Notes on the use of paint scraping nuts on ground connections - AH00.19-P-1000-20A

MODEL 117, 156, 166, 172, 176, 190, 205, 217, 222, 242, 246, 292 

Fig 1: Identifying Cable Lug And Paint Scraping Nut

Courtesy of MERCEDES-BENZ USA

As of MODEL 172 the concept for contacting electrical ground connections to the vehicle body has been altered. All body ground connections are covered-up in the production process with a coat of paint.

Important:  To ensure that an electrically conductive connection process can be made through a painted ground connection to the body, it is absolutely essential that only the new developed paint-scraping nut (2) is used for the ground connections. The paint-scraping nut (2) technique ensures that paint is removed during the screwing-on process and therefore an electrical connection set up between the external thread of the ground connection and the inside thread of the nut.

The use of other nuts that deviate from the specified paint-scraping nut (2) (e.g. for retrofits, repairs), may result in a problem.

The following should still be observed: 

1. Assignment of new ground connections:

   If, for retrofits, a ground connection that was not previously used is assigned, make sure that the contact surface of the cable lug (1) is flat (no welding splatter or suchlike), to ensure that the threaded connection does not result in tension or deformation to the cable lug (1).

2. Repeated use of paint-scraping nut (2):

   Before screwing on the paint-scraping nut (2) to the ground connection again, paint abrasion in the grooves of the paint-scraping nut (2) must be removed (e.g. using compressed air).

3. Paintwork rectification in ground connection area:

   To avoid any excessively thick paint coats, paintwork protection must be applied to the connection prior to any paintwork rectification in the ground connection area (e.g. screwed-on nut or cap).