Mercedes-Benz ML320. Manual — part 5

During diagnosis, system values are continuously updated, so by moving components and connections
intermittent failures can be diagnosed. HHT will also display fault frequency and time span.

5. After retrieving fault codes using HHT, carefully observe testing instructions in this article. Some testing

is executed with HHT connected to DLC and some tests are executed with HHT removed from DLC.
Turn ignition off when removing or connecting HHT to DLC.

6. Contact Box (124 589 00 21) with Test Cable (124 589 35 63) is necessary to complete some test steps.

Resistance Substitution Unit (124 589 09 63) is necessary to substitute resistance values for testing
purposes.

Fig. 6: Hand Held Tester Graphic Information
Courtesy of MERCEDES-BENZ OF NORTH AMERICA

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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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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 Number

Model

129

SL Class

140

S Class

170

SLK 230

202

C Class

208

CLK 320

210

E Class

Component

Manufacturer's Designation

A45

Horn/Air Bag Clockspring

A53

Driver-Side Air Bag Sensor

A54

Passenger-Side Air Bag Sensor

B41/1

Passenger-Side Seat Occupied Recognition Sensor

N2/2

Control Module

R12/1

Driver-Side ETR Squib Connector

R12/2

Passenger-Side ETR Squib Connector

R12/3

Driver-Side Air Bag Squib Connector

R12/8

Passenger-Side Air Bag Squib Connector

R12/9

Side Air Bag (Driver-Side)Squib Connector

R12/10

Side Air Bag (Passenger-Side) Squib Connector

S68/3

Driver-Side Belt Buckle Switch

S68/4

Passenger-Side Belt Buckle Switch

W26

Control Module Ground

X11/4

Data Link Connector

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