GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2008 🢒 Escalade ESV 🢒 DTC 🢒 DTC B0079

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using the 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: LF Seat Position Sensor Circuit Short to Battery

DTC B0079 02: LF Seat Position Sensor Circuit Short to Ground

DTC B0079 04: LF Seat Position Sensor Circuit Open

DTC B0079 06: LF Seat Position Sensor Circuit Short to Ground or Open Circuit

DTC B0079 08: LF Seat Position Sensor Circuit Signal Invalid

Diagnostic Fault Information

Circuit

Short to Ground

High Resistance

Open

Short to Voltage

Signal Performance

Seat Position Sensor Left Low Reference

B0079 02, 06

B0079 04

B0079 04

B0079 01

B0079 08

Seat Position Sensor Left Signal

B0079 02, 06

B0079 04

B0079 04

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 inboard 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 circuit is shorted to voltage for 500 milliseconds.

B0079 06

The SDM detects the SPS circuit is shorted to ground or an open occur for 500 milliseconds.

B0079 08

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

Action Taken When the DTC Sets
    • The SDM sets a DTC B0079.
    •  The SDM defaults the SPS to seat rearward 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 no longer exists.
    • A history DTC will clear once 100 malfunction-free ignition cycles have occurred.

Reference Information

Schematic Reference

SIR Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

SIR System Description and Operation

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 (SPS)
   • Sensing and diagnostic module (SDM) module
   • Seat position sensor wiring harness connector
   • SDM wiring harness connector

  1. Ignition OFF, disconnect the harness connector at the SPS.
  2. Disconnect the harness connector at the SDM.
  3. Ignition ON, test for less than 1 volt between the SPS signal circuit terminal 29 and ground.
    4. ⇒If greater than the specified range, test the circuit for a short to voltage.
  4. Ignition ON, test for less than 1 volt between the SPS low reference circuit terminal 28 and ground.
    5. ⇒If greater than the specified range, test the circuit for a short to voltage.
  5. Test for infinite resistance between the SPS signal circuit terminal 29 and ground.
    6. ⇒If less than the specified value, test the circuit for a short to ground.
  6. Test for less than 1 ohm between the SPS signal circuit terminal 2 and the SDM terminal 29.
    7. ⇒If greater than the specified range, test the circuit for an open/high resistance.
  7. Test for less than 1 ohm between the SPS low reference circuit terminal 1 and the SDM terminal 28.
    8. ⇒If greater than the specified range, test the circuit for an open/high resistance.
  8. If all circuits test normal, replace the SPS.
  9. Reconnect all SIR components. Ignition ON, with a scan tool clear and recheck for DTCs.
    10. ⇒If the front end sensor DTC returns and is current, replace the SDM. After replacement, refer to Repair Verification.

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

Repair Verification

Ignition ON, use the scan tool to clear the DTCs then recheck for DTCs. Verify no DTCs are set.

⇒If DTC B0079 was current, replace the SDM.