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1992 mercedes benz 300sl r129 722.5 auto trans not shifting into 5th gear (od)
1992 Mercedes-Benz 300SL

1992 Mercedes Benz 300SL R129 722.5 auto trans not shifting into 5th gear (OD)

(1992 Mercedes-Benz 300SL)
This is a 5 speed automatic transmission,first 4 gears mechanical with the 5th (OD) gear electronically engaged.Fluid is up and looks great.Tested for codes and have none.Tested micro switch in shift lever (a well known problem),tested good.Checked and cleaned all fuses and cleaned their fuse box contacts.Climbed underneath and did not find any hanging wires.
What seems to make the problem better or worse? Nothing makes a difference
How long have you had this problem? Since I bought the car 4 months ago.
Tags: nothing else to add, mercedes benz, 300sl
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1 answer & 3 comments
Popular Answer
on November 11, 2017
Hello,
With all of that tested, make sure to test the solenoid. If memory serves me right, this can be done at the transmission without removing the pan.

You will want to look up the proper procedure, and I recommend the Bentley service manual, or using alldatadiy.com
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on November 11, 2017
Thanks Casey40510,I'll research and give that a look.Also,I just read that there is a electrical plug that eventually leaks and get trans fluid in it which causes problems.I don't recall seeing that plug so another crawl under is in the near future.Thanks for the advise and if you think of anything else I'm listening.Thanks!
on November 11, 2017
No problem,
I forgot all about that. Yes, that is a likely cause. There should only be two or three electrical connections on that entire transmission, so I would check them all to be safe.

on April 05, 2018
April 2018.Taking the cover off after the nasty winter here in Massachusetts.Still hoping I dont have to do a major job on this tranny to get it to shift into 5th gear.I'm surprised that I have not heard back from more people having this problem.I know its common.I've talked to a few MB repair places and they each have there own ideas but they tell me it could cost up to $500. just to diagnose the problem.I usually do my own work and its really tough to pay that kind of money if I can do it (and have the tools) myself.Anybody that even has the slightest theory is welcome to join in.It may very well help many more than just me.Thanks!
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on November 11, 2017
Hello,
With all of that tested, make sure to test the solenoid. If memory serves me right, this can be done at the transmission without removing the pan.

You will want to look up the proper procedure, and I recommend the Bentley service manual, or using alldatadiy.com
Sign in to reply
on November 11, 2017
Thanks Casey40510,I'll research and give that a look.Also,I just read that there is a electrical plug that eventually leaks and get trans fluid in it which causes problems.I don't recall seeing that plug so another crawl under is in the near future.Thanks for the advise and if you think of anything else I'm listening.Thanks!
on November 11, 2017
No problem,
I forgot all about that. Yes, that is a likely cause. There should only be two or three electrical connections on that entire transmission, so I would check them all to be safe.

on April 05, 2018
April 2018.Taking the cover off after the nasty winter here in Massachusetts.Still hoping I dont have to do a major job on this tranny to get it to shift into 5th gear.I'm surprised that I have not heard back from more people having this problem.I know its common.I've talked to a few MB repair places and they each have there own ideas but they tell me it could cost up to $500. just to diagnose the problem.I usually do my own work and its really tough to pay that kind of money if I can do it (and have the tools) myself.Anybody that even has the slightest theory is welcome to join in.It may very well help many more than just me.Thanks!

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