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Discussion Starter · #1 ·
I have a 93 4.6 and 4r60w in 46 merc. On a recent trip we hit a bump and over drive shifted to 3rd. Button would not work. Short time later o/d came back but went out on another bump. Checked wiring then pulled pan and put a shift and tcc selinoid in no bad stuff in the pan and check o/d servo no problem there. Going up the walls looking for answers. Help.
 

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1997 Thunderbird LX
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Could be a bad MLPS, the shift sensor on the side of the tranny. If it's the original, chances are it could be bad.

Joe
 

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Discussion Starter · #3 ·
Been checking that, but does it affect o/d?
I have 2 and checked ohms on both but can only get readings on 1st and 2nd.
 

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1997 Thunderbird 4.6, 1998 Mark VIII LSC
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Do you have tools to read live data from the PCM? If so watch the commanded_gear PID to see if it's shifting to 3rd because it's being commanded to (MLPS issue) or because of an electrical or mechanical fault.
 

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Discussion Starter · #5 ·
Going to tyranny shop tomorrow and see if they can do that. Will also look at a new mlps.

I've looked at all the treads on overdrive and nothing comes close to this problem. Will post what I find.
 

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1997 Thunderbird LX
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Glad you got it figured out, sweet looking ride! (y)

Is that your little guy?

Joe
 
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Discussion Starter · #10 ·
Back again, took a 100 mile one way trip to car show on a new mlps. On the way back lost od and when we got to town low gear was also gone. Been working with 3 mlps over the last few days and had overdrive for a few miles but it's gon again. This is driving me nuts. I'm thinking of pulling the pan again and looking at the shift selinoids, but checked out when I installed them 2 weeks ago. Any clues you might have. Appreciate it.
 

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Discussion Starter · #11 ·
Did a 6hundred mile trip this week end and problems again. everything was great the week before i left o/d working and ist gear. about 175 miles the o/d left and would flare out once in a while. made to Boise on 3rd gear did not have access to testing equipment so thought the mlps was out again, it was a used one. installed a new one from Orielly's, test dive still not working. so drove home 350 miles in 3rd never saw o/d. pulled the pcm out of it's hole and let it sit on floor and when i would move it around it would flare out the trans. so looks like some electrical issue. any one know which pins might be involved in making the trans lose gear. then i will check that and i also have a j-mode valve body I may reinstall. the fun starts tomorrow.
 

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That is the teflon seals on the shaft that feed the direct clutch The one piece seals fix that.
Unfortunately, the whole tranny needs rebuilt.
 

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Discussion Starter · #13 ·
Glory bee! I had the pcm standing on end laying against the trans tunnel. Per chance I laid it on its side and volla I have on and 1st gear back. So there is 18 inches of wiring I need to check out for some kind of short or broken wire. Surmising it has to be on a shift seliniod circuit. At least that may be the starting point. Any ideas and thanks to all for the input.
 
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