SRS light on, fixed.

[Gabs]

Hi all,
Last summer when I haf the ETA replaced in my car I asked my mechanic to sort a very anoying grinding noise that steering wheel produced when it was moved from side to side. He sorted it out by lubricating the contact rings and the brushes located behind the steering wheel. However from that time the SRS light came on intermitently.
I read on the MB workshop manual that it is not recommended to lubricate those parts, so today after lunch I decided to fix it. When I removed the steering wheel I noticed that the copper brushes had some burrs on the edges and that the brass contact rings displayed a reddish layer, quite likely to be caused by the continous friction between the rings and the brushes.
First of all I removed all the lubricant from the contact rings and the brushes. Then I chamfered the upper edges of the brushes with a small file making sure that all the burrs were removed. After, I polished the contact rings with green scotch brite. To finish with it, I sprayed some silicon oil on the contact rings and brushes and wiped them with a clean rag to make sure that all the bits and bobs were clean.
Once I reinstalled the stering wheel together with the airbag, I connected the baterry ground, turned the engine on, moved the steering wheel from side to side and the the SRS light remained off and no grinding noise came from it either.
I am a happier man now!

Gabriel

 

[Christian_K]

Wow thanks very much for that tip, will be quite helpful for somebody for sure.

 

[gerryvz]

I believe you should use special "dilectric grease" for these contact ring connections which should lubricate but not affect the SRS light. I actually need to do this both on my E500 and my 560SL. Applying a light coat should do the trick and provide adequate lubrication without causing electrical glitches/issues.

Cheers,
Gerry

 

[Gabs]

Yeap, I agree with you Gerry.
In theory, that silicon oil is ment to work on electric devices and also on plastic, rubber and many other syntetic surfaces. I used it to lubricate the door seals on my 500E and did the job quite well.