AX4S / AXODE Trouble...

[Blue Bowtie]

And it appears I'm not alone:

http://www.automotiveforums.com/vbul...d.php?t=533673

http://www.automotiveforums.com/vbul...d.php?t=534607

http://www.automotiveforums.com/vbul...d.php?t=532817

http://www.automotiveforums.com/vbul...d.php?t=529725

And an entire search page (actually, FOUR of them) regarding the same trouble:

http://www.automotiveforums.com/vbul...archid=1458455

The root cause?

http://www.ford.com - Possibly?

Anyway, for those tolerant enough to follow along, here are the specifics.

1998 Windstar GL 3.8/AX4S, 129K miles, reasonably well serviced by previous owner (or so it would appear by receipts).

I retrieved a P1744 DTC (and a P0300 - No biggie). The line pressure fully warmed is 125-130 PSIG. That appears to be in range. Low servo pressure appears to be 38 PSIG at hot idle. The front test port (between the cooler lines - Not sure what it is) is 90 PSIG regardless of selector position or engine RPM. Fluid and filter changed yesterday. Drain plug added to pan (as always). I used Mercon instead of Mercon 5 since it is definitely an AX4S, not an AX4N. They tell me that's the cutoff.

When dead cold, driving will seem normal, starting in lower range and shifting through to D. It might shift to OD, but at only 35 MPH its difficult to tell. Tach doesn't indicate so. As it warms, the trans drops form D to 2, then shifts back to D briefly, then drops back to 2, back to D, until it is reaching normal temperature and will no longer do to D.

WHILE FULLY HOT:
Trans will not even shift to second range
Manual Low (1) will engage 1;
Manual 2 is "no-man's land";
Manual D/OD causes 2nd range (default?)
Trans engages immediately to R or into a forward range (probably 2?) when selecting between "R" and "D". There is no hesitation and engagement is firm/adequate.
Disconnecting the harness connector does not increase line pressure;
Driving with the harness disconnected will allow a 1-2 shift;

I am thoroughly confused. Valve body access is impossible with the vehicle assembled (it's certain NOT a HydraMatic 4T65E) . Short of dropping the engine and cradle, what's a person to do?

I have searched archived threads, and it appears my symptoms are similar to those of a failing selector position switch, but not exactly. Only doing it hot doesn't support that - Or does it? "Nornal" shifting 1-2 with the solenoids disconnected at the valve body connector is also confusing.

If someone has a pinout of the selector switch, I'd like to verify continuity of each circuit before just slapping parts on with crossed fingers. That's not diagnosis, but part-changing.

Any help or direction would be appreciated.

[Blue Bowtie]

Just to update, suspecting the control system and not the wear surfaces, and having no schematic to diagnose the range/selector switch, I experimented a bit further.

NOTE: Those of you who suspect this switch as a problem may be interested in this information.

I started the vehicle, then disconnected the Transmission Range Switch (TRS). Since the engine and trans were already at temperature, I went for a short drive...

Of course, the "OD" indicator on the end of the gear selector lever was flashing since the PCM didn't have a clue what was going on. That was fully expected.

Reverse was normal, but it was normal with everything connected, as well as with the solenoid connector (the white one) removed. Drive engagement was fine. As I slowly drove off, it shifted very firmly 1-2, then speed increased and there was a very firm shift from 2-3. Wow! It actually DID something. (The harsher shifts are to be expected since the trans is probably operating at full line pressure - no active PWM solenoid to modulate pressures.) I kept driving, and running through the ranges. After about two miles and a fully warmed trans, it didn't miss a lick. It never went to OD, and of course the TCC never locked, but with the PCM running "blind", that's to be expected. I went back to the garage, removed the TRS, and pulled the seal at the base of the electrical connector. I poured in about 2-3 ounces of rubbing alcohol, "worked" the switch through the entire range several times with a large, flat-blade screwdriver, and dumped the alcohol and all the contamination it had flushed out. I lightly lubed the switch and replaced the seal in the connector socket. I then reinstalled and adjusted the switch, plugged everything together, and went out to burn some more gasoline.

Amazingly, everything was as happy as Henry wanted it. All shifting, OD, TCC lockup and release, decel/coast lockup, and all the functions were back to normal.

I'm off to find a new switch now. I will not trust a switch that had failed once. I would suggest that anyone doing this "test" and finding a similar solution do the same.

Thanks to Mr. Clay Cleve and wiswind in abstentia for their past assistance to other members. Their archival information was just enough data and hint to get through this. (I'd still like to have a pinout of the switch for future reference.)

FWIW - The previous owner had two shops quote a rebuild and R&R at about $1,700-1,900. A $42 switch is a lot easier, faster, and just as effective.

If you ever have questions regarding vehicles from Flint, don't hesitate to ask.

[wiswind]

This is the reason that I suggest a replacement of the TRS first.
If you can replace it yourself, it is cheaper than just a diagnostic (I paid $65 over 4 years ago) at most dealerships.

[Blue Bowtie]

Since I perform the diagnostics, and was trained a long time ago to diagnose before replacing parts, I really needed to check it out myself before any conclusions were drawn. Even if it is a $10 part, it's just poor practice. Without schematics, the process of elimination served the purpose.

Replace the TRS first, replace the vehicle second. Problem solved.

Thank you again for your previous posts. With that information and more that I was able to gather, I refrained from dropping the cradle before I knew exactly what was going on. Hopefully, this can help someone else in the future.

[lewisnc100]

Originally Posted by Blue Bowtie

I used Mercon instead of Mercon 5 since it is definitely an AX4S, not an AX4N. They tell me that's the cutoff.

Better double check since that is not the cutoff. The 1998 Windstars with AX4S used Mercon for models built before 9/9/97 and Mercon V for models built on or after 9/9/97.

[Blue Bowtie]

Thanks for the update. I'll look in the door jamb for the build date. It won't hurt to drain it for a third time, anyway. At least there's a drain plug now.

[fastfishel]

I have just finished building an AXODE shifts through all gears and has converter lock up but at 40 mph I lose all pull and rpm rev. When coming to a stop it will shift back through all gears and do over at 40 mph. Someone please help Ive had this car in garage for a month and trans out twice