95 Cougar - Transmission Problems - Won't Shift into 3rd

Hello,

Recently my 95 Mercury Cougar has been having some transmission problems. I was driving home recently when 3rd gear refused to work. My automatic transmission can handle 1st and 2nd fine, but once it hits the 45 MPH mark and tries to shift into 3rd it just sits there revving.

Before the transmission failed, it slipped a few times in previous drives, but it was only recently that 3rd has refused to work altogether.

The check engine light comes on, but has been coming on for as long as I have owned the car, so not sure if that's related. The check engine light does not stay on though, rather it just comes on when the accelerator is pressed, then goes off after about a minute. This repeats and I'm not sure if it's related to the transmission.

With overdrive turned off, I can drive the car at higher speeds, but it is not shifting into the higher gear, it doesn't even try to it seems. I can get up to around 55 MPH but then the RPMs start getting around 4,000 so I haven't pushed it past there. With overdrive on I get the behavior where it slips as if it is neutral when trying to change to 3rd.

Looking online and talking with a few mechanic friends of mine there seem to be a few things that could be wrong. I'm hoping there's a simple fix for this, but a rebuild might be necessary I suppose. I'm also wondering if this is something that will get worse or if it's something where I could continue to drive it just as-is until I get a new car, as this one only has to last me a few more months likely.

Any help is appreciated. :)

You might want to check the fluid level and whether or not it has a strong odor and what exact color it is and then report here your findings.

You might want to check the fluid level and whether or not it has a strong odor and what exact color it is and then report here your findings.

The fluid level looked good and the fluid was a light pink color, which from what I've read looks ok, making me think that it's something more serious.

That's a good sign.
I used to run a few major brand trans. shops and usually when a transmission was "slipping" that is the clutch plates or bands weren't fully engaging,the fluid would turn brownish and develop a "burnt" smell from the overheated and deteriorated friction material. At that stage the trans.was usually toast. Which brings up my first recommendation;
Don't drive it like that. It can do a lot of harm to drive even a short distance with the trans malfunctioning the way you describe.
I'm not up on most of these newer transmissions but some of the old concepts still hold. You should check the filter to see if it's clogged and at that time you can also check the bottom of the pan for EXCESSIVE metal and friction material. I say excessive because there will always be SOME of these present and there will always be a transmission shop somewhere that points to this residue in the pan and declares that you need a very costly "rebuilt" unit, which may not be the case at all.
I wish I knew more about your specific unit but I do think you should take it (tow it) to a good shop (I wouldn't use AAMCO or other big chains that are pressured from above to get a high % of people sold major repairs) and get a diagnosis. If AAMCO offers a free one still,use it but DON'T let then dismantle it or do an "inspection". They used to have a free "multi-check" but some of them now charge for this.

Is what you described the same as doing a transmission flush? So, I would have to remove the transmission fluid in order to inspect the filter? I've heard that doing a flush will either most likely fix the problem or kill the transmission.

Thanks for responding. This is helping a lot so far.

We never did a flush in my shops. Most shops and all owners manuals recommend just dropping the pan,inspecting for metal and piles of friction material, clean the pan thoroughly( leaving no lint or anything in there) change the filter and use a new gasket,refill with the recommended fluid. It's that easy. But in your case I think you better tow it to a pro.