DTC B0079 or B0080

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 04: Driver Seat Position Sensor Circuit Open
• DTC B0079 05: Driver Seat Position Sensor Circuit High Voltage or Open
• DTC B0079 06: Driver Seat Position Sensor Circuit Low Voltage or Open
• DTC B0079 08: Driver Seat Position Sensor Circuit Signal Invalid
• DTC B0079 0C: Driver Seat Position Sensor Circuit Low Current
• DTC B0080 01: Passenger Seat Position Sensor Circuit Short to Battery
• DTC B0080 02: Passenger Seat Position Sensor Circuit Short to Ground
• DTC B0080 04: Passenger Seat Position Sensor Circuit Open
• DTC B0080 05: Passenger Seat Position Sensor Circuit High Voltage or Open
• DTC B0080 06: Passenger Seat Position Sensor Circuit Low Voltage or Open
• DTC B0080 08: Passenger Seat Position Sensor Circuit Signal Invalid
• DTC B0080 0C: Passenger Seat Position Sensor Circuit Low Current

Diagnostic Fault Information

Circuit/System Description

The seat position sensor determines the proximity of the front driver or passenger seat to the frontal air bag. It has two states: forward and rearward. The sensor interfaces with the Inflatable Restraint Sensing and Diagnostic Module (SDM). The SDM uses this input to disable stage 2 of the frontal air bag for a front seat positioned forward of a specific point in the seat track. The sensor provides two current ranges: one for the forward seat position and one for the rearward position.

When the SDM receives input indicating the seat is rearward, it will not disable stage 2 deployment. When the seat is forward, the SDM will disable stage 2 deployment. If the SDM detects a fault in the seat position sensor circuit, it will set DTC B0079 or B0080 and disable stage 2 frontal deployment.

Conditions for Running the DTC

Ignition voltage is between 9-16 V.

Conditions for Setting the DTC

• B0079 01, B0080 01: The SDM detects the seat position sensor signal circuit is shorted to voltage for 2 seconds.
• B0079 02, B0080 02: The SDM detects the seat position sensor signal circuit is shorted to ground for 2 seconds.
• B0079 04, B0080 04: The SDM detects the seat position sensor signal circuit is open for 2 seconds.
• B0079 05, B0080 05: The SDM detects the seat position sensor signal circuit is open or has a high voltage condition for 2 seconds.
• B0079 06, B0080 06: The SDM detects the seat position sensor signal circuit is shorted to ground or an open for 2 seconds.
• B0079 08, B0080 08: The SDM detects an invalid signal on the seat position sensor signal circuit.
• B0079 0C, B0080 0C: The SDM detects a low current condition in the seat position sensor signal circuit for 2 seconds.

Action Taken When the DTC Sets

• The SDM defaults the seat position sensor to seat forward threshold.
• The SDM requests the instrument cluster 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 once 100 fault-free ignition cycles have occurred.

Reference Information

• Schematic Reference: SIR Schematics
• Connector End View Reference: Component Connector End Views
• Description and Operation: Supplemental Inflatable Restraint System Description and Operation
• Electrical Information Reference:
  • Circuit Testing
  • Testing for Intermittent Conditions and Poor Connections
  • Wiring Repairs
  • Connector Repairs
• Scan Tool Reference: Control Module References for scan tool information

Circuit/System Verification

1. Verify that DTC B0079 08 or B0080 08 is not set.
   • If the DTC is set with the symptom byte 08: Replace the appropriate seat position sensor.
   • If the DTC is not set with the symptom byte 08: Proceed to step 2.
2. Verify that DTC B0079 or B0080 is not set.
   • If the DTC is set: Refer to Circuit/System Testing.
   • If the DTC is not set: Proceed to step 3.
3. Ignition ON, observe the appropriate scan tool seat position sensor parameter. Verify the parameter is either forward or rearward.
   • If the parameter is neither forward or rearward: Refer to Circuit/System Testing.
   • If the parameter is either forward or rearward: Proceed to step 4.
4. With the seat un-occupied, observe the scan tool while moving the seat to the full forward and then full rearward positions. Verify the seat position sensor parameter varies between Forward and Rearward.
   • If the parameter does not vary: Refer to Circuit/System Testing.
   • If the parameter varies between Forward and Rearward: All OK.

Circuit/System Testing

Note: 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
• Inflatable Restraint Sensing and Diagnostic Module
• Seat position sensor wiring harness connector
• Inflatable Restraint Sensing and Diagnostic Module wiring harness connector

1. Ignition OFF, disconnect the harness connector at the appropriate seat position sensor.
2. Test for less than 10 Ω between the low reference circuit terminal 1 and ground.
   • If 10 Ω or greater:
     1. Disconnect the X2 harness connector at the Inflatable Restraint Sensing and Diagnostic Module.
     2. Test for less than 2 Ω in the low reference circuit end to end.
        • If 2 Ω or greater, repair the open/high resistance in the circuit.
        • If less than 2 Ω, replace the Inflatable Restraint Sensing and Diagnostic Module.
   • If less than 10 Ω: Proceed to step 3.
3. Ignition ON, test for 4–9 V between the signal circuit terminal 2 and ground.
   • If less than 4 V:
     1. Ignition OFF. Disconnect the X2 harness connector at the Inflatable Restraint Sensing and Diagnostic Module.
     2. Test for infinite resistance between the control circuit and ground.
        • If less than infinite resistance, repair the short to ground on the circuit.
     3. Test for less than 2 Ω in each control circuit end to end.
        • If 2 Ω or greater, repair the open/high resistance in the circuit.
        • If less than 2 Ω, replace the Inflatable Restraint Sensing and Diagnostic Module.
   • If greater than 9 V:
     1. Ignition OFF, disconnect the X2 harness connector at the Inflatable Restraint Sensing and Diagnostic Module. Ignition ON.
     2. Test for less than 1 V between the control circuit and ground.
        • If 1 V or greater, repair the short to voltage on the circuit.
4. If within the specified range: Replace the Seat Position Sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• Inflatable Restraint Seat Position Sensor Replacement
• SIR/SRS Wiring Repairs
• Control Module References for Inflatable Restraint Sensing and Diagnostic Module replacement, programming, and setup