ECU MERCEDES-BENZ SPRINTER 2006 Service Manual

BULB SPECIFICATIONS
LAMP BULB
Cargo/Dome Lamp K - 12V 18W
Dome/Reading Lamp K - 12V 10W
Dome Lamp w/Intrusion
SensorK - 12V 6W
Entry/Exit Lamp W5W - 12V 5W
ASH RECEIVER / CIGAR
LIGHTER LAMP UNIT
REMOVAL
An ash receiver/cigar lighter lamp unit is optional
equipment on this model (Fig. 1). The bulb and bulb
holder are secured by an integral mount to the out-
side of the cigar lighter halo ring, and serves to illu-
minate both the translucent halo ring and the ash
receiver. A small lens that is snap-fit into the inboard
side of the ash receiver bin allows light from the
lamp on the halo ring to also illuminate the ash
receiver. The ash receiver/cigar lighter lamp is ser-
viced only as a unit with the ash receiver housing
and cigar lighter receptacle. If the lamp is faulty or
damaged, the entire ash receiver housing and cigar
lighter receptacle unit must be replaced. (Refer to 23
- BODY/INSTRUMENT PANEL/ASH RECEIVER -
REMOVAL).
INSTALLATION
An ash receiver/cigar lighter lamp unit is optional
equipment on this model (Fig. 1). The bulb and bulb
holder are secured by an integral mount to the out-side of the cigar lighter halo ring, and serves to illu-
minate both the translucent halo ring and the ash
receiver. A small lens that is snap-fit into the inboard
side of the ash receiver bin allows light from the
lamp on the halo ring to also illuminate the ash
receiver. The ash receiver/cigar lighter lamp is ser-
viced only as a unit with the ash receiver housing
and cigar lighter receptacle. If the lamp is faulty or
damaged, the entire ash receiver housing and cigar
lighter receptacle unit must be replaced. (Refer to 23
- BODY/INSTRUMENT PANEL/ASH RECEIVER -
INSTALLATION).
CARGO / DOME LAMP BULB
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the cargo/dome lamp unit from its
mounting location, but do not disconnect the vehicle
wire harness from the lamp connector receptacle.
(Refer to 8 - ELECTRICAL/LAMPS/LIGHTING -
INTERIOR/CARGO/DOME LAMP UNIT -
REMOVAL).
(3) Grasp the lamp housing in one hand and care-
fully pull the bulb out of the bulb holder with the
other hand (Fig. 2).
INSTALLATION
(1) Grasp the cargo/dome lamp housing in one
hand and carefully insert the bulb into the bulb
holder with the other hand (Fig. 2).
(2) Reinstall the cargo/dome lamp unit into its
mounting location. (Refer to 8 - ELECTRICAL/
LAMPS/LIGHTING - INTERIOR/CARGO/DOME
LAMP UNIT - INSTALLATION).
(3) Reconnect the battery negative cable.
Fig. 1 Ash Receiver/Cigar Lighter Lamp Unit
1 - CIGAR LIGHTER
2 - HALO RING
3 - LENS
4 - LAMP UNIT (BIN REMOVED)
5 - ASH RECEIVER BIN
6 - ASH RECEIVER
Fig. 2 Cargo/Dome Lamp Bulb Remove/Install
1 - LAMP HOUSING
2 - BULB
3 - CONNECTOR RECEPTACLE
8L - 30 LAMPS/LIGHTING - INTERIORVA

(3) Pull the dome lamp/intrusion sensor unit from
its mounting location far enough to access and dis-
connect the vehicle wire harness from the lamp con-
nector receptacle.
(4) Remove the dome lamp/intrusion sensor unit
from its mounting location.
INSTALLATION
(1) Position the dome lamp/intrusion sensor unit to
its mounting location (Fig. 8).
(2) Reconnect the vehicle wire harness connector
to the dome lamp/intrusion sensor unit connector
receptacle.
(3) Position the edge of the dome lamp/intrusion
sensor unit housing opposite from the retainer clip
into the mounting hole.
(4) Push firmly and evenly on the notched edge of
the dome lamp/intrusion sensor unit housing until
the retainer clip latches into place.
(5) Reconnect the battery negative cable.
DOOR JAMB SWITCH
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Open the door and remove the screw that
secures the door jamb switch to the hinge pillar of
the door opening (Fig. 9).(3) Pull the door jamb switch away from the
mounting hole in the pillar far enough to access and
disconnect the vehicle wire harness connector from
the back of the switch.
INSTALLATION
(1) Position the door jamb switch close enough to
the mounting hole in the hinge pillar of the door
opening to reconnect the vehicle wire harness connec-
tor to the back of the switch.
(2) Position the door jamb switch into the mount-
ing hole in the hinge pillar (Fig. 9).
(3) Install and tighten the screw that secures the
door jamb switch to the hinge pillar.
(4) Reconnect the battery negative cable.
ENTRY / EXIT LAMP BULB
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the entry/exit lamp unit from its
mounting location. (Refer to 8 - ELECTRICAL/
LAMPS/LIGHTING - INTERIOR/ENTRY/EXIT
LAMP UNIT - REMOVAL).
(3) Grasp the lamp housing firmly in one hand,
then rotate the bulb holder counterclockwise and pull
it straight out from the housing with the other hand
(Fig. 10).
Fig. 8 Dome Lamp/Intrusion Sensor Unit Remove/
Install
1 - NOTCH
2 - SENSOR (3)
3 - HOUSING
4 - SWITCH (2)
Fig. 9 Door Jamb Switch Remove/Install
1 - DOOR JAMB SWITCH
2 - PLUNGER
3 - PILLAR
4 - SCREW
8L - 34 LAMPS/LIGHTING - INTERIORVA

(4) Remove the bulb from the bulb holder.
INSTALLATION
(1) Insert the bulb into the entry/exit lamp bulb
holder (Fig. 10).
(2) Grasp the entry/exit lamp housing firmly in
one hand, then insert the bulb holder into the hous-
ing and rotate it clockwise to lock it in place with the
other hand.
(3) Reinstall the entry/exit lamp unit into its
mounting location. (Refer to 8 - ELECTRICAL/
LAMPS/LIGHTING - INTERIOR/ENTRY/EXIT
LAMP UNIT - INSTALLATION).
(4) Reconnect the battery negative cable.
ENTRY / EXIT LAMP UNIT
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Insert the tip of a small flat-bladed screwdriver
into the notch on one edge of the entry/exit lamp
housing to depress the retainer clip and pull that
edge of the lamp away from its mounting location
(Fig. 11).
(3) Pull the entry/exit lamp unit from its mounting
location far enough to access and disconnect the vehi-
cle wire harness from the lamp connector receptacle.(4) Remove the entry/exit lamp unit from its
mounting location.
INSTALLATION
(1) Position the entry/exit lamp unit to its mount-
ing location.
(2) Reconnect the vehicle wire harness connector
to the entry/exit lamp connector receptacle (Fig. 11).
(3) Position the edge of the entry/exit lamp hous-
ing opposite from the retainer clip into the mounting
hole.
(4) Push firmly and evenly on the notched edge of
the entry/exit lamp housing until the retainer clip
latches into place.
(5) Reconnect the battery negative cable.
TIME DELAY RELAY
REMOVAL
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, or instrument panel component diagno-
sis or service. Disconnect and isolate the battery
negative (ground) cable, then wait two minutes for
the system capacitor to discharge before perform-
ing further diagnosis or service. This is the only
sure way to disable the supplemental restraint sys-
tem. Failure to take the proper precautions could
result in accidental airbag deployment.
(1) Disconnect and isolate the battery negative
cable.
(2) Move the driver side front seat to its most for-
ward position for easiest access to the seat riser
cover panel.
(3) Remove the two screws that secure the cover
panel to the top of the seat riser under the driver
side front seat (Fig. 12).
Fig. 10 Entry/Exit Lamp Bulb Remove/Install
1 - LAMP HOUSING
2 - BULB HOLDER
3 - CONNECTOR
Fig. 11 Entry/Exit Lamp Unit Remove/Install
1 - STEP WELL SCUFF PAD
2 - NOTCH
3 - ENTRY/EXIT LAMP UNIT
VALAMPS/LIGHTING - INTERIOR 8L - 35

(4) Remove the cover panel from the top of the
driver side seat riser.
(5) Remove the time delay relay from its vehicle
wire harness connector by grasping it firmly and
pulling it straight out from the connector within the
driver side seat riser.
INSTALLATION
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, or instrument panel component diagno-
sis or service. Disconnect and isolate the battery
negative (ground) cable, then wait two minutes for
the system capacitor to discharge before perform-
ing further diagnosis or service. This is the only
sure way to disable the supplemental restraint sys-
tem. Failure to take the proper precautions could
result in accidental airbag deployment.
(1) Position the time delay relay to its vehicle wire
harness connector within the driver side seat riser.
(2) Align the time delay relay terminals with the
terminal cavities in the vehicle wire harness connec-
tor.
(3) Push firmly and evenly on the top of the time
delay relay until the terminals are fully seated in the
terminal cavities in the vehicle wire harness connec-
tor.
(4) Position the cover panel onto the top of the
driver side seat riser (Fig. 12).
(5) Install and tighten the two screws that secure
the cover panel to the top of the seat riser under the
driver side front seat. Tighten the screws to 2 N´m
(18 in. lbs.).(6) Move the driver side front seat back to its driv-
ing position.
(7) Reconnect the battery negative cable.
Fig. 12 Seat Riser Cover
1 - DRIVER SEAT BACK
2 - COVER PANEL
3 - SCREW (2)
4 - SEAT RISER
8L - 36 LAMPS/LIGHTING - INTERIORVA

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. Active restraints are those which
require the vehicle occupants to take some action to
employ, such as fastening a seat belt; while passive
restraints require no action by the vehicle occupants
to be employed (Fig. 1).ACTIVE RESTRAINTS
The active restraints for this model include:
²Front Seat Belts- Both outboard front seating
positions are equipped with three-point seat belt sys-
tems employing a lower B-pillar mounted inertia
latch-type retractors, height-adjustable upper B-pil-
lar mounted turning loops, travelling lower seat belt
anchors secured to the outboard seat tracks, and
Fig. 1 Supplemental Restraint System
1 - PASSENGER AIRBAG (OPTIONAL)
2 - SIDE IMPACT SENSOR (2 - WITH OPTIONAL SIDE CURTAIN AIRBAGS ONLY)
3 - DRIVER AIRBAG
4 - AIRBAG CONTROL MODULE
5 - SEAT BELT TENSIONER (DRIVER SIDE - STANDARD, PASSENGER SIDE - OPTIONAL WITH PASSENGER AIRBAG ONLY)
6 - SIDE CURTAIN AIRBAG (2 - OPTIONAL)
8O - 2 RESTRAINTSVA

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
VARESTRAINTS 8O - 3

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
8O - 6 RESTRAINTSVA

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
8O - 8 RESTRAINTSVA

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

REMOVAL
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, never
strike or drop the airbag control module as it can
damage the impact sensor or affect its calibration.
The airbag control module contains the impact sen-
sor, which enables the system to deploy the supple-
mental restraints. If an airbag control module is
accidentally dropped during service, the module
must be scrapped and replaced with a new unit.
Failure to observe this warning could result in acci-
dental, incomplete, or improper supplemental
restraint deployment.
(1) Disconnect and isolate the battery negative
cable. Wait two minutes for the system capacitor to
discharge before further service.
(2) Move the driver side front seat to its most for-
ward position for easiest access to the seat riser
cover panel (Fig. 8).(3) Remove the two screws that secure the cover
panel to the top of the seat riser under the driver
side front seat (Fig. 9).
(4) Remove the cover panel from the top of the
driver side seat riser.
(5) Remove the two screws that secure the control
module bracket to the top of the seat riser under the
driver side front seat (Fig. 10).
Fig. 8 Airbag Control Module Location
1 - DRIVER SEAT
2 - AIRBAG CONTROL MODULE
3 - SEAT RISER
Fig. 9 Seat Riser Cover
1 - DRIVER SEAT BACK
2 - COVER PANEL
3 - SCREW (2)
4 - SEAT RISER
8O - 10 RESTRAINTSVA