Mercedes-Benz ML320. Manual — part 1

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 during 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

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1998 Mercedes-Benz ML320

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

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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

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Several situations may arise requiring some form of disposal action, including:



Scrapping a vehicle containing a deployed air bag module and/or ETR.



Scrapping a vehicle with a live air bag module and/or ETR.



Disposal of a live but electrically faulty air bag module and/or ETR.



Disposal of a deployed air bag module and/or ETR.

DEPLOYED AIR BAG OR ETR

Deployed air bag module and/or ETR unit can be thrown away. None of its components are reusable. Deployed
air bag module is NOT classified as hazardous material.

SCRAPPED VEHICLE

1. Before proceeding, follow service precautions. See SERVICE PRECAUTIONS . Move vehicle

outdoors to a remote area, away from workshop and other personnel. Disconnect and shield negative
battery cable. Open all vehicle windows and doors.

2. Ensure air bag module is secured to steering wheel, and passenger air bag is secured to dash. Ensure ETR

seat belt assemblies are secured to "B" pillars and all seat belt buckles are latched. Remove loose objects
from front seat. DO NOT allow anyone inside vehicle.

3. Disable air bag system. See DISABLING & ACTIVATING AIR BAG SYSTEM . Connect Trigger

Device (126-589-00-90-00) and Adapter Cable (126 589 21 63 00) to SRS system connector (X29/9)
located at passenger footwell area. See Fig. 5 . Move away from vehicle as far as trigger device wiring
will allow.

4. To deploy driver air bag and ETR, turn rotary knob on trigger device to position No. 1. Push battery

check pushbutton and ignition pushbutton simultaneously. Trigger light should illuminate indicating
driver air bag and ETR deployed. If trigger light is illuminated and driver air bag and/or ETR did not
deploy, driver air bag module and/or ETR is faulty. See UNDEPLOYED AIR BAG/ETR .

5. To deploy passenger air bag detonator No. 1, turn rotary knob on trigger device to position No. 2. Push

battery check pushbutton and ignition pushbutton simultaneously. Trigger light should illuminate
indicating passenger air bag detonator No. 1 deployed. If trigger light is illuminated and passenger air bag
detonator No. 1 did not deploy, passenger air bag module is faulty. See UNDEPLOYED AIR
BAG/ETR .

6. To deploy passenger air bag detonator No. 2, turn rotary knob on trigger device to position No. 3. Push

battery check pushbutton and ignition pushbutton simultaneously. Trigger light should illuminate
indicating passenger air bag detonator No. 2 deployed. If trigger light is illuminated and passenger air bag
detonator No. 2 did not deploy, passenger air bag module is faulty. See UNDEPLOYED AIR
BAG/ETR .

WARNING:

An undeployed air bag module and/or ETR seat belt CANNOT be disposed
of without first being deployed. If this is not possible through procedures
outlined below, contact vehicle manufacturer for further instructions.
Perform remote deployment outdoors. Keep personnel at least 20 feet
away.

1998 Mercedes-Benz ML320

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

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