Here's How:
Haynes Ford Taurus/Mercury Sable Repair Manual 1996-2001; page 7-1
QUOTE
These models use one of two electronic 4-speed automatic transaxles; the AX4N and the AX4S.... To identify which transaxles is in your vehicle, look on the identification tag attacted to the top of the bellhousing....The end cover and the oil pan on some transaxles are stamped AXOD, which is an older name for the AX4S; the two are identical. (I have a 2000 and mine even says AXOD)
Shifting on these transaxles is controlled electronically. Utilizing data from the network of information sensors, the Powertrain Control Module (PCM) determines the best shift point for the particular driving situation. Shifts occur when the PCM grounds the electronic shift solenoids inside the transmission. No vacuum controls, TV cables, or other mechanical devices are employed.[/b]
Now for all that in english.
What that means is that there is nothing mechanical that you need to "fool" into keeping the tranny in 2nd gear, or any other for that matter. Everything is electronic, and that makes this idea 10x easier. There are no valve bodies, throttle cables, or anything else to have to monkey with. Now if you look on pages 12-23 to 12-25 you'll see the schematic of the PCM system. If you hardwired into wires 3/7(PPL/ORG) for shift solenoid #2, wire 4/8(ORG/YEL) for shift solenoid #1, and wire 6/10 (PNK/BLK) for shift solenoid #3, you could manually operate the transaxle and override the PCM and would only have to shift into OD (because all gears would be available in OD). A couple issues though....
1) You would have no idea about if the PCM includes a delay time between shifts.
2) Logic would say that when the PCM grounds shift solenoid 1, it would shift to 2nd gear, #2 for 3rd, and #3 for OD (torque converter clutch TCC is independent meaning you could hardwire that also so you could have OD but no locked up TCC), however.......
3) What about downshifts and reverse?
4) The gear selector has NOTHING mechanically associated with the transaxle (besides the PARK locking pin). All it does is move an arm that moves a variable resistor that the PCM reads as the transaxle range/gear (R, N, OD, D, 1).
5) You have to throw out idea #2 because you have SIX gears and only 3 solenoids (1st, 2nd, 3rd, 4th, N, and Reverse). Now logically if you have no solenoids powered, it should default to N. That one's easy. The trouble is which solenoids need to activate to give you the particular gear? And more importantly, which ones do you NOT want to activate because you'll eat the tranny?
So, here would be your plan of action....
Hardwire with relays into the 3 shift solenoids and a switch directly onto the TCC solenoid. For the TCC, the switch HAS to be ON for the TCC to lock up, otherwise it gets no power. This would be good for having 4th gear with no TCC. It leaves the computer the decision as to when to lock up the TCC, but you have a manual override over it. On the 3 relays (make sure they're low impedeance relays, you don't want to pull too much current away from the solenoid) and wire them into LEDs or lights so you'll have 1 light for each solenoid (labels her come in handy). Then as you drive the car, you can watch solenoids are active in what particular gears. You then can understand the shifting pattern of the tranny and then hardwire into the shift solenoids to manually control the shifting and take the PCM out of the equation. In looking at the schematic, there are no sensors that tell the PCM if it's fired the solenoid or not. It just goes for it and thinks the solenoid's doing it's job; however there may be programing in the PCM to check it.
Then once you have the LEDs wired in, you can modify it to have switches accompanying the LEDs to manually control everything.
NOW, how would you do all this? Instead of running tons of different wires, just run a single wire like a CAT 5 ethernet cable (8 wires, 4 pairs) or a 5 pair wire (you'll have a pair for back up). Then wire everything together into a control box of sorts that would not only give you manual control, but also give you a way to still let the computer work when you don't want to. Thus, you can control the shifting manually on the track, yet still not have to worry while you're driving to grandma's. Have fun.
-mobiuslogic
