How to remove and replace automatic gear shift assembly

Ford Falcon (BA)<< real name.
produced by Ford Australia from 2002 to 2005. no engine told of 5. non turbo right?
no vin told
no country told (down under?) we dont do cars down under.
no year car told
A/T box failures.vary by all that.
4-speed automatic BTR
guess 4.0L engine with ?????
M93LE box???? if yes, it must be OBD2 scanned. generic, last shifts are caused by.
reverse works ok
Low works ok, PRNDL
only Drive fails. and is only 3>4 shift (late and harsh)
causes are bad shift solenoid,
VSS errors
there is no Governor , the TCM does the shifting based on engine load and RPM and VSS sensors. so of engine fails, it will not go to 4th gear. correctly or late..
or if tranny has a TV cable if present.bad. rusted and stuck out.

you failed to scan the PCM/TCM
using a OBD2 scan tool. but Australia is 2006 up compliance.,
no year car told at all making any exact answer super hard.
but here is a try. lacking OBD2 port only OBD1 tools work.
I guess
Falcon (Aust.) BA 2002-05V6, 4.0L BTR M93LE
bad accumulator inside box, causing harsh shifts
sticking solenoid. to 4th release 3 fails then works4. BANG
seems the TCM is confused. if 2 boxes fail.
TCM must be scanned as the service manual directs.

A detent is a notch or notches in a part used to keep a shifter (in this case) at a certain position. Be that an automatic or stick-shift. You can imply that the shift pattern on a stick-shift has detents for each gear as the shift lever locks and slides in and out of each position for that gear to work when the clutch is released. The detents on an automatic can resemble "steps" which engage a different gear or series of gears(drive) when a certain step is locked into position by a pressure bar or pressure lever.

Sometimes the pressure bar or pressure lever is spring loaded and your hand works against that tension to select a gear or function(drive). There may be an adjustment for the spring tension, or the spring is too weak and the shift assembly must be replaced.

With electronic shift solenoids, some of the shift assembly is different than with the old-style mechanical shifter. The action may be fly by wire with electronic shifts.

I do not know what you have, so there may be differences.

If you have a stick shift ( floor shift) remove the boot around the gear stick and the insulation on the floor to reveal the 4 bolts that hold the shift turret on to the top of the box. Undo the bolts and lift the gear lever assembly out of the gear box.

There will be 4 bolts on top of the gear box that fix the gear selector turret in place . Remove any trim and rubber boots to get to these bolts . undo them and lift the gear lever ass. out of the box.

For car not changing gears it can be shifter assembly issue, or it can also be transmission issue. Get the shifter assembly inspected with ignition OFF.

For more troubleshooting, I suggest you to get the Following help link checked, its complete step by step procedure to inspect gear shift issues: -----

GEAR SHIFT ISSUES

http://alltypesofpartsreplacing.blogspot.com/2012/11/gear-shift-issues.html

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These will help.
Thanks.

What is the problem with the gear shift assembly and is it a automatic or stick?

gear shift selector roll pin that holds shift lever in postion shift rod shift rod pivot and spring assembly, colomm retainer assembly pin for shift lever lower and shift linkage lower.

I only have 2003 Nav procedure. Maybe get used part at car-part.com. Page with * is lowest price.

SECTION 307-05: Automatic Transaxle/Transmission External Controls 2003 Expedition/Navigator Workshop Manual
REMOVAL AND INSTALLATION Selector Lever —Floor Shift Removal and Installation

1. Lift the floor shift PRNDL bezel.

1. Disconnect the PRNDL bezel wire harness connector.

1. Remove the shift lever handle and cover.
   1. Slide the handle bezel down.
   1. Remove the screw.
   1. Disconnect the TCS wire harness.
   1. Lift assembly from the shifter lever.

1. Position the window regulator control panel aside.

1. Remove the screws and the console finish panel.

1. Remove the left side console access panel.

1. Disconnect the transmission shift cable from the transmission selector arm.

1. Remove the transmission shift cable retaining clip from the floor shift mechanism through the console access.

1. Remove the four bolts retaining the floor shift mechanism to the floor.

1. Disconnect the floor shift mechanism wire harness connector.

1. Remove the floor shift mechanism from the console.

1. Remove the brake shift interlock actuator, parking brake release mechanism and harness.
   • Remove the wire harness retainers.
   • Remove the wire harness retainers.
   • Remove the two screws retaining the brake shift interlock assembly.
   • Remove the two screws retaining the parking brake controller.

This is a common problem, I had the same issue, mine completely broke off. You can buy the new sleeve with a new rod at the dealer. The replacement is quite simple. You need to remove the upper and lower covers for the steering column, then drop the sterring column with by removing the four bolts. There are four bolts that hold the sleeve in.