B0072

DTC B0072

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.



DTC Descriptors
DTC B0072 01
- Driver Seat Belt Sensor Circuit Short to Battery

DTC B0072 02
- Driver Seat Belt Sensor Circuit Short to Ground

DTC B0072 05
- Driver Seat Belt Sensor Circuit Short to Battery or Open

DTC B0072 08
- Driver Seat Belt Sensor Circuit Signal Invalid




Diagnostic Fault Information






Circuit/System Description

The inflatable restraint seat belt buckle switch is within the seat belt buckle and provides an input to the inflatable restraint sensing and diagnostic module (SDM). The SDM supplies a low reference circuit and a seat belt switch signal circuit to determine a buckled or unbuckled condition. The SDM monitors the seat belt switch circuits and if a fault is detected a DTC will be set


Conditions for Running the DTC

Ignition voltage is between 9-16 volts.


Conditions for Setting the DTC

B0072 01

The SDM detects the seat belt sensor circuit is shorted to voltage for 2 seconds.

B0072 02

The SDM detects the seat belt sensor circuit is shorted to ground for 2 seconds.

B0072 05

The SDM detects the seat belt sensor circuit is shorted to battery or open for 2 seconds.

B0072 08

The SDM detects the seat belt sensor signal circuit is invalid for 2 seconds.


Action Taken When the DTC Sets

* The SDM requests the instrument panel cluster (IPC) to illuminate the AIR BAG indicator.
* The SDM will store the DTC.



Conditions for Clearing the DTC

* The condition for setting the DTC no longer exists.
* A history DTC will clear once 100 fault-free ignition cycles have occurred.



Reference Information
Schematic Reference

* Seat Belt Schematics ([1][2]Electrical Diagrams)
* SIR Schematics ([1][2]Air Bag Systems)

Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

SIR System Description and Operation (Description and Operation)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information


Circuit/System Verification

Ignition ON, observe the scan tool Driver Seat Belt Switch parameter while buckling and unbuckling the seat belt. The reading should be Unbuckled when the seat belt is unbuckled and the seat belt switch is closed. The reading should be Buckled when the seat belt is buckled and the seat belt switch is open.


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:


* Seat belt sensor.

* SDM.

* Seat belt sensor wiring harness connector.

* SDM wiring harness connector.




1. Ignition OFF, disconnect the harness connector of the seat belt switch.
2. Test for less than 1 ohm between low reference circuit terminal 1 and ground.

• If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the SDM.

3. Ignition ON, verify the scan tool Driver Seat Belt switch parameter is Buckled.

• If not the specified value, test the signal circuit for a short to ground. If the circuit tests normal, replace the SDM.

4. Connect a 3A fused jumper wire between the signal circuit terminal 2 and the low reference circuit terminal 1. Verify the scan tool Driver Seat Belt Switch parameter is Unbuckled.

• If not the specified value, test the signal circuit for short to voltage or an open/high resistance. If the circuit tests normal, replace the SDM.

5. If the circuits test normal, replace the seat belt buckle switch.



Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Driver or Passenger Seat Belt Buckle Replacement (Driver or Passenger Seat Belt Buckle Replacement)
* SIR/SRS Wiring Repairs (Component Tests and General Diagnostics)
* Control Module References (Programming and Relearning) for ECM replacement, setup, and programming