B0073

DTC B0072 or B0073

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions 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 04
- Driver Seat Belt Sensor Circuit Open Circuit

DTC B0072 06
- Driver Seat Belt Sensor Circuit Short To Ground or Open Circuit

DTC B0072 08
- Driver Seat Belt Sensor Circuit Signal Invalid

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

Circuit/System Description

The inflatable restraint seat belt switch is within the seat belt retractor 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, B0073 01

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

B0072 02, B0073 02

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

B0072 04, B0073 04

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

B0072 06, B0073 06

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

B0072 08, 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.
* The SDM will store a DTC.

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.

Circuit/System Testing

Important:
* The seat belt switch is not serviced separately. The seat belt retractor with the seat belt 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 module

- The seat belt switch wiring harness connector

- The seat belt switch

- The SDM wiring harness connector

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

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

3. Ignition ON. Test for 1.0 - 1.6 volts between the signal circuit terminal B and ground.

^ If less that the specified range, test the signal circuit for open/high resistance or a short to ground. If the circuit tests normal, replace the SDM.

^ If greater that the specified range, test the signal circuit for a short to voltage.

4. If the circuits test normal, replace the seat belt retractor.

Repair Instructions

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

* Seat Belt Retractor Pretensioner Replacement - Front
* SIR/SRS Wiring Repairs.