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Volume 5.1

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LOCATION:    16.6 Airbag (AB)   >   12 Diagnosis - Diagnostic Trouble Code (DTC) Memory (driver/passenger-side airbag/side airbag/windowbag)


Diagnosis - Diagnostic Trouble Code (DTC) Memory (driver/passenger-side airbag/side airbag/windowbag)

Preliminary work:
Diagnosis - Function Test 11

Preparation for DTC readout

1. Review 11, 12, 13, 20, 22, 31,
2. Connect Hand-Held Tester (HHT) as per connection diagram, see section 0, and readout DTC memory,
3. Fuses OK,
4. Battery voltage 11 - 14 V.

CAUTION!
Do not connect battery trickle charger.
CAUTION!
Risk of Injury when performing Diagnostic Tests and repairs on components of the SRS system and/or the ETR.
Store both airbags and side airbags with opening surface pointing upward.
Do not expose to temperatures above 100°C.
Interrupt any electrical current from reaching the airbag unit.
Review pages: 11/1 and 11/2

Diagnostic trouble codes (DTC's) can only be read out and erased using the Hand-Held Tester (HHT).


When installing additional accessories, observe harness clearances near SRS sensor lines.

Test equipment; See MBUSA Standard Service Equipment Program

Hand-Held Tester (HHT) 1) See S.I. in groups 58 and 99.
1) Available through the MBUSA Standard Equipment Program.


A current fault is indicated by the DTC being highlighted in black.
Additional detailed information is given with most DTC's, which will indicate possible faults conditions or portions thereof:
> Resistance too great.
< Resistance too low.
- Short circuit to ground (GND)
+ Short circuit to positive (POS).
-//- Open circuit.

Fault frequency and time span of the fault can be read by pressing the key.

Fault frequency:
Faults are noted by frequency of occurrence, i.e.: 5 periodic faults, 5 occurances, eliminated 5 times.

Time span:
The amount of time elapsed since last fault,
or since fault eliminated itself.

Actual values:
Four displays are possible:
, , , .

: Noted values are within the nominal values.
: Noted values are outside the nominal values.
: Seat belt buckle latched, front passenger seat occupied.
: Seat belt buckle not latched, front passenger seat not occupied.

Contrary to the DTC memory, actual values are updated continuously, even during diagnosis, so that, e.g.: by moving components, or connections and wiring harnesses, intermittent failures may be indicated, recognized.

Additional Actual Values:
If so equipped, with Seat Occupied Recognition (SOR) with Automatic Child Seat Recognition (ACSR) the additional information is shown:
Function:
(SOR continues to be active regardless if MB Child seat "Babysafe" is not used or recognized).
Passenger seat:
Child seat:
Facing direction of child seat:


The actual values: SOR/ACSR are updated approx. every 15 seconds.

DTC
Possible cause Hints Test step/Remedy 1)
No communication with HHT Diagnostic line   23 34.0
No fault codes No fault codes recognized. In case of complaint;
Perform Electrical Test: 23
23
ARMIN control module (N2/7)   N2/7
SRS MIL (A1e15)   23 2.0
Voltage supply   23 1.0
Driver airbag squib (R12/3)   23 4.0,
23 3.0
Front passenger AB squib (R12/8)   23 6.0,
23 5.0
Driver ETR squib (R12/1)   23 18.0,
23 17.0
Front passenger ETR squib (R12/2)
  23 20.0,
23 19.0
LR ETR squib (R12/6)   23 24.0,
23 23.0
RR ETR squib (R12/7)   23 26.0,
23 25.0
Left front side airbag squib (R12/20)   23 8.0,
23 7.0
Left rear windowbag squib (R12/22)   23 28.0,
23 27.0
RR side airbag squib (R12/12)   23 12.0,
23 11.0
Right front side airbag squib (R12/21)   23 10.0,
23 9.0
Right rear side airbag squib (R12/23)   23 30.0,
23 29.0
RR side airbag squib (R12/12)   23 14.0,
23 13.0
Left front seat belt buckle switch
(AB/ETR) (S68/3)
  23 21.0
Right front seat belt buckle switch
(AB/ETR) (S68/4)
  23 22.0
Left side airbag sensor (A53/1)   23 15.0
Right side airbag sensor (A54/1)   23 16.0
Front passenger seat occupied recognition with automatic child seat recognition
(ACSR (B48)
  23 31.0
Digital crash output   23 35.0
Analoge crash output   23 36.0
Automatic child seat recognition warning lamp (N72e1) (AIRBAG OFF)   23 33.0
1) Observe Preparation for Test, see 22.