Diagnostic Instructions

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 05: Passenger Seat Belt Sensor Circuit Short to Battery or Open

DTC B0073 08: Passenger Seat Belt Sensor Circuit Signal Invalid

Diagnostic Fault Information

Circuit	Short to Ground	High Resistance	Open	Short to Voltage	Signal Performance
Driver Seat Belt Sensor Signal	B0072 02, 1	B0072 05, 2	B0072 05, 2	B0072 01, 2	B0072 08
Driver Seat Belt Sensor Low Reference	--	B0072 05, 2	B0072 05, 2	2	B0072 08
Passenger Seat Belt Sensor Signal	B0073 02, 1	B0073 05 , 2	B0073 05, 2	B0073 01, 2	B0073 08
Passenger Seat Belt Sensor Low Reference	--	B0073 05, 2	B0073 05, 2	2	B0073 08
1. Indicator will remain ON with seat belt buckled. 2. Indicator will illuminate only for the bulb test.

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

B0073 01

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

B0073 02

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

B0073 05

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

B0073 08

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

Action Taken When the DTC Sets

Conditions for Clearing the DTC

Reference Information

Schematic Reference

Connector End View Reference

Component Connector End Views

Description and Operation

SIR System Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Ignition ON, observe the scan tool Passenger 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 wiring harness connector

•	Seat belt sensor

•	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 Passenger Seat Belt Switch parameter is Buckled.

⇒	If not the specified value, test the signal circuit for 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 Passenger 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 after completing the diagnostic procedure.