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Discussion Starter · #1 · (Edited)
Hi, I have a 1989 2.3L Mustang and when it shifts into OD, it feels like I lose power or like its trying to shift into OD but can't. I've had some transmission issues in the past (mainly leaks) but this is new. It started happening one night after I ran out of ATF and it stopped moving (duh). I then refilled it (Actually I think I overfilled it by 1/4 - 1/2 a qt) and started driving it home when I noticed it. Every other gears seem to shift like before except when I hit OD. I pulled the trouble codes and I didn't get anything, it said that it passes. Any idea what could cause this?

EDIT: Also it runs and shifts perfectly fine in the Drive position (not the OD position) Is there any problem in driving it like that until i fix the OD issue, as this is my only real working car at the moment?
 

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you wont have any issue driving around in Drive, i have done it myself in past winters (helped keep my stang under control in snow/ice conditions). just take it easy on the highway driving and hard accelerations since you are locking out overdrive function and therefore making the engine work harder.

a little bit of info in case you didnt know, but the a4ld trans is a c series trans (as was used on earlier stangs) with a planetary overdrive unit added on. it allows for overdrive function obviously ;) the shifting in the trans needs vacuum to properly shift, ie the vacuum modulator and egr working properly, as well as properly adjusted bands and shift solenoids (sorta, its complicated and most likel;y not related to your problem). however since you said the car shifts fine in regular drive i doubt your problem is in this area. it is most likely in the planetary unit itself due to how you describe your issue. unfortunately my experience is with the parts of the trans that are not the planetary, so i cant be of much more help than this sorry.gif. but dont worry, we have several other members who do have good experience with the planetary unit who should pop in and help you out. absolute worst case scenario you can buy a new planetary unit for your trans to restore the overdrive if your current unit turns out to be toast.
 

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One of the most common issues I encountered as a Ford Mechanic, were 3-4 shift issues with A4LD equipped vehicles. These can be caused by a variety of items, but the most common failure is usually the 3-4 shift solenoid followed by low fluid pressure issues. If you have a shop fix this for you, the're going to want a lot of money.

The fact that it's "trying" to shift into 4th, makes me think that the computer and wiring are not going to give you a clear picture when you do voltage and continuity checks. I would point you towards changing the 3-4 solenoid. You have to drop the pan to do this and pull the valve body out, which is not that hard to do, but can be a little messy unless you have a sizable pan underneath the transmission. If you're changing the 3-4 solenoid, may as well change the filter and the converter solenoid too. In a shop environment, this takes me a little over an hour to do.
I would suggest a factory repair manual if you are going to do the job
 

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Discussion Starter · #4 ·
Okay Thanks guys! So I'm planning on dropping the pan and valve body, etc so I can check to see whats going on down there this weekend. See if its the servo or band or whatnot. How can I test to see if the servo is working or defective? Also where is a good place to find parts for the A4LD? Generally I get them from chain auto parts stores but they dont' even carry the valve body gasket much less any kind of kits or servos that I can find.
Sorry for the late reply, by the way. I really appreciate all the help :)
 

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Discussion Starter · #6 ·
Thanks for the info, guys! I ordered some parts and they're in the mail. In the meantime i've dropped the pan and noticed some metal shavings in the bottom, but no pieces of bands or anything so that much is good. Thinking part of my problem may be a clogged valve body? I'll drop the valvebody once I get the parts/rebuild kit in the mail.
 

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Discussion Starter · #7 ·
Okay so my parts have arrived and i've dropped my valvebody and noticed something interesting. Where theres supposed to be 2 solenoids side by side (3-4 and torque lockout) there's only one there (i think its the TCC). This isn't right, correct? I was looking up more manuals and pictrres and everything I found says theres supposed to be 2 side by side. I'm at a loss here. (if it helps I'll take some pictures and post them)

I was thinking and i remeber when I bought the car, the owner said that the original transmission had burnt out and he replaced it with one from a 93 (i think? early 90's i know). Could it being a newer transmission have anything to do with it? I think I read somewhere that they may have been slightly different (like 2wire vs 3 wires or something) Any ideas?
 

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Like said I don't know. I found a a4ld manual on this page. May or may not answer your question. TRS Transmission, Transfer Case & Driveshaft Library
Maurice
Edit done some reading seems the earlier trans was a single solenoid and later 2nd was install. Well that is best of my reading. Maybe the manual in the link will help.
 
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