I am starting out on a 1600 mile trip to get back home with my 92 s600. My tranny seemed to be working alright, and then when i got on the highway it wouldnt shift past 3rd!! When i got to the next city, it wouldnt shift past 2nd. I am at a loss and need some urgent help. I've read a few threads quickly... it seems i should change the tranny fluid/ also drain the torque converter for starters. Should i be reseting the tranny somehow? Ie is it a control module problem?? I had it tested and they said the current fluid was at the right amount, and tested well on vacuum. Any advice is greatly appreciated, this is a major problem for me at the moment since i need to get back. I hope it can be remedied without a rebuild!
Your car starts from 2nd, so you should feel 2 shifts: 2 - 3 and 3 - 4.
There is nothing to reset, no control module, only hydraulics and vacuum. The only electric control is kick-down switch and solenoid. Check the button under the gas pedal if it clicks on and off freely. You could get under the car and disconnect kick down solenoid if it was a problem.
Mike
thanks for the info! i think you may be right it looks like the module is cracked. are you saying to take it off and see how it runs with it off to verify? i think i will replace it.
If the tranny has not had regular (30k miles) fluid/filter change, you could just have a bunch of gunk plugging the filter or some of the smaller passages. I had the syptoms you speak of on another Benz I owned. It took 2 fluid/filter changes a month apart to finally get it shifting right. The car had 145k miles on it when it happened and is still rolling without problem now at 260k miles.
Of course it could be something else, but this is a relatively cheap way to start the dianosis. Also, if you take the filter out, compare the color of the filter media to the new one. The media on my benz was quite brown and the fluid was brownish-red.
im not sure if 92 had some kind of electronic shifting controls. i know mine does its a 96 s500. what happened to mine was the tranny realized it wasnt working so it went into limp mode, and no mil lights went on.... nothing!!!
after replacing the tranny same thing my car was also stuck in second.... i took it to ammco transmissions and they pulled up the codes from the transmission and deleted them!
i guess these cars cam with two seperate diagnostic systems one for engine and one for tranny?? or some kind of bullshit like that! try taking it to ammco transmissions they do their diagnostics for free and to delete it is going to cost you but might as well try it out!
if there are codes from the transmissions then you need a new transmission in most cases. but deffenitly try changing oil and filter first!
One bit of caution I've been given by transmission mechanics:
It's alright to change the fluid and the filter, but flushes can damage an older transmission by removing gunk that might be keeping it running via plugging holes, etc. I thought a flush might be nice to clean out everything, but I guess it's not always the best idea.
Also, most of the time all a transmission shop will do is change the fluid in the pan and the filter. So this is a job that if you don't mind laying on your back for a while, it's pretty easy (though a friend helps to get the pan back up ).
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thanks for the advice guys. I am going to change the fluid and filter.. i just got the car and dont know the last time it was done. It appears that it wasnt the kickdown switch, and definately seems hydraulic or vacuum related.. maybe it needs a valve body rebuild?? Unfortunately i'm not well versed in transmissions.
BTW, don't be afraid to do this twice in a short amount of time. And, make sure you drain the torque converter too or you will only be replacing a small amount of fluid. The key indicator is the color of the existing fluid and filter. When I changed mine the second time (because the symptoms reappeared) the filter I had just replaced a month before was somewhat brown as well. Likely from the gunk flushed out of the passages. I changed it again a year later and all was well.
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