90 XJ AW4 no reverse.

progressively got worse now it rarely engages into reverse. Any ideas? Also does anyone have the wiring diagram for the module and the trans range sensor? Thanks

I had the EXACT symptoms on my aw4.
As i tore into it, all the orings were no longer round. The age, and heat had made the flat on the sealing surfaces. Hardly any wear on the clutches and steels. All 3 orings for the reverse piston were particularly hard.
Mine got progressively worse, the colder it was outside. Once it was warm, went into reverse like normal
I got tired being held hostage by my trans, so i decided to rebuild it myself.

89 4x4