1997 MERCEDES-BENZ ML320 ECO mode

AIR BAG RESTRAINT SYSTEM
1998 AIR BAG RESTRAINT SYSTEMS Mercedes-Benz
DESCRIPTION & OPERATION
All models are equipped with Supplemental Restraint System (SRS). The main components of SRS are a driver
air bag module, passenger air bag module, control unit, SRS warning light, driver knee bolster, passenger knee
bolster, and Emergency Tensioning Retractor (ETR) seat belt assembly. Additionally, all vehicles provide
driver-side and passenger-side impact protection by side air bags which are mounted in the driver-side and
passenger-side doors. Each of the door mounted side air bags utilize sensors which recognize lateral
acceleration durin
g side impact and signal this to the control module. See Fig. 1. NOTE: Information on ML320 is not available. For WIRING DIAGRAMS, See Fig. 32
.
WARNING:To avoid injury from accidental air bag deployment, read and carefully
follow all WARNINGS and SERVICE PRECAUTIONS
.

1998 Mercedes-Benz ML320
AIR BAG RESTRAINT SYSTEM 1998 AIR BAG RESTRAINT SYSTEMS Mercedes-Benz

1998 Mercedes-Benz ML320
AIR BAG RESTRAINT SYSTEM 1998 AIR BAG RESTRAINT SYSTEMS Mercedes-Benz
me
Saturday, October 02, 2010 3:33:13 PMPage 1 © 2006 Mitchell Repair Information Company, LLC.
me
Saturday, October 02, 2010 3:33:18 PMPage 1 © 2006 Mitchell Repair Information Company, LLC.

Fig. 1: Locating Restraint System Components (E Class Shown; Others Are Similar)
Courtesy of MERCEDES-BENZ OF NORTH AMERICA
Both SRS and ETR are electronically activated by a single control unit if a moderately severe to severe frontal
collision occurs. There are 2 thresholds which must be exceeded to trigger an ETR action, air bag deployment,
or both. If a moderately severe frontal collision occurs exceeding first triggering threshold where protection
from safety belt is sufficient, only Emergency Tensioning Retractor (ETR) is activated if safety belt is buckled.
If a moderately severe frontal collision occurs exceeding first triggering threshold where protection from safety
belt is sufficient, but safety belt is not buckled, air bag is deployed and EAR is not activated.
If a severe frontal collision occurs exceeding second triggering threshold where protection from safety belt is
insufficient, air bag is deployed. EAR is activated if safety belt is buckled. If safety belt is not buckled, ETR is
not activated when second triggering threshold is reached. Passenger air bag will deploy even if passenger seat
is not occupied when a triggering threshold is exceeded. If during a severe frontal collision the power supply is
interrupted, the driver and passenger air bag can still be deployed, but ETR cannot be activated.
The side air bag on the driver-side deploys whenever the driver-side air bag module is deployed and when there
is a substantial side impact crash. The air bag on the passenger-side will activate only when a sensor (Occupied
Seat Recognition Sensor) in the passenger seat sends a signal to the control module that the passenger-side seat
is occupied. During a collision, the side air bag will then deploy.
SERVICING
SRS AIR BAG label on driver-side door latch post indicates SRS replacement date for driver and passenger air
bag units. All SRS components must be thoroughly inspected, including wiring harness. Before component
replacement, check for SRS fault codes by performing system operation check. See SYSTEM OPERATION
CHECK . SRS service life is 10 years from manufactured date, or 10 years from SRS replacement date after
accident related repairs are completed.
POST-COLLISION INSPECTION
When a vehicle has been involved in a collision, certain components of the passive restraint system must be
inspected or replaced. See PASSIVE RESTRAINT SYSTEM INSPECTION article in the GENERAL
INFORMATION section for post-collision inspection information.
ADJUSTMENTS
If fixing screws were not used during clockspring removal or clockspring was rotated during removal, turn
clockspring clockwise until resistance is detectable. Turn clockspring counterclockwise 2-2.5 turns until fixing
screws can be unscrewed holding clockspring in this position.
DISPOSAL PROCEDURES
WARNING:An undeployed air bag module or ETR should never be disposed of
without first being deployed. See SCRAPPED VEHICLE
. If deployment is
not possible, contact vehicle manufacturer for further instructions.

1998 Mercedes-Benz ML320
AIR BAG RESTRAINT SYSTEM 1998 AIR BAG RESTRAINT SYSTEMS Mercedes-Benz
me
Saturday, October 02, 2010 3:33:13 PMPage 3 © 2006 Mitchell Repair Information Company, LLC.

with HHT connected to DLC and ignition key removed. Remove driver-side air bag module. Disconnect
driver-side air bag module squib connector R12/3. Connect Resistance Substitution Unit (124 589 09 63)
to driver-side air bag module squib connector (harness side). Set resistance substitution unit to 2 ohms.
Turn ignition key to position "2". Read NOMINAL VALUE/HHT DISPLAY column. If HHT displays a
check, replace driver-side air bag module. If HHT displays an "F", go to step 3.2.
Read TEST CONNECTION (NOT FOR HHT) column. Horn/air bag clockspring connector A45x1,
terminals No. 1 and 2 are identified. Read TEST CONDITION column. Test circuit with HHT connected
to DLC. Remove ignition key. Connect Resistance Substitution Unit (124 589 09 63 00) to horn/air bag
clockspring connector A45x1. Set resistance substitution unit to 2 ohms. Read NOMINAL VALUE/HHT
DISPLAY column. If HHT displays a check, check horn/air bag clockspring for continuity. Replace
horn/air bag clockspring as necessary. If HHT displays an "F", go to step 3.4.
MODEL IDENTIFICATION
COMPONENT IDENTIFICATION
DIAGNOSTIC TESTS NOTE: Some testing is identified by model number. To identify models by model
number see MODEL IDENTIFICATION
table.
Model NumberModel
129SL Class
140S Class
170SLK 230
202C Class
208CLK 320
210E Class
ComponentManufacturer's Designation
A45Horn/Air Bag Clockspring
A53Driver-Side Air Bag Sensor
A54Passenger-Side Air Bag Sensor
B41/1Passenger-Side Seat Occupied Recognition Sensor
N2/2Control Module
R12/1Driver-Side ETR Squib Connector
R12/2Passenger-Side ETR Squib Connector
R12/3Driver-Side Air Bag Squib Connector
R12/8Passenger-Side Air Bag Squib Connector
R12/9Side Air Bag (Driver-Side)Squib Connector
R12/10Side Air Bag (Passenger-Side) Squib Connector
S68/3Driver-Side Belt Buckle Switch
S68/4Passenger-Side Belt Buckle Switch
W26Control Module Ground
X11/4Data Link Connector

1998 Mercedes-Benz ML320
AIR BAG RESTRAINT SYSTEM 1998 AIR BAG RESTRAINT SYSTEMS Mercedes-Benz
me
Saturday, October 02, 2010 3:33:14 PMPage 20 © 2006 Mitchell Repair Information Company, LLC.

7 IntroductionProduct information
Kindly observe the following in your own best interest:
We recommend using Mercedes-Benz original parts as well as conversion parts and accessories
explicitly approved by us for your vehicle model.
We have tested these parts to determine their reliability, safety and their special
suitability for Mercedes-Benz vehicles.
We are unable to make an assessment for other products and therefore cannot be held responsible
for them, even if in individual cases an official approval or authorization by governmental or other
agencies should exist. Use of such parts and accessories could adversely affect the safety,
performance or reliability of your vehicle. Please do not use them.
Mercedes-Benz original parts as well as conversion parts and accessories approved by us are available
at your authorized Mercedes-Benz Light Truck Center where you will receive comprehensive information, also on
permissible technical modifications, and where proper installation will be performed.

36 Tow-away protection
Te ch n ica l
data Instruments
and controlsOperationDrivingInstrument
cluster displayPractical hints Car care Index
Tow-away alarm and glass breakage sensor
The switch is located in the overhead console.
The tow-away alarm and glass breakage sensor are part
of the antitheft alarm system.
Once the alarm system has been armed, the turn signal
lamps will flash rapidly and the horn will sound when
someone attempts to raise the vehicle, or breaks a
window and reaches into the passenger compartment.The alarm will last approximately 3 minutes in the form
of rapidly flashing turn signal lamps. At the same time
the horn will sound for approximately 30 seconds. The
alarm will stay on even if the vehicle is immediately
lowered.
If the alarm stays on for more than 20 seconds, an
emergency call is initiated automatically. See Tele Aid
on page 148.
To prevent triggering the tow-away alarm feature, switch
off the tow-away alarm and glass breakage sensor before
towing the vehicle, or when parking on a surface subject
to movement, such as a ferry or auto train.
To do so, turn key in steering lock to position 1, then
return it to position 0 and remove key from steering
lock.
Within 30 seconds, push left or right button. (On
vehicles equipped with optional trip computer, push
RESET or MODE button, display shows OFF.)
Exit vehicle, and lock vehicle with remote control.
The tow-away alarm and glass breakage sensor remain
switched off until the key is inserted in steering lock
and turned to position 1.

40 Seats
Te ch n ica l
data Instruments
and controlsOperationDrivingInstrument
cluster displayPractical hints Car care Index
Power seats (standard; optional on model ML 320)
The slide switches are located on the entry side of each
front seat base.
Turn key in steering lock to position 1 or 2 (with the
driver’s or passenger’s door open, the power seats can
also be operated with the key removed or in steering
lock position 0).We recommend to adjust the power seat in the following
order:
1Seat, up / down
Press the switch (up/down direction) until
comfortable seating position with still sufficient
headroom is reached.
2Seat adjustment, fore / aft
Press the switch (fore / aft direction) until a
comfortable seating position is reached that still
allows you to reach the accelerator / brake pedal
safely. The position should be as far rearward as
possible, consistent with ability to properly operate
controls.
3Seat cushion tilt
Press the switch in the direction of the arrow until
your legs are lightly supported.
4Backrest tilt
Press the switch in the direction of the arrow until
your arms are slightly angled when holding the
steering wheel.

42 Seats
Te ch n ica l
data Instruments
and controlsOperationDrivingInstrument
cluster displayPractical hints Car care Index
Memory storing and recalling
(optional on model ML 320 and ML 430)
5Memory button
6Position buttonsStoring
Three sets of seat positions may be programmed into
memory. After the seat is positioned, push memory
button (5), release, and within 3 seconds push position
button “1”. A second and third set of positions for the
same seat can be programmed into memory by pushing
first memory button (5) and then position button “2”,
respectively “3”.
Recalling
To recall a seat position, push and hold one of the
position buttons “1”, “2” or “3” until seat movement has
stopped. The seat movement stops when the respective
position button is released.
Caution!
Do not operate the power seats using the memory
button if the seat backrest is in an excessively reclined
position. Doing so could cause damage to front or rear
seats.
First move the backrest to an upright position.

58 Restraint systems
Te ch n ica l
data Instruments
and controlsOperationDrivingInstrument
cluster displayPractical hints Car care Index
out after approximately 5 seconds; after the lamp goes
out, the system continues to monitor the components
and circuitry of the airbag system and will indicate a
malfunction by coming on again. If the lamp does not
come on at all or if it fails to extinguish after
approximately 5 seconds or if it comes on thereafter,
a malfunction in the system has been detected.
The following system components are monitored or
undergo a self-check: crash-sensor(s), airbag ignition
circuits, front seat belt buckles, emergency tensioning
retractors, seat sensor.
Initially, when the key is turned from steering lock
position 0 to positions 1 or 2, malfunctions in the
crash-sensor are detected and indicated (the “SRS”
indicator lamp stays on longer than 5 seconds or does
not come on).
Have the system checked at your authorized
Mercedes-Benz Light Truck Center immediately.In the operational mode, after the indicator lamp has
gone out following the initial check, interruptions or
short circuits in the airbag ignition circuit and in the
driver and front passenger seat belt buckle harnesses,
and low voltage in the entire system are detected and
indicated.
Wa r n i n g !
In the event a malfunction of the “SRS” is indicated
as outlined above, the “SRS” may not be
operational. For your safety, we strongly
recommend that you visit an authorized
Mercedes-Benz Light Truck Center immediately to
have the system checked; otherwise the “SRS” may
not be activated when needed in an accident, which
could result in serious or fatal injury, or it might
deploy unexpectedly and unnecessarily which
could also result in injury.