For 1990-2009 cars

### 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 B0073 01: RF Seat Belt Sensor Circuit Short to Battery
DTC B0073 02: RF Seat Belt Sensor Circuit Short to Ground
DTC B0073 04: RF Seat Belt Sensor Circuit Open Circuit
DTC B0073 06: Right Front Seat Belt Sensor Circuit Short To Ground or Open Circuit

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Low Reference | -- | B0073 04, 06 | -- | --
Right Front Seat Belt Switch Signal | B0073 02, 06 | B0073 04, 06 | B0073 01 | --

### Circuit/System Description

The inflatable restraint seat belt buckle sensor 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 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.

### Action Taken When the DTC Sets

• | The SDM sets a DTC B0073.

• | The SDM commands ON the AIR BAG warning lamp via serial data communications.

### Conditions for Clearing the DTC

• | The condition responsible for setting the DTC no longer exists and the scan tool Clear DTCs function is used.

• | A history DTC will clear once 255 malfunction-free ignition cycles have occurred.

### Reference Information

#### Schematic Reference

Seat Belt Schematics

#### Connector End View Reference

Seat Belt Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

### Circuit/System Testing

Important:

• | The seat belt buckle sensor is not serviced separately. The seat belt buckle with the seat belt buckle sensor 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 buckle sensor wiring harness connector

- | The seat belt buckle sensor

- | The SDM wiring harness connector

1. Ignition OFF, disconnect the seat belt sensor connector.
2. Test for less than 1.0 ohm of resistance between low reference terminal B 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 A 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 buckle.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Front Seat Belt Buckle Replacement

• | SIR/SRS Wiring Repairs

• | Control Module References for SDM and PPS replacement, setup, and programming