warning MERCEDES-BENZ ML320 1997 Complete Repair Manual

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
.

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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.

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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.

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UNDEPLOYED AIR BAG/ETR
After deploying procedures and/or diagnostic testing have confirmed air bag module and/or ETR is
undeployable, contact vehicle manufacturer for proper disposal instructions.
REMOVAL & INSTALLATION
CLOCKSPRING ASSEMBLY
Removal & Installation
1. Before proceeding, see SERVICE PRECAUTIONS . Disable air bag system. See DISABLING &
ACTIVATING AIR BAG SYSTEM .
2. Remove driver air bag module. See DRIVER
-SIDE AIR BAG MODULE . Remove steering wheel bolt.
Using a puller, remove steering wheel. Disconnect lower clockspring connector. Turn 2 fixing screws
(locating on clockspring) counterclockwise until clockspring cannot be rotated. Remove clockspring
mounting screws as necessary. Disconnect all necessary electrical connectors. Remove clockspring
assembly. To install, reverse removal procedure. Activate air bag system. See DISABLING &
ACTIVATING AIR BAG SYSTEM . Perform system operation check to ensure system is functioning
properly. See SYSTEM OPERATION CHECK
.
CONTROL UNIT
Removal & Installation (C Class)
1. Before proceeding, see SERVICE PRECAUTIONS . Disable air bag system. See DISABLING &
ACTIVATING AIR BAG SYSTEM . Remove ignition key. Remove shift lever cover bezel. Lift shift
lever cover enough to disconnect electrical connector. Remove shift lever cover.
2. Remove storage compartment mounting screws from center console. Remove storage compartment.
Remove ashtray. Disconnect electrical connectors as necessary. Disconnect control module electrical
connector. Remove control module mounting bolts. Remove control module.
3. To install, reverse removal procedure. Ensure control module arrow points to front of vehicle. Set
parameters and program new control module with Hand-Held Tester (965 589 00 01 00). Activate air bag
system. Perform system operation check to ensure system is functioning properly. See SYSTEM
OPERATION CHECK .
Removal & Installation (E Class)
1. Before proceeding, see SERVICE PRECAUTIONS . Disable air bag system. See DISABLING &
ACTIVATING AIR BAG SYSTEM . Remove ignition key. Remove gear shift cover panel. Remove
ashtray and ashtray housing at front of console. Remove radio (if necessary).
2. Remove center console right side cover screws and right side cover. Disconnect electrical connector for
control unit. Remove 2 control unit mounting screws. Remove control unit. WARNING:Failure to follow service precautions may result in air bag deployment and
personal injury. See SERVICE PRECAUTIONS
. After component
replacement, check system operation. See SYSTEM OPERATION CHECK
.

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check to ensure system is functioning properly. See SYSTEM OPERATION CHECK .
Removal & Installation (SLK 230)
1. Before proceeding, see SERVICE PRECAUTIONS . Disable air bag system. See DISABLING &
ACTIVATING AIR BAG SYSTEM . Remove ignition key. Remove top section of instrument panel.
Fold vapor barrier toward front to reveal 2 screws. Disconnect passenger-side air bag module connector.
Remove 4 screws and passenger-side air bag module.
2. To install air bag module, reverse removal procedure. Activate air bag system. Perform system operation
check to ensure system is functioning properly. See SYSTEM OPERATION CHECK
.
SYSTEM OPERATION CHECK
SRS warning light indicates air bag and Emergency Tensioning Retractor (ETR) system readiness. Turn
ignition on. SRS warning light will light, and then go out after approximately 4 seconds indicating system is
functioning properly. If SRS warning light does not light, lights up while driving or lights all the time, there is a
system fault. Repair malfunctioning system. See DIAGNOSIS & TESTING
.
SERVICE PRECAUTIONS
Observe following precautions when working with air bag systems:
When working around steering column components and before any repairs are performed, disable air bag
system. See DISABLING & ACTIVATING AIR BAG SYSTEM
.
Before straightening any damage to body, or before performing electrical arc-welding, disable air bag
system. See DISABLING & ACTIVATING AIR BAG SYSTEM
.
Always wear safety glasses and gloves when handling a deployed air bag module. Air bag module may
contain sodium hydroxide deposits which are irritating to the skin.
DO NOT repair any portion of SRS wiring harness.
Always handle air bag module with trim cover away from your body. Always place air bag module on
workbench with trim cover up, away from loose objects.
DO NOT expose any SRS component to temperatures in excess of 212°F (100°C).
DO NOT expose any SRS component to cleaning agents such as solvents, gasoline, lye, etc.
DO NOT connect Hand-Held Tester (6511 0001 99) to Data Link Connector (DLC) with ignition on.
Damage to HHT may result.
DO NOT connect HHT (6511 0001 99) to vehicle if a battery charger is connected to vehicle battery.
Damage to HHT may result.
DISABLING & ACTIVATING AIR BAG SYSTEM DISABLING SYSTEM
Before proceeding, follow air bag service precautions. See SERVICE PRECAUTIONS
. Turn ignition off.
Disconnect and shield negative battery cable. Remove passenger foot mat. Remove passenger footrest.
Disconnect SRS system connector (X29/9) located at passenger footwell area. See Fig. 5
. System is now
disabled.

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If any part of SRS wiring harness is damaged, DO NOT repair wiring harness, replace complete wiring harness.
TORQUE SPECIFICATIONS
TORQUE SPECIFICATIONS
(1)
DIAGNOSIS & TESTING
Before proceeding, see SERVICE PRECAUTIONS
. The control module is capable of diagnosing airbag
system components and ETR components. If a fault is detected by the control module or system is
malfunctioning, SRS warning light will do one or more of the following:
SRS warning light goes out after 2 minutes. System fault is noted, however occupant protection is not
affected. See RETRIEVING FAULT CODES
.
SRS warning light illuminates continuously. System is faulty which may result in a non deployment or
false deployment. See RETRIEVING FAULT CODES
.
SRS warning light blinks continuously. Control module has been replaced without setting control module
parameters.
RETRIEVING FAULT CODES
1. Check vehicle fuses. Replace any blown fuses as necessary. Ensure vehicle battery voltage is 11 volts or
more. Ensure SRS warning light functions. Turn ignition off. Connect Hand-Held Tester (HHT) (965 589
00 01) to Data Link Connector (DLC).
2. DLC is located in right rear corner of engine compartment. It may be necessary to use Adapter (965 589
00 40 or 965 589 00 50) to connect HHT to DLC. After HHT displays module number and version, press
return key to start diagnosis. Using HHT, follow HHT prompts to retrieve SRS fault codes.
3. HHT will display a 3 digit fault code, and may display additional graphic information. This additional
graphic information will help in diagnosis of fault code. See Fig. 6
. During diagnosis HHT will display 4
different graphic displays informing technician if a test passes or fails, or if seat belt buckle is latched or
not latched. See Fig. 6
.
4. These
graphic displays are displayed as applicable by HHT during testing. See FAULT CODES table.
ApplicationFt. Lbs. (N.m)
Steering Wheel Hub Bolt52-66 (70-90)
INCH Lbs. (N.m)
Driver Air Bag Module Bolts (Torx)44-62 (5-7)
(1)Torque specifications are not available for clockspring assembly, control module or passenger-side
air bag module.
NOTE: After component replacement, perform a system operation check to ensure
proper system operation. See SYSTEM OPERATION CHECK
.
NOTE: Fault codes may only be retrieved using Hand-Held Tester (965 589 00 01) and
Adapter (965 589 00 40 or 965 589 00 50).

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FAULT CODES
Code (Possible Cause)
Go To Test Step (See
Fig.)
00
(SRS Control Module, N2/2)2.0
003
(Voltage Supply Circuit 15R, Low Voltage)1.0
002
(SRS Warning Light, A1e15)11.0
004
(Driver Air Bag Squib, R12/3)3.0, 4.0 (7, 9)
005
(Driver ETR Squib, R12/1)5.0
006
(Passenger ETR Squib, R12/2)7.0
007
(Passenger Air Bag Squib, R12/4)9.0, 10.0 (12, 13)
008
(Side Air Bag Squib, Driver-Side)17.0
009
(Side Air Bag Squib, Passenger- Side)18.0
016
(Driver Belt Switch, S68/3)12.0, 13.0
017
(Passenger Belt Switch, S68/3)14.0, 15.0
018
(Driver Air Bag Harness)19.0
019
(Driver Air Bag Sensor)Replace Sensor
020
(Driver Air Bag Sensor)Replace Sensor
021
(Passenger Air Bag Sensor)20.0
022
(Passenger Air Bag Sensor)Replace Sensor
023
(Passenger Air Bag Sensor)Replace Sensor
024
(Passenger Seat Occupation Signal)21, 22 (21, 22)
025
(Passenger Seat Occupation Signal)21

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CLEARING FAULT CODES
Connect Hand-Held Tester (965 589 00 01) to Data Link Connector (DLC). DLC is located in right rear corner
of engine compartment. It may be necessary to use Adapter (965 589 00 40 or 965 589 00 50) to connect HHT
to DLC. After HHT displays module number and version, press return key to start sequence. Using HHT,
follow HHT prompts to clear SRS fault codes. SRS codes are clear when ignition is turned on and SRS warning
light functions normally. See SYSTEM OPERATION CHECK
.
UNDERSTANDING DIAGNOSTIC CHART INFORMATION
SRS & ETR Diagnosis Chart Column Identification
For example, see Fig. 7
under DIAGNOSTIC TESTS. First column of chart identifies TEST STEP (1.0 for
example). Second column of chart identifies HHT fault code (017, 003 for example). First code in column is for
vehicles without side air bags. Second code in column (when listed) is for vehicles with side air bags only.
Other 5 columns are self-explanatory.
Using SRS & ETR Diagnosis Chart
For reading and understanding fault code diagnosis chart, use the following example: Read test step 3.0
(first column), HHT fault Code 002, 004 (second column). See Fig. 7
. Read TEST SCOPE/HHT
ACTUAL VALUE NO./TEXT column (third column). Driver-side air bag squib connector R12/3 is
being tested. HHT will identify if problem is with too much resistance or not enough resistance in driver-
side air bag squib circuit. Read TEST CONDITION column (fifth column). Test circuit with HHT
connected to DLC, with ignition in position "2". Read NOMINAL VALUE/HHT DISPLAY column
(sixth column). HHT will display a check or an "F". If HHT displays a check, circuit is okay. If HHT
displays an "F", go to step 3.1.
Read TEST CONNECTION (NOT FOR HHT) column (forth column). Driver-Side air bag squib
connector R12/3, terminals No. 1 and 2 are identified. Read TEST CONDITION column. Test circuit
027
(Passenger Seat Occupation Signal)22
032, 033
(Communication Interference)(1)
034
(Digital Crash Output, Harness Fault)(1)
035
(Analog Crash Output, Harness Fault)(1)
036
(Auto Child Seat Recognition Light)22.0, 23.0
(1)Test information is not available.
NOTE: To properly identify components or connectors being tested, see COMPONENT
IDENTIFICATION table.

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Our company and staff congratulate you on the purchase of your new Mercedes-Benz.
Your selection of our product is a demonstration of your trust in our company name. Further, it exemplifies your desire
to own an automobile that will be as easy as possible to operate and provide years of service.
Your Mercedes-Benz represents the efforts of many skilled engineers and craftsmen. To ensure your pleasure of
ownership, and for your safety and that of your passengers, we ask you to make a small investment of your time:
•Please read this manual carefully before putting it aside. Then return it to your vehicle where it will be handy for
your reference.
•Please abide by the recommendations contained in this manual. They are designed to acquaint you with the
operation of your Mercedes-Benz.
•Please abide by the warnings and cautions contained in this manual. They are designed to help improve the safety
of the vehicle operator and occupants.
We extend our best wishes for many miles of safe, pleasurable driving.
DaimlerChrysler AG

1 Contents
IntroductionProduct information .......................... 7
Roadside assistance ......................... 10
Where to find it ................................ 14
Reporting Safety Defects ................ 16Instruments and controlsInstruments and controls ............... 18
Center console .............................. 20
Overhead control panel ............... 21OperationVehicle keys ...................................... 24
Start lock-out .................................... 25
General notes on the
central locking system ............... 26
Central locking system ................... 26
Radio frequency
remote control .............................. 26
Unlocking the liftgate .................. 28
Panic button .................................. 28
Mechanical keys ........................... 29Doors ................................................. 30
Central locking switch .................... 32
Automatic central locking .......... 32
Emergency unlocking in case
of accident ................................... 33
Liftgate .............................................. 34
Antitheft alarm system ................... 35
Tow-away alarm and
glass breakage sensor ............... 36
Seats, front ....................................... 37
Manual seats ................................ 39
Power seats ................................... 40
Head restraint ...............................41
Heated seats ..................................... 44
Seat belts and integrated
restraint system .......................... 46
Seat belts .......................................... 46
Seat belt nonusage
warning system ............................ 47
BabySmart
TM airbag
deactivation system ................... 53
Self-test BabySmart
TM
without special child
seat installed ................................ 53Supplemental restraint
system (SRS) ................................ 54
Emergency tensioning
retractor (ETR) ............................. 55
Airbags .............................................. 56
Safety guidelines for the
seat belt, emergency
tensioning retractor
and airbag ..................................... 63
Infant and child
restraint systems .......................... 65
Adjustable steering wheel .............. 70
Inside rear view mirror .................. 71
Antiglare night position .............. 71
Exterior rear view mirrors ............. 73
Exterior rear view mirror,
electrically folding ....................... 75
Instrument cluster ........................... 76
Indicator lamps in the
instrument cluster ...................... 78
Trip computer ................................... 83
Flexible service system (FSS) ........ 87
Engine oil level indicator ................ 89
Exterior lamp switch ....................... 90