91 ranger 2.3 shifting in and out of o/d or not at all

[KyleTH]

A couple days ago it stopped shifting into overdrive so at 55 MPH I run right around 4,000 RPM. Sometimes it will shift into o/d but it goes in and out repeatedly for about 30 seconds and then stays in fourth. I think it may be worth noting that the Tachometer failed a few days ago, now even if I floor it, it only goes up to about 2,500 RPM. I looked up how to read the check engine light but I keep getting lost so the video is below. It's got a few codes, not sure if they are linked to the shifting problem or not but i'd like to figure out what they are and fix it too. Thanks for the help.

The video to the trouble codes

 

[muzzlestuffer]

i had a shifting problem can't remember what gears on my tranny but took it to my tranny guy and he rebuilt the tranny and it was still doing it turned out to be the electric connector that controls the shifting it was bad replaced it then it was ok

 

[KyleTH]

any clue as to what the codes are?

 

[KyleTH]

The Tachometer is now bouncing up and down when i'm accelerating if that helps at all.

 

[Mark_88]

It may be the same thing my ancestors suffered from...missing teeth...pull the end on the transmission and have a look...comes out with just one bolt...

 

[KyleTH]

It may be the same thing my ancestors suffered from...missing teeth...pull the end on the transmission and have a look...comes out with just one bolt...

Thanks for the reply! but is this in reference to the tach issue? or the non shifting issue? or hopefully both.

 

[Mark_88]

Oh, sorry, I was thinking speedometer...and I would assume that you have a five speed since I don't recall seeing an OD option on the automatics.

The M5OD-R1 was a popular transmission and they are typically very tough...but it sounds like it may need some work. Have you checked the fluid levels lately?

The bouncing tach sounds like a loose connection if the engine is not actually fluctuating the same way. My Tempo tach started bouncing and it turned out to be the MAP sensor...but the engine also had erratic idle. Not sure if the 91 had a MAP sensor but whatever they replaced it with in later years would be where to possibly look...like the IAC...I think.