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. |
|
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