As the engine warms up the transmission does not shift into drive or reverse?

So, you wouldn’t recommend just changing the solenoid? I mean, it’s cheaper than replacing the transmission fluid and filter. But yes, if you could send me some directions on how to change the fluid and filter, I would appreciate it.

Would the Innova 5610 code reader be capable of doing the bi-directional test of the solenoid?

It is bi-directionable. As long as it is, it should work? Or no?

Okay, I removed the transmission pan and filter. I will enclose pics of what I found. My questions are as follows. Is any of this normal? There is a layer of trans fluid/black sludge at the bottom of the pan. What’s the best method to clean it up? Solvent? Brake cleaner? Carb cleaner? The filter itself is supposed to be black plastic on one side and silver metal on the other. Is it normal for the silver side to be black with sludge? The filter itself appears black, is the normal color supposed to be white when new? Lastly, one of the enclosed pics is of a white round plastic ring which was on the neck of the filter that attaches to the transmission. Is this the o-ring? I was expecting something rubber for an o-ring, but found nothing on the filter or left behind on the transmission resembling an o-ring. Thanks in advance. I already plan on replacing the filter and trans fluid that came out during removal. Please advise.

Here’s the pics. Another thing, do you know the torque for the pan bolts when I reinstall?

Okay, you may have missed this question. Do you happen to know the torque for the pan bolts?

Okay, sorry it took a while for me to get back to this. This car is a project and sometimes other things take priority, lol! Anyways, the filter and fluid changed. The car now drives around my property at will. I took it on the road for a block or two, mind you, I have no plates and the title still isn’t in my name, but I didn’t like the way it was shifting. Seemed clunky at times. It appears the fluid and filter were the main culprit, but now I’m afraid the damage has already been done to the clutch plates. Is it possible, as the car is used more, mind you, it has sat for a year on my property and at least as long on the person I obtained it from property, that the shifting will become smoother?

Everything works fine now. Took the car out on the road to perform an “Italian tune up”. Thanks for your help.

I had never heard of the term until recently. My son dropped it on me. Apparently, it’s an actual thing with a Wikipedia description, lol
Italian tune-up is a slang automotive term for attempting to restore engine performance by driving a car at high engine speed (RPM) and load.

The term originated from Italian mechanics in the 1950s using this practice to burn off carbon deposits from the spark plugs of sports cars.[1][2] However, modern direct injection and port injected engines and electronic ignition systems have rendered Italian tune-ups obsolete for that particular purpose.
You learn something new every day, lol! I guess you can charge whatever you want for it, lol