Stuck in first

I have my old prerunner sitting around with the tranny not cooperating.
Since my son has a girlfriend who needs wheels (and we all know how hot girls look in prerunners!) I've decided to get it back up and running.

Its a 96 with the tranny stuck in first (it may have reverse, I'll need to check that.) This was my son's old rig and at one time I sent him out to change the oil and he drained the tranny instead (go figure, hes an engineer.) When he refilled it he did add too much ATF.

Could that cause it to not want to shift? What else can I be looking at?
Is it best to send it off to a tranny shop and have them look at it?

Any help would be appreciated. I'm sure this project will be coming out of my pocket (I'm such a nice guy!)

Rick

it could certainly cause it not to shift. Auto trannies are fully dependent on the fluid pressure to operate. Too much or too little and it will cease to function. Drain and refill to spec and retest. Fluid level should be checked/topped off with the engine running and the transmission in park/neutral.

Mine was slow to shift to 3rd[skipped 2nd]. Shifted at about 3000 until warmed up. After fully warm it started in 3rd unless manually put into 1-2. Had many codes come up and found bad solenoids in trans pan. 3 solenoids and works perfect.
Ron