Clean SRS Control Unit Contacts – 2019-2021 Mercedes-Benz CLA-Class, A-Class, GLA-Class & GLB-Class

TO: Mercedes-Benz Dealer Principals, General Managers, Sales Managers, Service Managers, Parts Managers	FROM:  Gregory Gunther, Department Manager, Vehicle Compliance and Analysis, Engineering Services
RE: Service Campaign 2020080013 Launch Notification Clean SRS Control Unit Contacts MY19-21 118, 177, 247 (CLA-Class, A-Class, GLA-Class  GLB-Class)	Date: September 4, 2020

 

IMPORTANT NEW SERVICE CAMPAIGN LAUNCH INFORMATION

IN-VEHICLE NOTIFICATION

To enhance the Mercedes-Benz customer experience, an in-vehicle notification will be sent to the affected vehicles for this service campaign. The notification will be sent to approximately 6,000 VINs per week. An example of the message that will appear in a flagged vehicle is shown below.

 

This message will appear at engine start beginning September 7, 2020 and will continue every 30 days until the service campaign has been completed. Dealers are reminded to submit warranty claims in a timely manner to reduce the possibility of redundant messages.

 

 

Please note that all customer inquiries should be directed to the Customer Assistance Center at 1-800-FOR-MERCEDES.

 

Sincerely,

 

Gregory Gunther

 

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Campaign No. :	Campaign Desc. :		Clean SRS Control Unit Contacts
2020080013	20P9192108
This is to notify you of a Service Campaign launch concerning cleaning of contacts on the SRS control unit on 38,627 Model Year (“MY”) 20192021 CLA-Class, A-Class, GLA-Class, and GLB-Class vehicles. Affected VINs will be flagged in VMI as “OPEN” on September 4, 2020.
Background
Issue		Mercedes-Benz AG (“MBAG”), the manufacturer of Mercedes-Benz, has determined that on certain MY19-21 CLA-Class, A-Class, GLA-Class and GLB-Class (118, 177, and 247 platform) vehicles, an increased electrical resistance may occur between the connector block of the electronic control unit and the connector pins for the Supplemental Restraint System (SRS) wiring harness. The SRS control unit might detect the increased resistance in various SRS circuits (e.g. driver/ front passenger airbag, seat belt tensioner) which could lead to illumination of a warning message (yellow) and a warning lamp (red) in the instrument cluster. The functionalities of the SRS system are not impaired.
What We’re Doing		MBUSA will conduct a Service Campaign. An authorized Mercedes-Benz dealer will inspect and clean the SRS control unit connector contacts.  Customers included in this Service Campaign will be notified through in-vehicle notification in waves of approx. 6000 per week with subsequent notices sent every 30 days.
Parts		Special tools required. A test tool must be prepared before the work procedure is performed. The test tool is reusable, but the cleaning pads must be replaced per the Work Instructions.
Vehicle Model Year(s)		2019-2021
Vehicle Model		CLA-Class, A-Class, GLB-Class
Vehicle Populations
Total Campaign Population		38,627
Next Steps/Notes
AOMS/SOMS		AOMs – This Service Campaign may generate questions from your dealers.
While we regret any inconvenience this may cause, MBUSA is determined to maintain a high level of vehicle quality and customer satisfaction. Please refer all customer inquiries to the Customer Assistance Center at 1-800-FOR-MERCEDES.

 

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Campaign No. 2020080013, September 2020

 

TO:	ALL MERCEDES-BENZ CENTERS
SUBJECT:	Model CLA-Class, A-Class, GLA-Class and GLB-Class (118, 177, and 247 platform) Model Year 2019-2021 Clean SRS Control Unit Contacts

 

 

Mercedes-Benz AG (“MBAG”), the manufacturer of Mercedes-Benz, has determined that on certain MY19-21 CLA-Class, A-Class, GLA-Class and GLB-Class (118, 177, and 247 platform) vehicles, an increased electrical resistance may occur between the connector block of the electronic control unit and the connector pins for the Supplemental Restraint System (SRS) wiring harness. The SRS control unit might detect the increased resistance in various SRS circuits (e.g. driver/ front passenger airbag, seat belt tensioner) which could lead to illumination of a warning message (yellow) and a warning lamp (red) in the instrument cluster. The functionalities of the SRS system are not impaired. MBUSA will conduct a Service Campaign. An authorized Mercedes-Benz dealer will inspect and clean the SRS control unit connector contacts. Customers included in this Service Campaign will be notified through in-vehicle notification in waves of approx. 6000 per week with subsequent notices sent every 30 days.

 

Prior to performing this Campaign:

• VMI must always be checked before performing campaigns to verify that the campaign is required on a specific vehicle. Always check for any other open campaigns, and perform accordingly.
• Please review the entire Campaign bulletin and follow the repair procedure exactly as described.

 

Approximately 38,627 vehicle is affected.

 

Order No. P-SC-2020080013

 

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 Test tool must be prepared before the work procedure.

See description “Preparation of test tool” on page 9 and 10.

 

Before beginning work, no SRS fault message may be present in the instrument cluster!

If a SRS fault message is present before the start of work, it must be rectified.

The fault rectification may not be invoiced together with the campaign.

 

 

Work procedure 

1. Disconnect ground line of on-board electrical system battery.

For basic data, see10-P-0003MFA.

2. Fold away left and right floor covering in area of center console and place powertrain control unit (A, figure 1) with connected lines to one side.

For basic data on control unit removal, see AR91.60-P-0615MFA.

Contrary to the work instructions in WIS, the center console does not have to be disassembled.

Figure 1

 

3. Disconnect the contacts of both electrical connectors (20- and 104-pin) of the Supplemental Restraint System control unit (SRS) (figures 2 – 4).

To release the 20-pin plug, push the red locking clip (B, figure 2) in the direction of the arrow.

To disconnect the 20-pin plug (C, figure 3), press the lock downwards (in direction of the arrow) by using an allen wrench.

Figure 2 Figure 3

 

4. Release three nuts (D, figure 4) for the Supplemental Restraint System control unit (SRS) and remove this.

Figure 4

 

5. Place Supplemental Restraint System control unit (SRS) on the ESD mat for processing at the workplace.

The contacts of the Supplemental Restraint System control unit (SRS) may not be touched.

 

6. Clean all electrical connection pins in the control unit with extreme caution by means of cleaning brushes (C, figures 5 and 6).

6 cleaning brushes (figures 7). For the complete cleaning procedure a total of six cleaning brushes must be

Figure 5

 

Figure 6

 

Figure 7                                                                                      

 

Observe the information on preventing damage to the electronic components due to electrostatic discharge AH54.00-P-0001-01A.

Ensure extreme cleanliness.

Slide cleaning brushes in insertion direction onto the connection pins up to end stop and remove again (figures 5 and 6).

The cleaning brushes must be placed parallel to the lower edge of the control unit (Figures 5, 6 and 8).

An insertion of the cleaning bushes 90° offset to the lower edge of the control unit can result in damage to the connection pins (figures 9 and 10).

All movements at the connectors must be executed in a linear manner in order to not damage (bend) the pins.

Do not twist. A twisting of the cleaning brush can damage or bend the adjacent contacts.

Up to two connection pins can be cleaned simultaneously.

All connection pins must be cleaned. No connection pins may be omitted.   Observe the cleaning sequence in operation step 7.

 

7. Perform cleaning in the following sequence:

The SRS control unit has 4 connection rows (1-4 figure 9).

A total of 6 cleaning brushes are required for the complete cleaning process.

• Connection rows 1 and 2 must be fully cleaned with a cleaning brush.

Repeat this process two more times with a new cleaning brush for each time.

• Connection rows 3 and 4 must be fully cleaned with a cleaning brush.

Repeat this process two more times with a new cleaning brush for each time.

Each contact is thus cleaned three times.

No cleaning agents or similar may be used with the cleaning brush.

Figure 8

 

Figure 9 – correct

 

Figure 10 – Incorrect

 

Check for damage after cleaning:

8. Slide on the test coupling (104-pin and 20-pin) from above onto the cleaned SRS control unit without any force up to the end stop and remove the test coupling (figure 11 and 12).

The objective is to detect with this empty coupling housing whether the pins are OK and not bent after the cleaning.

If both test couplings can be inserted without any force up to the end stop (see F and G figures 11 and 12), the pins are OK.

In the case of damaged control unit pins, the SRS control unit is unusable and must be replaced (dispose of the control unit properly).

The contact carriers must be fully inserted in the support body of the coupling housing and align with the control unit edge (F, figure 11).

The support body of the 20-pin male test connector must align with the control unit edge (G, figure 12).

The test tools can be reused (see annex “Preparation of test tool” on page 9.

Figure 11

 

Figure 12

 

9. Visual inspection of the pins in the control unit (figure 13).

No control unit pins may be bent.

In the case of damaged control unit pins, the SRS control unit is unusable and must be replaced.

For basic data, see AR91.60-P-0615MFA.

Figure 13

 

 

10. Make the used cleaning bushes unusable at the end of the cleaning work (figure 14).

Cleaning brushes may not be reused. 

Figure 14

 

11. Assemble in reverse order.

First tighten the SRS control unit with the correct torque (10) and then connect.

For basic data, see AR91.60-P-0615MFA.

 

12. Switch ignition to position 1. To do so, press start button once without touching the brake pedal. Check whether airbag indicator lamp (H, figure 15) permanently goes off after a few seconds.

The SRS check is thus completely ensured.

Figure 15

 

Preparation of test tool

The test tools (104-pin and 20-pin) must only be produced once per workshop and reused. The test tools must be stored in a clean, dry, and secure location.

A visual inspection must be carried out before every use. As soon as contamination or damage is noticeable, this test tool must be replaced by a new one. Dispose of the old test tool.

 

1. Remove retaining bracket (figure 16) from coupling housing (A 029 545 90 26) and dispose of it.

Figure 16

 

2. Insert both contact carriers with low effort into the coupling housing up to the end stop (figure 17).

Figure 17

 

3. Assemble airbag control unit coupling housing (A 166 545 04 26) and contact carrier (A 005 545 23 40) (figure 18 and 19).

Insert contact carrier (yellow) of 20-pin plug with low effort in coupling housing (black) up to

Figure 18

 

Figure 19

 

4. Carefully remove locking clip (red) and engagement lever (black) from the plug housing and subsequently dispose of (figure 20).

Figure 20

 

 

Special Tools

Qty.	Part Name	Part Number
1	ESD kit	W 000 589 52 98 00

 

Parts

Qty.	Part Name	Part Number
6	Cleaning bush	A 000 540 38 04

 

Test Tool Parts Information

Qty.	Part Name	Part Number
1*	Coupling housing	A 029 545 90 26
1*	Contact carrier	A 005 545 53 40
1*	Contact carrier	A 005 545 54 40
1*	Airbag control unit coupling housing	A 166 545 04 26
1*	Contact carrier	A 005 545 23 40

 

* Test tool may only be ordered and claimed once per workshop and be reused for subsequent repairs.

 

Warranty Information

Operation: Clean pins at control unit (SRS)(02-1056)

 Includes: Disconnect and reconnect the battery.

Damage Code	Operation Number	Labor Time (hrs.)
91 921 08 7	02-1056	0.6

 

Note

Operation Number labor times are subject to change.

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Clean SRS Control Unit Contacts
Model CLA-Class, A-Class, GLA-Class and GLB-Class (118, 177, and 247 platform)
Model Year 2019-2021

P-RC-2020080013

 

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Last update on 2025-05-08 / Affiliate links / Images from Amazon Product Advertising API

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