NHTSA ID Number: 10177544
Manufacturer Communication Number: LI54.21-P-070658
TSB/Document Date: 2020-07-27
Summary
A fixed SRS message is displayed in the instrument cluster. Cause is not safety-relevant and does not affect function of safety systems.
SRS Message Displayed in Instrument Cluster
Topic number
LI54.21-P-070658
Version
4
Function group
54.21 Control units / basic modules
Date
06-04-2020
Validity
A-Class (177)
CLA-Class (118)
GLB-Class (247)
Reason for change
Updated Remedy, Validity and Part Number
Reason for block
Complaint:
A fixed SRS message is displayed in the instrument cluster. Cause is not safety-relevant and does not affect function
of safety systems.
Cause:
Higher resistance values at the SRS control unit connector for various SRS components (squibs, tensioners, pyrofuse, etc.). Complaint vehicles contain the stored fault code "There is an open circuit" for various squibs.
Remedy:
Note: If there are active/current faults or short circuit faults, this document does not apply. Further vehicle diagnosis is
required.
Fault-trace wire for affected component and ensure that there is no chafing or damaged areas. Ensure that all
connections are secure and wires are firmly attached to connectors. If the inspection does not find a root cause, disconnect and reconnect the connectors to the SRS Control Unit.
If the fault occurs again, or if this is a reoccurrence of the same problem, replace the SRS control unit. Ensure the
new control unit is Q4 level or higher.
NOTE: SRS control unit A177 900 0404 28 is available in very limited quantities, and may only be replaced if the fault
returns again after first disconnecting and reconnecting of the connector to the SRS control unit. Only VOR orders will
be allowed, so a unique VIN will be required for each order and demand will be closely monitored. MBUSA is counting
on your collaboration to ensure parts availability of A177 900 0404 28 for customer complaints.
Attachments
File
Description
Q4 SRS Example.jpg
Location of Q Level on SRS Control Unit
Symptoms
Body / Safety system / Airbag/Supplemental restraint system SRS / Indicator lamp / SRS indicator lamp / lit
Body / Safety system / Seat belt / Seat belt indicator lamp / lit
Body / Safety system / Airbag/Supplemental restraint system SRS / Indicator lamp / Airbag / lit
06-05-2020 7:06 PM
© Copyright Mercedes-Benz
AG
MYNELSO
Page 1/5
Control unit/fault code
Control unit
Fault code
Fault text
N2/10 - Supplemental restraint B000313
system (SRS) (ORC177) (A
(177),CLA (118))
The squib for the vent valve 'Driver airbag' has a malfunction.
There is an open circuit.
N2/10 - Supplemental restraint B003813
system (SRS) (ORC177) (A
(177),CLA (118))
The squib for the right rear sidebag has a malfunction. There is
an open circuit.
N2/10 - Supplemental restraint B001013
system (SRS) (ORC177) (A
(177),CLA (118))
The squib for the front passenger airbag (stage 1) has a malfunction. There is an open circuit.
N2/10 - Supplemental restraint B1B3613
system (SRS) (ORC177) (A
(177),CLA (118))
The squib for the emergency tensioning retractor at the center of
the first seat row has a malfunction. There is an open circuit.
N2/10 - Supplemental restraint B275013
system (SRS) (ORC177) (A
(177),CLA (118))
The squib for the sidebag 'Driver' has a malfunction. There is an
open circuit.
N2/10 - Supplemental restraint B284F13
system (SRS) (ORC177) (A
(177),CLA (118))
The squib for pyrofuse 'High-voltage on-board electrical system'
has a malfunction. There is an open circuit. (OCM177)
N2/10 - Supplemental restraint B001213
system (SRS) (ORC177) (A
(177),CLA (118))
The squib for the vent valve 'Front passenger airbag' has a malfunction. There is an open circuit.
N2/10 - Supplemental restraint B001113
system (SRS) (ORC177) (A
(177),CLA (118))
The squib for the front passenger airbag (stage 2) has a malfunction. There is an open circuit.
N2/10 - Supplemental restraint B275113
system (SRS) (ORC177) (A
(177),CLA (118))
The squib for the sidebag 'Front passenger' has a malfunction.
There is an open circuit.
N2/10 - Supplemental restraint B000113
system (SRS) (ORC177) (A
(177),CLA (118))
The squib for the driver airbag (stage 1) has a malfunction. There
is an open circuit. (OCM177)
N2/10 - Supplemental restraint B00E313
system (SRS) (ORC177) (A
(177),CLA (118))
The squib for the left rear emergency tensioning retractor has a
malfunction. There is an open circuit.
N2/10 - Supplemental restraint B008013
system (SRS) (ORC177) (A
(177),CLA (118))
The squib for belt force limiter 'Driver' has a malfunction. There is
an open circuit.
N2/10 - Supplemental restraint B007913
system (SRS) (ORC177) (A
(177),CLA (118))
The squib for the emergency tensioning retractor 'Belt end fitting' (driver) has a malfunction. There is an open circuit.
N2/10 - Supplemental restraint B00E613
system (SRS) (ORC177) (A
(177),CLA (118))
The squib for the emergency tensioning retractor at the right of
the third seat row has a malfunction. There is an open circuit.
N2/10 - Supplemental restraint B001313
system (SRS) (ORC177) (A
(177),CLA (118))
The squib for the front passenger kneebag has a malfunction.
There is an open circuit.
06-05-2020 7:06 PM
© Copyright Mercedes-Benz AG
MYNELSO
Page 2/5
N2/10 - Supplemental restraint B00E413
system (SRS) (ORC177) (A
(177),CLA (118))
The squib for the right rear emergency tensioning retractor has a
malfunction. There is an open circuit.
N2/10 - Supplemental restraint B002113
system (SRS) (ORC177) (A
(177),CLA (118))
The squib for the left windowbag/headbag has a malfunction.
There is an open circuit.
N2/10 - Supplemental restraint B007A13
system (SRS) (ORC177) (A
(177),CLA (118))
The squib for the emergency tensioning retractor 'Belt end fitting' (front passenger) has a malfunction. There is an open circuit.
N2/10 - Supplemental restraint B00E713
system (SRS) (ORC177) (A
(177),CLA (118))
The squib for the emergency tensioning retractor at the left of the
third seat row has a malfunction. There is an open circuit.
N2/10 - Supplemental restraint B273513
system (SRS) (ORC177) (A
(177),CLA (118))
The squib for pyrofuse 'On-board electrical network line' has a
malfunction. There is an open circuit.
N2/10 - Supplemental restraint B002213
system (SRS) (ORC177) (A
(177),CLA (118))
The squib for the left rear window airbag/head airbag has a malfunction. There is an open circuit.
N2/10 - Supplemental restraint B000113
system (SRS) (ORC177) (A
(177),CLA (118))
The squib for the driver airbag (stage 1) has a malfunction. There
is an open circuit.
N2/10 - Supplemental restraint B002A13
system (SRS) (ORC177) (A
(177),CLA (118))
The squib for the right rear window airbag/head airbag has a malfunction. There is an open circuit.
N2/10 - Supplemental restraint B007E13
system (SRS) (ORC177) (A
(177),CLA (118))
The squib for emergency tensioning retractor 'Driver' has a malfunction. There is an open circuit.
N2/10 - Supplemental restraint B002913
system (SRS) (ORC177) (A
(177),CLA (118))
The squib for the right windowbag/headbag has a malfunction.
There is an open circuit.
N2/10 - Supplemental restraint B1C1E13
system (SRS) (ORC177) (A
(177),CLA (118))
The "Driver" seat occupancy recognition has a malfunction. There
is an open circuit.
N2/10 - Supplemental restraint B000213
system (SRS) (ORC177) (A
(177),CLA (118))
The squib for the driver airbag (stage 2) has a malfunction. There
is an open circuit.
N2/10 - Supplemental restraint B007F13
system (SRS) (ORC177) (A
(177),CLA (118))
The squib for emergency tensioning retractor 'Front passenger'
has a malfunction. There is an open circuit.
N2/10 - Supplemental restraint B003013
system (SRS) (ORC177) (A
(177),CLA (118))
The squib for the left rear sidebag has a malfunction. There is an
open circuit.
N2/10 - Supplemental restraint B000413
system (SRS) (ORC177) (A
(177),CLA (118))
The squib for the driver kneebag has a malfunction. There is an
open circuit.
N2/10 - Supplemental restraint B008213
system (SRS) (ORC177) (A
(177),CLA (118))
The squib for belt force limiter 'Front passenger' has a malfunction. There is an open circuit.
06-05-2020 7:06 PM
© Copyright Mercedes-Benz AG
MYNELSO
Page 3/5
Parts
Part number
ES1 ES2 Designation
A17790004042 8
Quantity Note
CONTROL UNIT, COMPLETE 1
EPC
Not every repair requires replacement. Follow attached work instructions.
Operation numbers/damage codes
Op. no.
Operation text
Time
Damage
code
Note
82485 73
Repair type 7 for exercising connector
82485 73
Repair type 1 for replacing SRS CU
Attachments
06-05-2020 7:06 PM
© Copyright Mercedes-Benz AG
MYNELSO
Page 4/5
Q4 SRS Example.jpg:
06-05-2020 7:06 PM
© Copyright Mercedes-Benz AG
MYNELSO
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TSB/Document ID: LI54.21-P-070658
Replacement Service Bulletin Number:
MFR Communication Date: 2020-06-05
MFR Internal Campaign ID/Software Version:
Communication Type: Service Bulletin/Repair Instructions
NHTSA Components: AIR BAGS
MFR Component System:
MFR Component Subsystem:
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