I have a 1995 ford ranger 4.0 automatic transmission. I replaced the valve system in it to fix my 2nd gear slip and now sometimes it doesn’t shift into overdrive and the 2nd gear still slip but sometimes it doesn’t and shifts perfect. And now every time I shift my truck into reverse it takes about 5 seconds to shift into gear. Now my O/D light is on any help would be great!!!

 

If OD light flashes it means transmission codes may now be in memory, these are codes in the P0700-P0799 range, not all code readers will "see" these
But if there are codes it can help you determine if a new solenoid has failed
Ford OBD2 code list here: https://therangerstation.com/tech_li...II_codes.shtml

There are two systems in an automatic, the pressure system and the mechanical system

The Valve body and front pump(only pump) is the pressure system, you need 120psi pressure to engage Forward gears, but 160psi pressure for Reverse
This is why Reverse issues are the first sign of a pressure problem in all automatics, not a Ford thing

So slow or no Reverse means there is a pressure issue, most likely

The pressure system controls the mechanical system(the rotating part of transmission)
The valves/solenoids route pressure to the clutches and brakes(bands)
There are several planetary gears sets that are "the gears" in the transmission, the clutches engage one gear set while the Bands(brakes) hold the other gear sets from spinning
The clutches and bands wear out over time, so can slip, or not enough pressure is passed on to them from the valve body so they slip

There are test ports on the outside of the transmission that can be used to test pressure in the transmission in its various "gears"
You need a 400psi gauge to test
A transmission shop can of course test this for you, check local shops for price to do this

pressure test ranges available here, page 12: https://atracom.blob.core.windows.ne...0_web_ford.pdf