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VA Chapter Director
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Discussion Starter #1
My girlfrinds son's 95LX V8 had a bad transmission. When in drive it would hold first gear, even when at light throttle, to about 4000rpm. If you put it in 1 then the car would not move and acted like it was in park.

So I got a used 50K transmission with a shift kit in it and installed that that other day. Now the car idles fine, and if you just barely touch the throttle ( probaly about 5% throttle) it will run ok but if you push the throttle an more that that the car bogs down and will not acclerate. It dosen't stall but the tach won't climb. If you back off of the throttle it will then smooth out and climb but very slower because you are just barely on the gas. The check engine light was also on.

Now.
When we drove it home from doing the tranny install we did not have the passenger side exhaust connected to the manfold because we had to twist off the rusted exhaust manifold studs at the collector.
I figured the problem was that one bank was running rich since the O2's on that side were not getting exhaust flowing over them.
I had the exhaust repaired today and the car still drove the same. Still has the Check Engine light. I got the car home and disconnected the battery for about 20 min. Now the check engine light is gone but the car still runs the same.

Could I have missed connecting something on the new transmission that would cause this? The car does the same thing if I put the car in Park and try to rev the motor so I don't think there is a problem with the new tranny.
Is there a way to pull codes on the cars with the ECC V? I've only had SC's so I don't have any experience with that computer.
 

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ya you can run the codes on a 95. im assumeing that the car didnt do this befour the tranny swap but how long was the car sitting in between tranny swaps
 

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Check your TPS and MAF
 

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What year transmission did you install? If it was anything but a 94/95, you must change the TCC solenoid first. Failing to do so can cause all sorts of problems and possibly fry the ECM.

Check over everything to make sure you didn't leave anything disconnected.
 

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P1747 is for the EPC solenoid. If this solenoid isn't working, the trans ain't gonna move. Check the wiring harness that plugs into the internal harness and also check the harness inside to make sure everything is fine. You may need to swap the solenoid with your old one.
 

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VA Chapter Director
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Discussion Starter #9 (Edited)
P1747 is for the EPC solenoid. If this solenoid isn't working, the trans ain't gonna move. Check the wiring harness that plugs into the internal harness and also check the harness inside to make sure everything is fine. You may need to swap the solenoid with your old one.

Can you define EPC for me? (Nevermind, found it Electronic Pressure Control )

The car will shift through gear 1, 2, and 3 ok. It will not go into OD.

Could this be a bad MLPS? I have the old one from the other tranny I could swap in.
 

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Here is what I found this means.


Here is the Definition of your Diagnostic Trouble Code (DTC)

Make Ford
Year 1995
Model Thunderbird


Diagnostic Trouble Code (DTC) P1747
DTC Definition: Pres Cntrl Sol. A Circuit Shorted
That's the EPC solenoid. It controls the main pressure in the transmission out of the pump. If it's too high, it will blow seals, too low, no engagement.

Sounds like it isn't high enough to shift, and isn't doing the 1st gear engagement correctly, and is in between gears. (or two at once...)

I'm not positive, (Someone please correct me if I'm wrong!!!) but I believe the transmission will work completely unplugged, and only give 2nd gear as a limp mode. Trying this will eliminate electronic issues, as far as I know. It will not correct any internal malfunctions, just verify electrical vs mechanical.

You may have a wire bolted between two pieces of metal...if everything worked before, in both cars.
 

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VA Chapter Director
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Discussion Starter #11
It seems to engage each gear 1 - 3 fine as long as you are only very slight throttle.

I replaced the MLPS with the one from the other transmission. Still have the same problem.

The part you want me to unplug, is that the big white plug that looks like it plugs into the top of where the valve body is?
 

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If you unplug it and you have second gear just fine, then you know you have an electrical problem inside, most likely with the EPC solenoid.
Exactly; But, the transmission should work correctly with all throttle settings, only it won't shift.

If it still bogs down at more than partial throttle, the EPC being bad possibly isn't your major problem; The transmission might not be the year you think it is, which can cause problems with the EEC. A shorted EEC wire can also cause issues like this.

If you now still have the same behavior, you know for sure that you have to open up the tranny. Before I did that, I'd measure the resistance of all the solenoids; If they all match, the EPC solenoid is likely bad. If they are different, your eec may not be driving it correctly. If a wire is shorted; it's in a flange, bolted down somewhere. :D

Unplugging the connector is a drag, but losing $50 in mercon V for nothing is worse for both your wallet and the planet. (I am cheap AND Green, kinda like a martian hooker...)
 

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Discussion Starter #14
Well I do believe the trans is out of a 94. When I took the MLPS off it idid not have the orange around the edge like the 95+ ones did. I'll try to unhook the harness tomorrow after work and see if it will just run in second gear.

I wonder if it's possible if runnign the car with the open exhaust manifold if we melted some wires going to the harness?
 

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Discussion Starter #15 (Edited)
So today I unpluged the white plug that goes to the tramsmission. Just as somone guessed the car goes right into Reverse and when put in drive it stays in 2nd gear. It runs smoothly in both reverse and second gear.
So now what do I check. I assume the problem is eather in the wiring leading to the transmission or in the wiring inside the transmission it's self. I'm thinking that since it did not do this with the old trans that it is most likley in the tranny. Is this something I can just drop the pan and do? Does anyone know how I can check this? Anyone know where I can find a pinout diagram?
 

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As I mentioned above, your best bet is to swap the EPC solenoid out with the one from your other tranny if there were no codes when that transmission was installed. You will have to drop the pan, but you will have to be doing so regardless to check that all the wiring is in good order. Did you use the wiring harness that goes around the outside of the transmission from the old trans or this new one? If you used your old one, then I wouldn't worry, but if you used one that came with the trans, there could be a problem in that too, so you might want to swap that first. You wouldn't have to get into the pan.
 

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VA Chapter Director
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Discussion Starter #17
I used the harness that was already on the car. Unfortunaly I don't have the old trans any longer. I was told that this one was in good working order when I got it so the other one was taken to a salvage yard by a friend who was avaiable and had a truck.
Does the valve body need to come out to replace the EPC solenoid or just take the pan off?
 
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