2006 MERCEDES-BENZ SPRINTER Service Manual

bonnet roof rack fuse diagram mirror adblue reset handbrake

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MERCEDES-BENZ SPRINTER 2006 Service Manual RESTRAINTS
DESCRIPTION
An occupant restraint system is standard factory-
installed safety equipment on this model. Available
occupant restraints for this model include both active
and passive types. A

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MERCEDES-BENZ SPRINTER 2006 Service Manual travelling end-release seat belt buckles secured to
the inboard seat track. The driver side front seat belt
buckle of all models includes an integral seat belt
switch that detects whether its seat bel

travelling end-release seat belt buckles secured to
the inboard seat track. The driver side front seat belt
buckle of all models includes an integral seat belt
switch that detects whether its seat belt has been
fastened.
²Rear Seat Belts- All rear seating positions are
equipped with three-point seat belt systems. Each
rear seating position belt employs an integral seat
cushion frame mounted inertia latch-type retractor, a
fixed position upper seat back frame mounted turn-
ing loop, and a fixed lower seat belt anchor secured
to the seat cushion frame. All rear seat belts have
fixed end-release seat belt buckles that are also
secured to the seat cushion frame.
PASSIVE RESTRAINTS
A Next Generation driver airbag is standard facto-
ry-installed safety equipment on this model, while a
passenger side front airbag and side curtain airbags
are optional. This airbag system is a passive, inflat-
able, Supplemental Restraint System (SRS) and vehi-
cles with this equipment can be readily identified by
the ªSRS - AIRBAGº logo molded into the driver air-
bag trim cover in the center of the steering wheel
and, if the vehicle is so equipped, also into the pas-
senger airbag door on the instrument panel above
the glove box (Fig. 2). Vehicles with the airbag sys-
tem can also be identified by the airbag indicator,
which will illuminate in the instrument cluster for
about six seconds as a bulb test each time the igni-
tion switch is turned to the On position. A pyrotech-
nic-type seat belt tensioner is integral to the front
seat belt retractor mounted on the lower B-pillar on
the driver side, and to the passenger side retractor of
vehicles equipped with the optional passenger side
airbag.
The supplemental restraint system includes the
following major components, which are described in
further detail elsewhere in this service information:²Airbag Control Module- The Airbag Control
Module (ACM) is located on a mount on the floor
panel within the driver side seat riser, beneath the
driver seat in the passenger compartment.
²Airbag (SRS) Indicator- The airbag indicator
is integral to the ElectroMechanical Instrument Clus-
ter (EMIC), which is located on the instrument panel
in front of the driver.
²Clockspring- The clockspring is located near
the top of the steering column, directly beneath the
steering wheel.
²Driver Airbag- The driver airbag is located in
the center of the steering wheel, beneath the driver
airbag trim cover.
²Driver Knee Blocker- The structure of the
lower instrument panel serves as a knee blocker for
the driver.
²Passenger Airbag- The optional passenger air-
bag is located within the instrument panel, behind
the passenger airbag door on the instrument panel
above the glove box on the passenger side of the vehi-
cle.
²Passenger Knee Blocker- The structure of
the glove box door and the lower instrument panel
serve as a knee blocker for the front seat passenger.
²Seat Belt Tensioner- A seat belt tensioner is
integral to the driver side front seat belt retractor
unit, and to the passenger side front seat belt retrac-
tor unit on vehicles equipped with an optional pas-
senger airbag.
²Side Curtain Airbags- Optional side curtain
airbags are available for this model when it is also
equipped with dual front airbags. In vehicles
equipped with this option, a side curtain airbag is
located on the inside of the roof side rail within a
garnish molding that extends from the A-pillar to the
B-pillar above each front door opening within the
passenger compartment of the vehicle.
²Side Impact Sensor- Two side impact sensors
are used on vehicles equipped with the optional side
curtain airbags, one on each side of the vehicle. One
sensor is located near the front of each front door
step well, concealed behind the step well trim.
The ACM contains a central processing unit and
programming that allows it to communicate on a
serial data bus diagnostic circuit connected to the
16-way Data Link Connector (DLC) located below the
left end of the instrument panel. This method of com-
munication is used for initialization of the ACM and
for diagnosis of the SRS circuits and components
using a diagnostic scan tool.
Hard wired circuitry connects the supplemental
restraint system components to each other through
the electrical system of the vehicle. These hard wired
circuits are integral to several wire harnesses, which
are routed throughout the vehicle and retained by
many different methods. These circuits may be con-
nected to each other, to the vehicle electrical system,
Fig. 2 SRS Logo
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MERCEDES-BENZ SPRINTER 2006 Service Manual and to the supplemental restraint system compo-
nents through the use of a combination of soldered
splices, splice block connectors, and many different
types of wire harness terminal connectors and in

and to the supplemental restraint system compo-
nents through the use of a combination of soldered
splices, splice block connectors, and many different
types of wire harness terminal connectors and insu-
lators. Refer to the appropriate wiring information.
The wiring information includes wiring diagrams,
proper wire and connector repair procedures, further
details on wire harness routing and retention, as well
as pin-out and location views for the various wire
harness connectors, splices and grounds.
OPERATION
ACTIVE RESTRAINTS
The primary passenger restraints in this or any
other vehicle are the standard equipment factory-in-
stalled seat belts. Seat belts are referred to as an
active restraint because the vehicle occupants are
required to physically fasten and properly adjust
these restraints in order to benefit from them. See
the owner's manual in the vehicle glove box for more
information on the features, use and operation of all
of the factory-installed active restraints.
PASSIVE RESTRAINTS
The passive restraints are referred to as a supple-
mental restraint system because they were designed
and are intended to enhance the protection for the
occupants of the vehicleonlywhen used in conjunc-
tion with the seat belts. They are referred to as pas-
sive restraints because the vehicle occupants are not
required to do anything to make them operate; how-
ever, the vehicle occupants must be wearing their
seat belts in order to obtain the maximum safety
benefit from the factory-installed supplemental
restraint system.
The supplemental restraint system electrical cir-
cuits are continuously monitored and controlled by a
microprocessor and software contained within the
Airbag Control Module (ACM). An airbag indicator in
the ElectroMechanical Instrument Cluster (EMIC)
illuminates for about four seconds as a bulb test each
time the ignition switch is turned to the On or Start
positions. Following the bulb test, the airbag indica-
tor is turned on or off by the ACM to indicate the
status of the supplemental restraint system. If the
airbag indicator comes on either solid or flashing at
any time other than during the bulb test, it indicates
that there is a problem in the supplemental restraint
system electrical circuits. Such a problem may cause
airbags not to deploy when required, or to deploy
when not required.
Deployment of the supplemental restraints
depends upon the angle and severity of an impact.
Deployment is not based upon vehicle speed; rather,
deployment is based upon the rate of deceleration as
measured by the forces of gravity (G force) upon the
impact sensor(s). When an impact is severe enough,the microprocessor in the ACM signals the inflator of
the appropriate airbag units to deploy their airbag
cushions. The front seat belt tensioners are provided
with a deployment signal by the ACM in conjunction
with the driver and passenger airbags.
During a frontal vehicle impact, the knee blockers
work in concert with properly fastened and adjusted
seat belts to restrain both the driver and the front
seat passenger in the proper position for an airbag
deployment. The knee blockers also absorb and dis-
tribute the crash energy from the driver and the
front seat passenger to the structure of the instru-
ment panel. The seat belt tensioners remove the
slack from the front seat belts to provide further
assurance that the driver and front seat passenger
are properly positioned and restrained for an airbag
deployment.
Typically, the vehicle occupants recall more about
the events preceding and following a collision than
they do of an airbag deployment itself. This is
because the airbag deployment and deflation occur so
rapidly. In a typical 48 kilometer-per-hour (30 mile-
per-hour) barrier impact, from the moment of impact
until the airbags are fully inflated takes only a few
milliseconds. Within one to two seconds from the
moment of impact, the airbags are almost entirely
deflated. The times cited for these events are approx-
imations, which apply only to a barrier impact at the
given speed. Actual times will vary somewhat,
depending upon the vehicle speed, impact angle,
severity of the impact, and the type of collision.
When the ACM monitors a problem in any of the
airbag system circuits or components, including the
seat belt tensioners, it stores a fault code or Diagnos-
tic Trouble Code (DTC) in its memory circuit and
sends a hard wired output to the EMIC to turn on
the airbag indicator. If the EMIC detects a problem
in the airbag indicator or airbag indicator circuit, the
cluster will flash the seatbelt indicator on and off.
Proper testing of the supplemental restraint system
components as well as the retrieval or erasure of a
DTC from the ACM requires the use of a diagnostic
scan tool. Refer to the appropriate diagnostic infor-
mation.
See the owner's manual in the vehicle glove box for
more information on the features, use and operation
of all of the factory-installed passive restraints.
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MERCEDES-BENZ SPRINTER 2006 Service Manual WARNINGS - RESTRAINT SYSTEM
WARNING: To avoid personal injury or death, during
and following any seat belt service, carefully
inspect all seat belts, buckles, mounting hardware,
retractors, tether str

WARNINGS - RESTRAINT SYSTEM
WARNING: To avoid personal injury or death, during
and following any seat belt service, carefully
inspect all seat belts, buckles, mounting hardware,
retractors, tether straps, and anchors for proper
installation, operation, or damage. Replace any belt
that is cut, frayed, or torn. Straighten any belt that
is twisted. Tighten any loose fasteners. Replace any
belt that has a damaged or inoperative buckle or
retractor. Replace any belt that has a bent or dam-
aged latch plate or anchor plate. Never attempt to
repair a seat belt component. Always replace dam-
aged or faulty seat belt components with the cor-
rect, new and unused replacement parts listed in
the DaimlerChrysler Mopar Parts Catalog.
WARNING: To avoid personal injury or death, on
vehicles equipped with airbags, disable the supple-
mental restraint system before attempting any
steering wheel, steering column, airbag, seat belt
tensioner, impact sensor, or instrument panel com-
ponent diagnosis or service. Disconnect and isolate
the battery negative (ground) cable, then wait two
minutes for the system capacitor to discharge
before performing further diagnosis or service. This
is the only sure way to disable the supplemental
restraint system. Failure to take the proper precau-
tions could result in accidental airbag deployment.
WARNING: To avoid personal injury or death on
vehicles equipped with airbags, before performing
any welding operations disconnect and isolate the
battery negative (ground) cable and disconnect all
wire harness connectors from the Airbag Control
Module (ACM). Failure to take the proper precau-
tions could result in accidental airbag deployment
and other possible damage to the supplemental
restraint system circuits and components.
WARNING: To avoid personal injury or death, do not
attempt to dismantle an airbag unit or tamper with
its inflator. Do not puncture, incinerate, or bring
into contact with electricity. Do not store at temper-
atures exceeding 93É C (200É F). An airbag inflator
unit may contain sodium azide and potassium
nitrate. These materials are poisonous and
extremely flammable. Contact with acid, water, or
heavy metals may produce harmful and irritating
gases (sodium hydroxide is formed in the presence
of moisture) or combustible compounds. An airbag
inflator unit may also contain a gas canister pres-
surized to over 2500 psi.WARNING: To avoid personal injury or death, when
handling a seat belt tensioner retractor, proper care
should be exercised to keep fingers out from under
the retractor cover and away from the seat belt
webbing where it exits from the retractor cover.
WARNING: To avoid personal injury or death,
replace all restraint system components only with
parts specified in the DaimlerChrysler Mopar Parts
Catalog. Substitute parts may appear interchange-
able, but internal differences may result in inferior
occupant protection.
WARNING: To avoid personal injury or death, the
fasteners, screws, and bolts originally used for the
restraint system components must never be
replaced with any substitutes. These fasteners have
special coatings and are specifically designed for
the restraint system. Any time a new fastener is
needed, replace it with the correct fasteners pro-
vided in the service package or specified in the
DaimlerChrysler Mopar Parts Catalog.
WARNING: To avoid personal injury or death, when
a steering column has an airbag unit attached,
never place the column on the floor or any other
surface with the steering wheel or airbag unit face
down.
DIAGNOSIS AND TESTING - SUPPLEMENTAL
RESTRAINT SYSTEM
Proper diagnosis and testing of the supplemental
restraint system components or the Airbag Control
Module (ACM), initialization of the ACM, as well as
the retrieval or erasure of a Diagnostic Trouble Code
(DTC) from the ACM requires the use of a DRBIIIt
scan tool. Refer to the appropriate diagnostic infor-
mation.
WARNING: To avoid personal injury or death, on
vehicles equipped with airbags, disable the supple-
mental restraint system before attempting any
steering wheel, steering column, airbag, seat belt
tensioner, impact sensor, or instrument panel com-
ponent diagnosis or service. Disconnect and isolate
the battery negative (ground) cable, then wait two
minutes for the system capacitor to discharge
before performing further diagnosis or service. This
is the only sure way to disable the supplemental
restraint system. Failure to take the proper precau-
tions could result in accidental airbag deployment.
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MERCEDES-BENZ SPRINTER 2006 Service Manual STANDARD PROCEDURE
STANDARD PROCEDURE - HANDLING NON -
DEPLOYED SUPPLEMENTAL RESTRAINTS
At no time should any source of electricity be per-
mitted near the inflator on the back of a non-de-
ployed air

STANDARD PROCEDURE
STANDARD PROCEDURE - HANDLING NON -
DEPLOYED SUPPLEMENTAL RESTRAINTS
At no time should any source of electricity be per-
mitted near the inflator on the back of a non-de-
ployed airbag or seat belt tensioner. When carrying a
non-deployed airbag, the trim cover or airbag cushion
side of the unit should be pointed away from the
body to minimize injury in the event of an accidental
deployment. If the airbag unit is placed on a bench or
any other surface, the trim cover or airbag cushion
side of the unit should be face up to minimize move-
ment in the event of an accidental deployment. When
handling a non-deployed seat belt tensioner, take
proper care to keep fingers out from under the
retractor cover and away from the seat belt webbing
where it exits from the retractor cover. In addition,
the supplemental restraint system should be dis-
armed whenever any steering wheel, steering col-
umn, seat belt tensioner, airbag, impact sensor, or
instrument panel components require diagnosis or
service. Failure to observe this warning could result
in accidental deployment and possible personal
injury.
All damaged, faulty or non-deployed airbags and
seat belt tensioners which are replaced on vehicles
are to be handled and disposed of properly. If an air-
bag or seat belt tensioner unit is faulty or damaged
and non-deployed, refer to the Hazardous Substance
Control System for proper disposal. Dispose of all
non-deployed and deployed airbags and seat belt ten-
sioners in a manner consistent with state, provincial,
local and federal regulations.
SUPPLEMENTAL RESTRAINT STORAGE
Airbags and seat belt tensioners must be stored in
their original, special container until they are used
for service. Also, they must be stored in a clean, dry
environment; away from sources of extreme heat,
sparks, and high electrical energy. Always place or
store any airbag on a surface with its trim cover or
airbag cushion side facing up, to minimize movement
in case of an accidental deployment.
STANDARD PROCEDURE - SERVICE AFTER A
SUPPLEMENTAL RESTRAINT DEPLOYMENT
Any vehicle which is to be returned to use follow-
ing a supplemental restraint deployment, must have
the deployed restraints replaced. In addition, if the
driver airbag has been deployed, the clockspring and
the steering wheel must be replaced. If the passenger
airbag has been deployed, the instrument panel must
be replaced. The seat belt tensioners are deployed by
the same signal that deploys the driver and passen-
ger airbags and must also be replaced if either front
airbag has been deployed. These components are notintended for reuse and will be damaged or weakened
as a result of a supplemental restraint deployment,
which may or may not be obvious during a visual
inspection.
It is also critical that the mounting surfaces and/or
mounting brackets for the Airbag Control Module
(ACM) and the side impact sensors be closely
inspected and restored to their original conditions fol-
lowing any vehicle impact damage. Because the ACM
and each impact sensor are used by the supplemental
restraint system to monitor or confirm the direction
and severity of a vehicle impact, improper orientation
or insecure fastening of these components may cause
airbags not to deploy when required, or to deploy
when not required.
All other vehicle components should be closely
inspected following any supplemental restraint
deployment, but are to be replaced only as required
by the extent of the visible damage incurred.
CLEANUP PROCEDURE
Following a supplemental restraint deployment,
the vehicle interior will contain a powdery residue.
This residue consists primarily of harmless particu-
late by-products of the small pyrotechnic charge that
initiates the propellant used to deploy a supplemen-
tal restraint. However, this residue may also contain
traces of sodium hydroxide powder, a chemical
by-product of the propellant material that is used to
generate the inert gas that inflates the airbag. Since
sodium hydroxide powder can irritate the skin, eyes,
nose, or throat, be certain to wear safety glasses,
rubber gloves, and a long-sleeved shirt during
cleanup (Fig. 3).
WARNING: To avoid personal injury or death, if you
experience skin irritation during cleanup, run cool
water over the affected area. Also, if you experience
irritation of the nose or throat, exit the vehicle for
fresh air until the irritation ceases. If irritation con-
tinues, see a physician.
Fig. 3 Wear Safety Glasses and Rubber Gloves -
Typical
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MERCEDES-BENZ SPRINTER 2006 Service Manual (1) Begin the cleanup by using a vacuum cleaner
to remove any residual powder from the vehicle inte-
rior. Clean from outside the vehicle and work your
way inside, so that you avoid kneeling or sittin

(1) Begin the cleanup by using a vacuum cleaner
to remove any residual powder from the vehicle inte-
rior. Clean from outside the vehicle and work your
way inside, so that you avoid kneeling or sitting on a
non-cleaned area.
(2) Be certain to vacuum the heater and air condi-
tioning outlets as well (Fig. 4). Run the heater and
air conditioner blower on the lowest speed setting
and vacuum any powder expelled from the outlets.
CAUTION: All damaged, faulty, or non-deployed
supplemental restraints which are replaced on vehi-
cles are to be handled and disposed of properly. If
an airbag unit or seat belt tensioner unit is faulty or
damaged and non-deployed, refer to the Hazardous
Substance Control System for proper disposal. Be
certain to dispose of all non-deployed and deployed
supplemental restraints in a manner consistent with
state, provincial, local and federal regulations.
(3) Next, remove the deployed supplemental
restraints from the vehicle. Refer to the appropriate
service removal procedures.
(4) You may need to vacuum the interior of the
vehicle a second time to recover all of the powder.
STANDARD PROCEDURE - VERIFICATION TEST
The following procedure should be performed using
a diagnostic scan tool to verify proper supplemental
restraint system operation following the service or
replacement of any supplemental restraint system
component.
WARNING: To avoid personal injury or death, on
vehicles equipped with airbags, disable the supple-
mental restraint system before attempting any
steering wheel, steering column, airbag, seat belt
tensioner, impact sensor, or instrument panel com-
ponent diagnosis or service. Disconnect and isolate
the battery negative (ground) cable, then wait two
minutes for the system capacitor to dischargebefore performing further diagnosis or service. This
is the only sure way to disable the supplemental
restraint system. Failure to take the proper precau-
tions could result in accidental airbag deployment.
(1) During the following test, the battery negative
cable remains disconnected and isolated, as it was
during the supplemental restraint system component
removal and installation procedures.
(2) Be certain that the diagnostic scan tool con-
tains the latest version of the proper diagnostic soft-
ware. Connect the diagnostic to the 16-way Data
Link Connector (DLC). The DLC is located on the
dash panel beneath the driver side lower edge of the
instrument panel, outboard of the steering column
(Fig. 5).
(3) Turn the ignition switch to the On position and
exit the vehicle with the diagnostic scan tool.
(4) Check to be certain that nobody is in the vehi-
cle, then reconnect the battery negative cable.
(5) Using the diagnostic, read and record the
active (current) Diagnostic Trouble Code (DTC) data.
(6) Next, use the diagnostic to read and record any
stored (historical) DTC data.
(7) If any DTC is found in Step 5 or Step 6, refer
to the appropriate diagnostic information.
(8) Use the diagnostic to erase the stored DTC
data. If any problems remain, the stored DTC data
will not erase. Refer to the appropriate diagnostic
information to diagnose any stored DTC that will not
erase. If the stored DTC information is successfully
erased, go to Step 9.
(9) Turn the ignition switch to the Off position for
about fifteen seconds, and then back to the On posi-
tion. Observe the airbag indicator in the instrument
cluster. It should illuminate for four seconds, and
then go out. This indicates that the supplemental
Fig. 4 Vacuum Heater and A/C Outlets - Typical
Fig. 5 16-Way Data Link Connector
1 - BOTTOM OF INSTRUMENT PANEL
2 - CONNECTOR COVER
3 - 16-WAY DATA LINK CONNECTOR
4 - DASH PANEL
5 - INSIDE HOOD RELEASE LEVER
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MERCEDES-BENZ SPRINTER 2006 Service Manual restraint system is functioning normally and that the
repairs are complete. If the airbag indicator fails to
light, or lights and stays on, there is still an active
supplemental restraint system fault

restraint system is functioning normally and that the
repairs are complete. If the airbag indicator fails to
light, or lights and stays on, there is still an active
supplemental restraint system fault or malfunction.
Refer to the appropriate diagnostic information to
diagnose the problem.
NOTE: If the Airbag Control Module (ACM) has been
replaced with a new unit, it will be necessary to ini-
tialize the new ACM. In order to function properly,
the ACM must be programmed for the correct stan-
dard and optional supplemental restraint system
components installed in the vehicle. To initialize the
ACM, a diagnostic scan tool is required. Refer to
the appropriate diagnostic information.
AIRBAG CONTROL MODULE
DESCRIPTION
The Airbag Control Module (ACM) is secured with
three screws to the top mounting surface of a
stamped steel bracket that is welded onto the floor
panel within the seat riser underneath the driver
side front seat in the passenger compartment of the
vehicle (Fig. 6). A molded plastic protective cover is
installed over the ACM and secured with integral
snap features to a flat metal base plate sandwiched
between the bottom of the ACM and the mounting
bracket on the floor panel (Fig. 7). This cover is
designed to shield the ACM and its wire harness con-
nection from other electrical components and wiring
located within the seat riser area beneath the driver
seat, and must always be reinstalled following ser-
vice removal.Concealed within a hollow in the center of the die
cast aluminum ACM housing is the electronic cir-
cuitry of the ACM which includes a microprocessor,
an electronic impact sensor, an electronic safing sen-
sor, and an energy storage capacitor. A stamped
metal cover plate is permanently secured to the bot-
tom of the ACM housing to enclose and protect the
internal electronic circuitry and components.
An arrow printed on a label on the top of the ACM
housing near the rear provides a visual verification
of the proper orientation of the unit, and should
always be pointed toward the front of the vehicle.
The ACM housing has integral mounting flanges on
three corners. A molded plastic electrical connector
receptacle containing numerous terminal pins is inte-
gral to the left facing side of the ACM housing. These
terminal pins connect the ACM to the vehicle electri-
cal system through a dedicated take out and connec-
tor of the vehicle wire harness.
The impact sensor internal to the ACM are cali-
brated for the specific vehicle, and are only serviced
as a unit with the ACM. In addition, the ACM must
be electronically programmed for the correct stan-
dard and optional supplemental restraint system
components installed in the vehicle. The ACM cannot
be repaired or adjusted and, if damaged or faulty, it
must be replaced.
OPERATION
The microprocessor in the Airbag Control Module
(ACM) contains the supplemental restraint system
logic circuits and controls all of the supplemental
restraint system components. The ACM uses
On-Board Diagnostics (OBD) and can communicate
with a diagnostic scan tool using a diagnostic Serial
Fig. 6 Airbag Control Module
1 - AIRBAG CONTROL MODULE
2 - LABEL
3 - ORIENTATION ARROW
4 - CONNECTOR RECEPTACLE
Fig. 7 ACM Bracket
1 - ACM BRACKET
2 - SEAT RISER
3 - EYELET TERMINAL
4 - ACM CONNECTOR
5 - FLOOR PANEL
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MERCEDES-BENZ SPRINTER 2006 Service Manual Communication Interface (SCI) data bus line for sup-
plemental restraint system programming or diagno-
sis and testing through the 16-way Data Link
Connector (DLC) located on the dash panel below the

Communication Interface (SCI) data bus line for sup-
plemental restraint system programming or diagno-
sis and testing through the 16-way Data Link
Connector (DLC) located on the dash panel below the
driver side end of the instrument panel. A hard wired
output from the ACM is used for control of the airbag
indicator in the ElectroMechanical Instrument Clus-
ter (EMIC). (Refer to 8 - ELECTRICAL/INSTRU-
MENT CLUSTER/AIRBAG INDICATOR -
OPERATION).
The ACM microprocessor continuously monitors all
of the supplemental restraint system electrical cir-
cuits to determine the system readiness. If the ACM
detects a monitored system fault, it sets an appropri-
ate Diagnostic Trouble Code (DTC) and sends an out-
put to the EMIC to turn on the airbag indicator. The
ACM illuminates the indicator for about four seconds
each time the ignition switch is turned to the On
position as a bulb test. If the indicator remains illu-
minated for about ten seconds after the ignition
switch is turned to the On position, the ACM has
detected a non-critical fault that poses no danger to
the vehicle occupants. If the airbag indicator illumi-
nates solid (not flashing) while driving or stays on
longer than ten seconds following the bulb test, the
ACM has detected a critical fault that may cause the
airbags not to deploy when required or to deploy
when not required. An active fault only remains for
the duration of the fault, or in some cases, for the
duration of the current ignition switch cycle, while a
stored fault causes a DTC to be stored in memory by
the ACM.
The ACM receives battery current through a fused
ignition switch output circuit. The ACM receives
ground through a ground circuit and take out of the
vehicle wire harness. This take out has an eyelet ter-
minal connector secured by a nut to a ground stud on
the floor panel directly below the ACM within the
driver side seat riser. A case ground is also provided
for the ACM through a ground circuit and eyelet ter-
minal connector secured under the left rear ACM
mounting screw. These connections allow the ACM to
be operational whenever the ignition switch is in the
On position.
The ACM also contains an energy-storage capaci-
tor. When the ignition switch is in the On position,
this capacitor is continually being charged with
enough electrical energy to deploy the supplemental
restraint components for up to one second following a
battery disconnect or failure. The purpose of the
capacitor is to provide backup supplemental restraint
system protection in case there is a loss of battery
current supply to the ACM during an impact.
Two sensors are contained within the ACM, an
electronic impact sensor and a safing sensor. These
electronic sensors are accelerometers that sense the
rate of vehicle deceleration, which provide verifica-
tion of the direction and severity of an impact. Onmodels equipped with optional side curtain airbags,
the ACM also monitors inputs from two remote side
impact sensors located within the left and right front
door step wells to control deployment of the side cur-
tain airbag units.
The safing sensor is an electronic accelerometer
sensor within the ACM that provides an additional
logic input to the ACM microprocessor. The safing
sensor is used to verify the need for a supplemental
restraint deployment by detecting impact energy of a
lesser magnitude than that of the primary electronic
impact sensors, and must exceed a safing threshold
in order for the airbags to deploy. Vehicles equipped
with optional side curtain airbags feature a second
safing sensor within the ACM to provide confirma-
tion to the ACM microprocessor of side impact forces.
This second safing sensor is a bi-directional unit that
detects impact forces from either side of the vehicle.
Pre-programmed decision algorithms in the ACM
microprocessor determine when the deceleration rate
as signaled by the impact sensors and the safing sen-
sors indicate an impact that is severe enough to
require supplemental restraint system protection.
When the programmed conditions are met, the ACM
sends the proper electrical signals to deploy the front
airbags and seat belt tensioners and, if the vehicle is
so equipped, either side curtain airbag unit.
The ACM also provides a hard wired electrical
crash signal output following a supplemental
restraint deployment event. This output is used to
signal other electronic modules in the vehicle to pro-
vide their enhanced accident response features,
which include automatically disabling the engine
from running and unlocking all of the doors. How-
ever, these responses are each dependent upon the
circuits, components, and modules controlling these
features remaining intact from collateral damage
incurred during the vehicle impact.
A single ACM is used for all variations of the sup-
plemental restraint system available in this vehicle.
This ACM is programmable and in order to function
properly it must be programmed for the correct vehi-
cle supplemental restraint system equipment using
an initialization procedure. The initialization proce-
dure requires the use of a diagnostic scan tool. Refer
to the appropriate diagnostic information. The hard
wired inputs and outputs for the ACM may be diag-
nosed and tested using conventional diagnostic tools
and procedures. However, conventional diagnostic
methods will not prove conclusive in the diagnosis of
the ACM or the supplemental restraint system. The
most reliable, efficient, and accurate means to diag-
nose the ACM or the supplemental restraint system
requires the use of a diagnostic scan tool. Refer to
the appropriate diagnostic information.
VARESTRAINTS 8O - 9

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