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 B0079 01: Driver Seat Position Sensor Circuit Short to Battery
DTC B0079 02: Driver Seat Position Sensor Circuit Short to Ground
DTC B0079 05: Driver Seat Position Sensor Circuit Short to Battery or Open
DTC B0079 08: Driver Seat Position Sensor Circuit Signal Invalid

Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance
--- | --- | --- | --- | --- | ---
Seat Position Sensor Driver Low Reference | B0079 02 | B0079 05 | B0079 05 | B0079 01 | B0079 08
Seat Position Sensor Driver Signal | B0079 02 | B0079 05 | B0079 05 | B0079 01 | B0079 08

### Circuit/System Description

The inflatable restraint seat position sensor (SPS) is used to determine the proximity of a front driver or passenger seat position with respect to the frontal air bag. The SPS interfaces with the sensing and diagnostic module (SDM). The state of the SPS allows the SDM to disable stage 2 of the frontal air bag for a front seat that is forward of a forward/rearward point in seat track travel. The SPS is a hall effect sensor that is mounted on the outboard seat track of the driver and passenger seats. The seat track includes a metal bracket that shunts the SPS magnetic circuit creating 2 states of seat position. The shunted state represents a rearward seat position. The non-shunted state represents a forward position. The SPS provides 2 current ranges, one range for the shunted state and a second range for a non-shunted state. These 2 states are inputs to the SDM, state 1 (shunted) being the rearward threshold and state 2 (non-shunted) being the forward threshold. When the SDM receives input from a SPS that state 1 threshold is reached (seat is rearward), the SDM will not disable stage 2 deployment, if required by the deployment sensors. When state 2 threshold is reached (seat is forward), the SDM will disable stage 2 deployment on the side the seat is forward. The SDM monitors the SPS circuit and if a fault is detected, the SDM will set codes B0079 and defaults to disabling stage 2 frontal deployment.

### Conditions for Running the DTC

Ignition voltage is between 9-16 volts.

### Conditions for Setting the DTC

#### B0079 01

The SDM detects the SPS signal circuit is shorted to voltage for 2 seconds.

#### B0079 02

The SDM detects the SPS signal circuit is shorted to ground for 2 seconds.

#### B0079 05

The SDM detects the SPS signal circuit is shorted to voltage or open for 2 seconds.

#### B0079 08

The SDM detects the SPS signal circuit is invalid for 500 milliseconds.

### Action Taken When the DTC Sets

• | The SDM defaults the SPS to seat forward threshold.

• | The SDM requests the instrument panel cluster (IPC) to illuminate the AIR BAG indicator.

### Conditions for Clearing the DTC

• | The condition for setting the DTC is no longer present.

• | A history DTC will clear after 250 fault-free ignition cycles.

• | The DTC can be cleared using a scan tool.

### Reference Information

#### Schematic Reference

SIR Schematics

#### Connector End View Reference

Component Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for scan tool information

### 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 position sensor

• | SDM module

• | Seat position sensor wiring harness connector

• | SDM wiring harness connector

1. Ignition OFF, disconnect the harness connector at the SPS.
2. Test for less than 1 ohm between the low reference circuit terminal B 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, test for 1.2-2.0 volts between the signal circuit terminal A and ground.

⇒ | If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the SDM.

⇒ | If less than the specified range, test the voltage reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the SDM.

4. If the circuits test normal, replace the SPS.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Front Seat Horizontal Adjuster Position Sensor Replacement.

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