then perform this diagnostic. If the DTC does not reset there is no further work needed on the passenger presence system.
• If this DTC is set as either current or history it may have been caused by an aftermarket seat heater. The aftermarket seat heater may command the passenger air bag indicator to turn on and/or command the

Reference Information

Schematic Reference

SIR Wiring Schematics

Connector End View Reference

Component Connector End View Index

Description and Operation

Supplemental Inflatable Restraint System Description and Operation

Electrical Information Reference

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

Scan Tool Reference

Refer to Control Module References for scan tool information.

Circuit/System Verification

NOTE: This system is serviced as a kit (seat foam, module and/or sensing mat).

Perform a Passenger Presence System Preload whenever a component is replaced, refer to Passenger Presence System Re-Zeroing. Inspect component connectors for damage or corrosion. Repair or replace the affected component/connector:

• Passenger presence module
• Passenger presence module harness connector
• Seat wiring harness to vehicle harness connector

The connector and connector position assurance (CPA) may seat independent of each other. Both the connector and CPA should seat with an audible and/or tactile click.

1. Verify the DTC remains current while moving the passenger seat forward and backward through it's full range of motion.

• If the DTC changes to History

If the status changes this could be indication of a seat to vehicle harness connection issue, refer to Circuit/System Testing.

• Go to next step: If the DTC remains Current

2. Verify with the scan tool, the fault does not change status while moving the harness near each connector listed below.

• K85 Passenger Presence Module
• B60 Passenger Presence Sensor
• Any seat harness inline
  • If the status changes

    If the reading is erratic while moving the harness, perform the following:

• Inspect each connector terminal for damage or corrosion and repair as necessary.
• Ensure each connector and CPA is correctly seated.
  • Go to next step: If the status does not change

3. All OK.

Circuit/System Testing

NOTE: This system is serviced as a kit (seat foam, module and/or sensing mat).

Perform a Passenger Presence System Preload whenever a component is replaced, refer to Passenger Presence System Re-Zeroing. Inspect component connectors for damage or corrosion. Repair or replace the affected component/connector:

1. Confirm that all passenger presence system connectors are fully seated.

2. Verify that DTC B0074 0F is not set.

• DTC B0074 0F is set.

NOTE: Verify there are no electronic devices on the passenger seat. If not, then verify the seat is dry by removing the trim from the seat bottom frame. If the seat is wet, allow 24-48 hours dry time with trim completely off. If the DTC is history, do not replace B60 Passenger Presence Sensor. Clear passenger presence module DTCs.

1. Verify there are no electronic devices on the passenger seat.
   • Completely empty the passenger seat of any objects
   • Go to next step: If the seat is empty
2. Verify the seat is dry by removing the trim from the seat bottom frame.
   • If the seat is wet, allow 24-48 hours dry time with trim completely off.
   • Go to next step: If the seat is dry
3. If the DTC is history, do not replace B60 Passenger Presence Sensor, and clear passenger presence module DTCs.

• Go to next step: DTC B0074 0F does not set.

3. Verify DTC B0074 00, B0074 0D or B0074 0E is not set.

• DTC B0074 00, B0074 0D or B0074 0E is set.

Replace the K85 Passenger Presence Module.

• Go to next step: DTC B0074 00, B0074 0D or B0074 0E do not set.

4. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

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