My 88 300E would make the light come on sometimes when I was driving down the road.. Seems the part of the contact ring that got the most wear was right there in the middle.. IE with the steering wheel centered. The light would only come on sometimes. Replacing the contact ring fixed it.. I would think that if the light were on all the time that it might not be the contact ring.. Even on mine if I turned the wheel off center the light would go out. Hope this helps.

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Bill

Backyard Shadetree Mechanic, 30 years running.

1987 300TD
1988 300E (sold, sniff)
1999 S320
1981 Volkswagen Rabbit Truck (Diesel)
2001 Ford Expedition
1988 Suzuki Samurai
On my list to buy: R129, for me, and a R107 for my wife.