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 BatteryDTC 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
Connector End View Reference
Description and Operation
SIR System Description and Operation
Electrical Information Reference
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
- Ignition OFF, disconnect the harness connector at the SPS.
- Disconnect the harness connector at the SDM.
- Ignition ON, test for less than 1 volt between the SPS signal circuit terminal 29 and ground.
- Ignition ON, test for less than 1 volt between the SPS low reference circuit terminal 28 and ground.
- Test for infinite resistance between the SPS signal circuit terminal 29 and ground.
- Test for less than 1 ohm between the SPS signal circuit terminal 2 and the SDM terminal 29.
- Test for less than 1 ohm between the SPS low reference circuit terminal 1 and the SDM terminal 28.
- If all circuits test normal, replace the SPS.
- Reconnect all SIR components. Ignition ON, with a scan tool clear and recheck for DTCs.
| ⇒ | If greater than the specified range, test the circuit for a short to voltage. |
| ⇒ | If greater than the specified range, test the circuit for a short to voltage. |
| ⇒ | If less than the specified value, test the circuit for a short to ground. |
| ⇒ | If greater than the specified range, test the circuit for an open/high resistance. |
| ⇒ | If greater than the specified range, test the circuit for an open/high resistance. |
| ⇒ | If the front end sensor DTC returns and is current, replace the SDM. After replacement, refer to Repair Verification. |
Repair Instructions
| • | 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. |
