Hummer H3. Manual — part 620

panel.

Inflatable Restraint Seat Position Sensors (SPS)

The 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 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 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 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. Its important to understand that the SPS is
secondary to the passenger presence system (PPS) in the disable mode the passenger air bag will
not deploy regardless of the SPS status.

Inflatable Restraint Passenger Seat Belt Tension Sensor

The seat belt tension sensor is used to enhance the Passenger Presence System (PPS) when an
infant car seat is properly restrained on the front outboard passenger seat. The seat belt tension
sensor is a 3-wire potentiometer mounted on the lower seat belt anchor and provides an input to
the PPS module. When an infant car seat is properly restrained on the front passenger seat, the
seat belt is tightly secured through the infant car seat. The seat belt pulls on the tension sensor and
changes the voltage signal to the PPS module. The PPS module uses the voltage signal to help
determine if a tightly belted infant car seat is installed. The PPS uses the inputs from the seat belt
tension sensor and the PPS pressure sensor to determine if the instrument panel (I/P) module
should be suppressed or enabled. The PPS monitors the seat belt tension sensor circuits and sets
DTC 023 if a fault is detected. To determine what DTCs have been set by the PPS, the Tech 2 is
used to command the SDM to request the PPS to flash the DTCs using the PASSENGER AIR
BAG ON/OFF indicators located on the instrument panel.

Inflatable Restraint Vehicle Rollover Sensor

The vehicle rollover sensor is used to supplement the side Supplemental Inflatable Restraint

2007 Hummer H3

2007 RESTRAINTS Supplemental Inflatable Restraints - H3

(SIR) System. The sensing and diagnostic module (SDM) uses the input from the vehicle rollover
sensor to assist in determining the severity of a vehicle rollover or near rollover condition. If the
SDM determines a deployment is warranted, the SDM will cause current to flow through the
deployment loops deploying the inflatable restraint roof rail modules.

AIR BAG Indicator

The AIR BAG indicator, located on the instrument panel cluster (IPC) is used to notify the driver
of Supplemental Inflatable Restraint (SIR) System malfunctions and to verify that the sensing and
diagnostic module (SDM) is communicating with the IPC. When the ignition is turned ON, the
SDM is supplied with ignition 1 voltage and requests the IPC to flash the AIR BAG indicator 7
times. While flashing the indicator, the SDM conducts test on all SIR system components and
circuits. If no malfunctions are detected the SDM will communicate with the IPC through the
class 2 serial data circuit and request the IPC to turn the AIR BAG indicator OFF. The SDM
provides continuous monitoring of the air bag circuits by conducting a sequence of checks. If a
malfunction is detected the SDM will store a diagnostic trouble code (DTC) and request the IPC
to turn the AIR BAG indicator ON. The presence of a SIR system malfunction could result in
non-deployment of the air bags. The AIR BAG indicator will remain ON until the malfunction
has been repaired.

Inflatable Restraint PASSENGER AIR BAG ON/OFF Indicators

The PASSENGER AIR BAG ON/OFF indicators located on the instrument panel are used to
notify the driver when the Passenger Presence System (PPS) has enabled or disabled the
instrument panel (I/P) inflator module. The PPS air bag indicators will also inform the driver of
any PPS malfunctions. When the ignition is turned on, the PPS module is supplied with ignition 1
voltage and commands both PASSENGER AIR BAG ON/OFF indicators ON for 5 seconds. The
PPS module conducts tests on the PPS components and circuits while both ON/OFF indicators
are ON. If no malfunctions are detected the PPS module will turn the PASSENGER AIR BAG
indicator ON or OFF depending on the status of the PPS. If a malfunction is detected, the PPS
module will store a diagnostic trouble code (DTC), default the PPS to the OFF state and
communicate with the sensing and diagnostic module (SDM) that a DTC has been set. When the
SDM detects that the PPS has set a DTC, the SDM will set either DTC B0092 or B0098 and
request the instrument panel cluster (IPC) to turn the AIR BAG indicator located on the IPC ON.
This is done to notify the driver of any PPS malfunctions. The presence of a Supplemental
Inflatable Restraint (SIR) System malfunction could result in non-deployment of the air bags. The
AIR BAG indicator will remain ON until the malfunction has been repaired.

Dual Stage Inflator Modules

Dual stage inflator modules contain a housing, inflatable air bag, 2 initiating devices, canister of

2007 Hummer H3

2007 RESTRAINTS Supplemental Inflatable Restraints - H3

gas generating material and, in some cases, stored compressed gas. The 2 initiators are part of the
inflator module deployment loop. The inflator modules have 2 stages of deployment, which varies
the amount of restraint to the occupant according to the collision severity. For moderate frontal
collisions the inflator modules deploy at less than full deployment which consists of stage 1 of the
inflator module. For more severe frontal collisions a full deployment is initiated which consists of
stage 1 and stage 2 of the inflator module. When the vehicle is involved in a collision of sufficient
force, the sensing and diagnostic module (SDM) will cause current to flow through the
deployment loops to the initiator. Current passing through the initiator ignites the material in the
canister producing a rapid generation of gas and the release of compressed gas, if present. The gas
produced from this reaction rapidly inflates the air bag. Once the air bag is inflated it quickly
deflates through the air bag vent holes.

Each dual stage inflator module is equipped with a shorting bar located on the connectors of the
module. The shorting bar shorts the inflator module deployment loop circuitry to prevent
unwanted deployment of the air bag when it is disconnected.

Inflatable Restraint Steering Wheel Module Coil

The steering wheel module coil is attached to the steering column and is located under the
steering wheel. The steering wheel module coil consists of 2 or more current-carrying coils. The
coils allow the rotation of the steering wheel while maintaining continuous electrical contact
between the driver deployment loop and the steering wheel module. Four coil wires are used for
the steering wheel module deployment loop. Additional coil wires are used for accessories
attached to the steering wheel depending on the vehicle model. The steering wheel module coil
connector is located near the base of the steering column. The connector contains a shorting bar
that shorts the steering wheel module coil deployment loop circuitry to prevent unwanted
deployment of the air bag when it is disconnected.

Inflatable Restraint Front End Sensors

The front end sensors are equipped on vehicles to supplement the Supplemental Inflatable
Restraint (SIR) System performance. The front end sensors are electronic and are not part of the
deployment loops, but instead provide inputs to the sensing and diagnostic module (SDM). The
front end sensors can assist in determining the severity of some frontal collisions. The SDM uses
the input from the front end sensors to assist in determining the severity of a frontal collision
further supporting air bag deployment. If the SDM determines a deployment is warranted, the
SDM will cause current to flow through the deployment loops deploying the frontal air bags.

Inflatable Restraint Wiring Harnesses

The wiring harnesses connect the sensing and diagnostic module (SDM), inflator modules,
Passenger Presence System (PPS), front end sensors, seat position sensors (SPS), passenger seat

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2007 RESTRAINTS Supplemental Inflatable Restraints - H3

belt tension retractor sensor and the class 2 serial data circuit together using weather pack
connectors. SIR deployment loop connectors are yellow in color for easy identification. When
repairing Supplemental Inflatable Restraint (SIR) System wiring harnesses, follow the proper
testing and wiring repair procedures outlined in this manual.

Seat Belt Pretensioner

The seat belt pretensioner consist of a housing, a seat belt retractor, the seat belt webbing, an
initiator and a canister of gas generating materials. The initiator is part of the seat belt
pretensioner deployment loop. When the vehicle is involved in a collision of sufficient force, the
sensing and diagnostic module (SDM) causes current to flow through the seat belt deployment
loops to the initiator. Current passing through the initiator ignites the material in the canister
producing a rapid generation of gas. The gas produced from this reaction deploys the seat belt
pretensioner and retracts the seat belt webbing, which removes all of the slack in the seat belts.
Depending on the severity of the collision, the seat belt pretensioner may deploy without the
frontal inflator modules deploying or they will deploy immediately before the frontal inflator
modules deploy. The seat belt pretensioner will deploy immediately before the frontal inflator
modules deploy. Each seat belt pretensioner is equipped with a shorting bar that is located in the
connector of the seat belt pretensioner. The shorting bar shorts the seat belt pretensioner circuitry
to prevent unwanted deployment of the seat belt pretensioner when the connector is disconnected.

Steering Wheel and Column

The steering wheel and column are designed to absorb energy when driver contact is made with
the steering wheel or inflated air bag. In a frontal collision the driver may contact the steering
wheel directly or load the steering wheel and column through the inflated air bag. When the
driver applies load to the air bag or steering wheel the column will compress downward
absorbing some of the impact, helping to reduce bodily injuries to the driver. The steering wheel
and column must be inspected for damage after a collision.

Driver and Passenger Knee Bolsters

The knee bolsters are designed to help restrain the lower torsos of front seat occupants by
absorbing energy through the front seat occupants upper legs. In a frontal collision the front seat
occupants legs may come in contact with the knee bolsters. The knee bolsters are designed to
crush or deform absorbing some of the impact, which helps to reduce bodily injuries. The driver
and passenger knee bolsters are located in the lower part of the instrument panel and must be
inspected for damage after a collision.

SPECIAL TOOLS AND EQUIPMENT

SPECIAL TOOLS

2007 Hummer H3

2007 RESTRAINTS Supplemental Inflatable Restraints - H3