B0073

DTC B0073

Diagnostic Instructions

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

DTC Descriptors
DTC B0073 01
- Passenger Seat Belt Sensor Circuit Short to Battery

DTC B0073 02
- Passenger Seat Belt Sensor Circuit Short to Ground

DTC B0073 04
- Passenger Seat Belt Sensor Circuit Open Circuit

DTC B0073 06
- Passenger Seat Belt Sensor Circuit Short To Ground or Open Circuit

DTC B0073 08
- Passenger 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 V.

Conditions for Setting the DTC

B0073 01

The SDM detects the seat switch signal circuit or low reference circuit is shorted to voltage for 500 milliseconds.

B0073 02

The SDM detects the seat switch signal circuit or low reference circuit is shorted to ground for 500 milliseconds.

B0073 04

The SDM detects the seat switch signal circuit or low reference circuit is open for 500 milliseconds.

B0073 06

The SDM detects the seat switch signal circuit or low reference circuit is shorted to ground or an open for 500 milliseconds.

B0073 08

The SDM detects an invalid signal in the seat switch signal circuit.

Action Taken When the DTC Sets

The SDM commands the AIR BAG indicator ON.

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

* 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 (SIR System Description and Operation)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
* Connector Repairs (Connector Repairs)

Scan Tool Reference

Programming and Relearning (Programming and Relearning) for scan tool information.

Circuit/System Verification

1. Ignition ON, command the instrument panel cluster (IPC) Lamp Test with a scan tool. The passenger seat belt indicator should turn ON and OFF when changing between the commanded states.

• If the indicator is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the IPC.
• If the indicator is always OFF, test the control circuit for a short to voltage. If the circuit tests normal, replace the IPC.

2. Monitor the SDM Passenger Seat Belt Switch parameter while connecting and disconnecting the seat belt. The parameter should display Buckled and Unbuckled when changing seat belt states.

Circuit/System Testing

Note:
* Refer to SIR Service Precautions (Technician Safety Information).
* The seat belt buckle switch is not serviced separately. The seat belt buckle with the seat belt buckle switch 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 SDM
- The seat belt buckle switch wiring harness connector
- The seat belt buckle switch
- The SDM wiring harness connector

1. Ignition OFF, disconnect the harness connector at the seat belt switch.
2. Test for less than 1.0 ohm between low reference terminal 2 and ground.

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

3. Ignition ON, with the passenger seat belt unbuckled, verify the scan tool Passenger Seat Belt Switch parameter displays Unbuckled.

• If not the specified value, test the signal circuit terminal 1 for short to ground. If the circuit tests normal, replace the SDM.

4. Install a 3 A fused jumper wire between the signal circuit terminal 1 and the low reference circuit terminal 2. Verify the scan tool Passenger Seat Belt Switch parameter displays Buckled.

• 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 switch.

Component Testing

1. Ignition OFF, disconnect the harness connector at the seat belt switch.
2. With the seat belt buckled, test for infinite resistance between the signal circuit terminal 1 and the low reference terminal 2.

• If not the specified range, replace the seat belt switch.

3. With the seat belt unbuckled, test for less than 2 ohm between the signal circuit terminal 1 and the low reference terminal 2.

• If greater than the specified range, replace the seat belt 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 (SIR/SRS Wiring Repairs)
* Control Module References (Programming and Relearning) for SDM replacement, setup, and programming