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Discussion Starter #1
I have a p0712 code and the OD light is blinking. (TFT sensor circuit low input). The harness looks okay, so I figure I need to replace the sensor. It requires a pan drop, right? I know on my 2000 it is part of the harness, but not on the 97.

Until I get it replaced, how much does this affect shifting and lockup?

This is a new to me 97 Mark VIII with 111k miles. I was playing around with using the brake and seeing if my rpms went up (TC unlock) and it didn't seem like it did, or wasn't as obvious as my 97 Cougar. It also seems to take a long time to shift, it doesn't seem to neutral out, just hang/slide from first to second, same with second to third. I haven't really tried D to OD all that much but it seems to do the same thing.

I don't really remember the 97 Cougar doing this, but I also did the JMod and got a tune for it within a month or two of getting it. I can't feel the shifts in my 2000 grand marquis so I don't want to compare it to that. I don't want to do a pan drop and just replace 4 quarts of fluid/filter and the TFT, I want to drop the VB, do the JMod, check the accumulators and springs, but I already have too many projects going.
 

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Yes, to change that sensor, you have to drop the pan - it's clipped to the bottom of the valve body. I tried to find a pic, but this is the best I could do after a few minutes of searching:

 

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Discussion Starter #3
Okay, yes I need to fix the dash, and yes it needs front end work, but lets focus on the transmission :)

I have to try to find a place to do a half throttle or higher 2-3 shift, but that happens at over 70, so I need to set it up better.

This is a full throttle run, up a consistent hill about... 6 degrees. It shows the most troubling thing I face. If I let off the throttle at the 2-3 shift it neutrals out. I have an Audi that thought I was racing it so I had keep in it because I had to merge to one lane before the interstate.

http://youtu.be/UHMvikhKggk?t=13s

This is a part throttle run.
http://youtu.be/6nlvDNRDRwU

This is a half throttle run with OD off.
http://youtu.be/53DvcX_hMyM

This is manually holding second, it has engine braking.
http://youtu.be/4P9kqHJ9Wvs
 

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Discussion Starter #4
I have the TFT, accumulators (not sure if mine has the old style or not already), a Robert JModed plate on the way.

If I stay away from full throttle then backing off at 2-3 shift then it seems fine, just a little slow to shift (something the Lightning guys like, the slide shift).
 

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Seems like a normal aged sluggish 4R70W to me. J-Mod will fix what you're experiencing.

As for holding it in 2nd, Ford trannies are different from other manufacturers in that Manual 2nd will STAY in 2nd no matter if you stop or not. Others start off in 1st anyways, but not a Ford - it starts from a dead stop in 2nd if in manual 2nd.
 

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Discussion Starter #6
Yeah, I didn't expect it to shift, I wanted to show that it didn't freewheel when letting off in manual second. I think that proves that the OD band is working even if just a little. I don't remember what it proves to tell you the truth :)
 

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Discussion Starter #7
The 2-3 accumulator seemed wedged in there, I had to pry it out.

The 2-3 accumulator retainer wasn't seated correctly, the part that hits the disc on the vb plate is really worn at an angle, and there are scars from something on the top/spring side.











 

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Discussion Starter #8
So dropped the pan, drained the torque converter, replaced 1-2 and 2-3 accumulator (already had updated steel/bonded piston) removed lower 1-2 spring, no 2-3 spring, Roberts drilled plate for 350+ HP, new Sonnax pressure regulator, boost valve, new temp sender, 13 quarts of new fluid (SuperTech Walmart brand, don't hate).

Doesn't shift as good as my 97 Cougar, but all issues are solved:

- neutral out when letting off at 2-3 shift from WOT FIXED
- partial throttle skip 3rd (or be there for fraction of a second) FIXED
- s-l-i-d-e into second gear, FIXED 90%, still a little slow and doesn't chirp the tires, they are 215 wide, my 97 Cougar would chirp one or both 255s.

This is the same on ramp as first video. I had to back way off to merge into traffic (I let it go into OD, then disabled it, then manually selected 2nd)

http://youtu.be/EYHPTruEDio

http://youtu.be/gcaIHfB2UkI
 

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Discussion Starter #9
So...still getting the P0712 code after swapping the TFT (or is it TOT?). The transmission to chassis connector seems fine, it was a little cruddy and fluid soaked, but I cleaned it up.

I guess there is something wrong with it anyways? I didn't do anything with the internal harness, it looked okay too, as did the connector.

Any ideas? I think it is affecting the TC locking up, I am not getting lockup when I think I should be, I haven't tried data logging yet to see if it is being commanded or not, I guess that is next (I have just been tapping the brakes while maintaining throttle position where it should be locked up).
 

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The TFT sensor will affect EPC pressure as well as shift and torque converter lockup schedule. The TFT sensor is wired in series with the Output shaft sensor.

When you get a code for circuit low input, this is usually a short to ground. A high input would be an open circuit.

I would start back probing from the PCM and determine where there may be excessive resistance in the wiring, look for a short to ground or a bad OSS sensor / connectors, etc.
 
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