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Discussion Starter #1 (Edited)
97 T-Bird, 4.6, 63K, original owner.

Check Engine light came on. OBD showed 2 codes, both P1747. After doing some research here, I decided to start with the internal wiring harness (soft harness, white connector). Still had the same problem... 2 codes, P1747.

I checked the external wiring harness and the two wires that go to the EPC seemed OK... no corrosion on the connectors and no resistance.

Decided to change the EPC. While I was in there, I changed the 1-2 and 2-3 accumulator pistons and springs (went with stock parts, since I always liked the smooth shift on this car), and installed a sonnax pressure regulator valve.

Still have the same problem... 2 codes, both P1747.

What do I do next? Should I keep looking for problems inside the tranny (MLPS, or one of the other solenoids)? Or am I set with the new harness and EPC?

I'd like to check the wiring harness that goes from the tranny to the computer, but I have no idea which leads to test. Does anyone have diagrams of the pin layouts for the two ends of the harness?
 

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Discussion Starter #2
Just tinkered with the old EPC. I gave it some juice from a 12V battery. I would expect to see some sort of movement (looks like there's a shaft inside), but nothing happens. It makes a popping noise, but I don't see anything moving.

What should happen when power is applied to the EPC? I'd like to figure out if this unit is bad and was part of my problem.
 

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Discussion Starter #3
Still having no luck with this.

The problem went away for a little while, but it's back again.

I isolated the two EPC wires at the PCM connector and connected a volmeter while driving. The hot lead was pretty consistently ~13.5V when the car was working and also when the O/D light was flashing. The return lead was a different story... when the car works, the return starts out with ~10.4V and as the car warms up, it gradually drops to ~9V. Now that it's acting up again, the voltage is all over the place, dropping to ~9V and spiking to ~13.5V. I'm guessing the voltage spike is what causes the O/D light to flash.

I'm starting to think that the tranny is fine, but the PCM has a problem. Can anyone confirm my suspicion or tell me what else to check?

Anybody have a good PCM for sale (part #F7SF-12A650-BB)? Not looking to spend a lot, since I have no idea if it will solve the problem.

Are there any other PCM part numbers that will work on this car (97 T-Bird 4.6)?
 

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Still having no luck with this.

The problem went away for a little while, but it's back again.

I isolated the two EPC wires at the PCM connector and connected a volmeter while driving. The hot lead was pretty consistently ~13.5V when the car was working and also when the O/D light was flashing. The return lead was a different story... when the car works, the return starts out with ~10.4V and as the car warms up, it gradually drops to ~9V. Now that it's acting up again, the voltage is all over the place, dropping to ~9V and spiking to ~13.5V. I'm guessing the voltage spike is what causes the O/D light to flash.

I'm starting to think that the tranny is fine, but the PCM has a problem. Can anyone confirm my suspicion or tell me what else to check?

Anybody have a good PCM for sale (part #F7SF-12A650-BB)? Not looking to spend a lot, since I have no idea if it will solve the problem.

Are there any other PCM part numbers that will work on this car (97 T-Bird 4.6)?
This place has one F7SF-BB for $69 under stock number CCT095 listed on car-part.com:
http://www.mrautosalvage.com/

Good luck with it!
 

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1997 Thunderbird 4.6, 1998 Mark VIII LSC
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The variation in the last two digits designates the catch code. FTE0, FTE1, MBE1,2,3, NPL2 and NPL3 are all interchangeable for 96/97s.

I cannot, however, offer any other insights into your problems.
 

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Discussion Starter #7
The variation in the last two digits designates the catch code. FTE0, FTE1, MBE1,2,3, NPL2 and NPL3 are all interchangeable for 96/97s.

I cannot, however, offer any other insights into your problems.
I appreciate any help. I'm not sure this will solve the problem, but it seems like I should be looking outside of the tranny for the problem.

Sounds like I can use the part from any 96 or 97 with a 4.6. I found a good deal on the ECU from a 96 Cougar (part # f6sf-12A650-Ac)... will this work?
 

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Discussion Starter #8
OK... swapped the ECU and it looks like the problem is solved. Car was acting up right before the swap and worked perfectly right after. I'll have to drive it a few times to be sure, but I think this is it.

FYI - original ECU was F7SF-BB (LJC1); replacement ECU is F6SF-DB (NPL1).... seems to work without a problem, even though a few parts sellers said it wouldn't work unless it was an exact replacement.
 

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If my original PCM has a dyno tune on it, and i need to replace it, how would i go about that? does it have to be dyno tuned? or can i reburn the dyno tune file into the new pcm?
 

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1997 Thunderbird 4.6, 1998 Mark VIII LSC
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Also assuming that the programmer was also initially used to flash the current tune to the vehicle, of course. :)
 

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i got an Xcal2, tuner used that to load the dyno tune into the PCM....xcal says 5 tunes left!
 

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To grumpy steven what exactly was the problem that you was having with the trans. I am having a problem where it won't shift past 1st and i would have to shut off the car and then when i restart it works normally. Is this the problem that you were having?
 

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what is the EPC you guys are talking about? my car is throwing a p1747 code now, but no flashing OD light. I may buy a new computer this weekend to try. But want to know what the EPC is so i can check it. Search feature doesn't show any results for EPC.

Edit: I found out what it is, but now where is it? I am having trouble figuring out where it is. I found the tranny article and it helped a lot. i just need to know where it is in case I have to replace it.
 

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1997 Thunderbird 4.6, 1998 Mark VIII LSC
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Drop the trans pan, it's attached inside a recess above the fluid level to the side of the worm tracks in the transmission case near the 1-2 accumulator. It doesn't attach to the valve body; the last connector in the trans harness terminates at it.
 

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Thank you! I am going to have to check it as well as my computer. My issue started when I jumped the alt fuse one night to get home. I am sure I fried something because the check engine light came on after I jumped the blown fuse. I know it wasn't the best thing to do, but I was stuck and needed to get home. I put a new alt on the next day. I do get a ceck engine light with p1747 however my OD ligh does no flash. The OD switch is currently not hooked up in my shifter handle though. I need to fix those wires. I will try to find a 94 bird or cougar in the yard this weekend and grab another computer. Never hurts to have a spare laying around in case that's not the problem. If not I guess I will drop the pan and put I. A new EPC and do my jmod a little sooner than I had planned.
 

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I can't edit my above post on my phone so I had to make a new one. My car is a 94 cougar 4.6 but has a 96 tranny in it. My dad said he did not change any of the electronics in the tranny 2 years ago when he changed it out. Any idea what computers are compatible in a 94?
 

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1997 Thunderbird 4.6, 1998 Mark VIII LSC
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My dad said he did not change any of the electronics in the tranny 2 years ago when he changed it out.
Well that's a problem right there. Whenever you swap out to a different year transmission, you have to at least use your original TCC solenoid and MLPS.
 

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It seems to have worked ok for the las 2 years but I had planned on changing them back to 94 pieces anyway. So that will definatley be handled with the everything in the tranny as well as a jmod. Any idea though what computers are compatible with 94. I notice you posted above the 96-97 computers that were all interhangable. If it isn't my computer I like to have an extra known working computer on hand in case I ever need to rule that out anyway.
 
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