I believe that 1992 was the first year for the W140 and they all have the Closing Aid. All the S class w140 and newer use closing Aid. I did another post just for this Closing Aid fix. I do not see it any more. Maybe it was moved . At any rate. This fix that I have for closing AID is a big break through for those annoying closing aid gremlins. My Father got rid of his S500 because of it. He wound up paying over 3000 dollars for pump and lines and door calibrations and on and on. Mercedes even flew some Engineers out from NYC to look at the car. After all that, He still had intermittent problems with his closing AID. He got so fed up he sold the car he loved or hated. He hated it.. He love it !! He hated it !! . He still loves that car and now that I have the fix, he is looking to buy another. It may sound strange to sell a car just because you have to slam the doors shut or reset the circuit when it happens.. But.. After almost 2 years of dealing with it after spending so much money to have it fixed.. Well.. He did... He got a letter from Mercedes saying it was fixed and with that letter he traded in the car for a Hemi that did not have closing AID doors. And now that I have a 400SEL and I let him drive it.. And the Doors work perfectly with my circuit. My Dad now wants to trade his 300c for my 400sel.. I may do it.. As long as he promised to trade back.. And.. I know he does not want to give the car back.. so.. Now he is looking for his own when he gets back home from Texas... He likes his Little Lexus LS430 and the 300C is fast.. But.. There is nothing like the Big S Class by Mercedes. And he wants one again now that there is a fix for the doors.. Yes !!!