B0084

DTC B0084

Circuit 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 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 both the driver and passenger seats. The seat track includes a metal bracket that shunts the SPS magnetic circuit creating two states of seat position. The shunted state represents a rearward seat position. The non-shunted state represents a forward position. The SPS provides two current ranges, one range for the shunted state and a second range for a non-shunted state. These two states are inputs to the sensing and diagnostic module (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 B0083 or B0084 and defaults to disabling stage 2 frontal deployment. This will only default on the side of the vehicle the sensor has a fault. It's important to understand that the SPS is secondary to the manual I/P module disable switch. If the manual I/P module disable switch is in the disable mode the passenger air bag will not deploy regardless of the SPS status.

Conditions for Running the DTC
Ignition 1 voltage is within the normal operating voltage range.

Conditions for Setting the DTC
DTC B0083 and B0084 will set when one of the following conditions occur:

^ The SDM detects the SPS circuit amperage is 4 mA or less for 500 milliseconds.
^ The SDM detects the SPS circuit amperage is between 8 mA and 11 mA for 500 milliseconds.
^ The SDM detects the SPS circuit amperage is 18 mA or greater for 500 milliseconds.

Action Taken When the DTC Sets
^ The SDM commands the AIR BAG indicator ON.
^ The SDM defaults the SPS to seat forward threshold.

Conditions for Clearing the DTC
^ The condition responsible for setting the DTC no longer exists.
^ You issue a scan tool CLEAR DTCs command.
^ A history DTC will clear once 255 malfunction free ignition cycles have occurred.

Diagnostic Aids
The following can cause an intermittent condition:

^ A short between the SPS signal and low reference circuits
^ High or low resistance in the SPS signal and low reference circuits
^ Inspect the SPS signal and return circuits carefully for cutting and/or chafing

Test Description
The numbers below refer to the step numbers on the diagnostic table:

2. Inspects the SPS connector and terminals.
6. Tests for a short to ground, a high resistance, or an open in the SPS signal circuit.
7. Tests for a short to ground, a high resistance, or an open in the SPS low reference circuit.
8. Tests for a short to voltage in the SPS signal and low reference circuits.