LI54.21-P-070658 Service Bulletin/Repair Instructions

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
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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.
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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
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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
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Q4 SRS Example.jpg:
06-05-2020 7:06 PM

© Copyright Mercedes-Benz AG
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