98 SL500 will not shift intermittently - PeachParts Mercedes-Benz Forum

Markymark · #1 07-01-2008, 04:50 PM

I have a 98 SL500 and I have been having problems with the transmission not shiffting sometimes. It will just stay in 1st or 2nd gear for a few minutes then shift normal. Also when I'm driving at cruising speeds the trans will downshift to 2nd gear on its own. If I put it in nuetral and back into drive several times it will eventually shift normal. But usualy it will just upshift then downshift several time then clear up and act normal for 3 months or so. I went to dealer and they never heard of it so I'm hoping someone here as heard of this problem and can maybe help me. I already changed fluid and filter and the oring for harness going into the side if trans. I also checked for codes and found none. Any help will be greatly appreciated.

TMAllison · #2 07-01-2008, 05:01 PM

Do you have SDS or compatible scanner? Thats the only way you are going to see those codes.

The dealer should have looked at adaptation values and told you what was worng.

JFawcett · #3 07-03-2008, 10:42 AM

Are you getting any dash lights or any other strange behavior? Mine S500 was doing that but it was accompanied by no power steering, no power brakes and about 1/2 the warning lights on dash coming on - then poof, all better. It was the Z-soldering in the wiring harness outside the fuse box and computer box. Takes time to find, but if no codes - may want to start looking there.

Markymark · #4 07-04-2008, 01:36 AM

I'm not sure what scanner was used but they came up with nothing. I dont have any other problems that occur or lights that come on when it acts up. Maybe I should try an other dealer.

eddie a · #5 07-04-2008, 07:22 AM

You have to be patient... The car will get fixed but,, DONT GO TO A DEALER.. The people on this web page will help.. They have bailed me out a few times.. I just was a mess untill the car was fixed probably like you.. Just be as detailed in your discription of the problems as you can.. and it might take a day or so to get the right response.. Good luck! unfortunatly Im not the guy to help you.. But there are some smart guys here ..

TMAllison · #6 07-04-2008, 12:02 PM

You should determine what scanner the shop has. OBDII wont read trans codes; only SDS or similar very high end scanners will.

You might check the electrical harness entering the trans and see if any fluid is wicking up the wires past the seal. If so, follow the harness up to the computer and look there too. Fairly common problem on ealrier 722.6 trans. New valve body and sometimes ECU fixes that usually. I'd get a second opinion before replacing of course.

SDS shoud provide a wealth of data and adaptation values showing what your trans has been up too recently......there are times where the dealer is the best place to be.