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post #1 of 7 (permalink) Old 10-12-2010, 02:58 PM Thread Starter
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97 T-Bird Tranny Harness

I keep getting code P1747, which indicates a short to the Pressure Control Solenoid. After reading a few similar stories, I decided to go with what seemed to be the most common solution... replacing the internal harness (soft harness/white connector). The fact that almost every parts dealer is out of stock made me think replacing this part was sure to fix my problem.

New part is installed, and I still get the same code. I guess the next thing to check is the outside harness. Unfortunately, I can't see where the harness goes. Does anybody have some photos of the the underside of the car with the transmission removed? Or can someone tell me where the harness goes? I'd like to be able to remove it or at least pull it up to inspect all the wires.

Not sure if it means anything, but the problem seems to occur mostly when the car is hot. After replacing the internal harness, I drove about 5 miles without any problems. Tranny started acting up and O/D light started flashing just as I was getting home.
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post #2 of 7 (permalink) Old 10-12-2010, 08:11 PM
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Originally Posted by grumpy_steven View Post
I keep getting code P1747, which indicates a short to the Pressure Control Solenoid. After reading a few similar stories, I decided to go with what seemed to be the most common solution... replacing the internal harness (soft harness/white connector). The fact that almost every parts dealer is out of stock made me think replacing this part was sure to fix my problem.

New part is installed, and I still get the same code. I guess the next thing to check is the outside harness. Unfortunately, I can't see where the harness goes. Does anybody have some photos of the the underside of the car with the transmission removed? Or can someone tell me where the harness goes? I'd like to be able to remove it or at least pull it up to inspect all the wires.

Not sure if it means anything, but the problem seems to occur mostly when the car is hot. After replacing the internal harness, I drove about 5 miles without any problems. Tranny started acting up and O/D light started flashing just as I was getting home.
I'm going to tell you what I do in those situations. When I can't possible see or trace where a wire goes in a vehicle, but I show a short somewhere, I cut the wire off an inch or two from the connector, then go to the ECM and cut the wire off a few inches from the connector and just run a new wire (soldered neatly and out of sight, of course). If you feel you're not 100% positive that's the problem, run a temp wire and see if the code goes away before you solder and run a new one neatly out of sight...

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post #3 of 7 (permalink) Old 10-12-2010, 09:44 PM Thread Starter
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I'm going to tell you what I do in those situations. When I can't possible see or trace where a wire goes in a vehicle, but I show a short somewhere, I cut the wire off an inch or two from the connector, then go to the ECM and cut the wire off a few inches from the connector and just run a new wire (soldered neatly and out of sight, of course). If you feel you're not 100% positive that's the problem, run a temp wire and see if the code goes away before you solder and run a new one neatly out of sight...
I can't even figure out where the other ends of the harness connect. I'd like to get the harness out of the car and test all of the leads with an ohm-meter. I'm hoping someone can post some pics to help me out... or maybe tell me where to look.
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post #4 of 7 (permalink) Old 10-13-2010, 10:35 AM
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Question

NO WAY I'd cut any wires - I'd have replaced the PCS / EPC while I was in there & God knows almost everything runs thru the MLPS so... ?

On Topic did you see where Ford went BACK to Wire Harness vice Printed Circuit Boards in the newest derivations of our old Tranny ?

GET OFF MY LAWN~! ... & Let's not forget guys... There's still a dead Imaginary Ex-Girlfriend out there...

Last edited by BUCK; 10-13-2010 at 03:14 PM. Reason: PCS / EPC
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post #5 of 7 (permalink) Old 10-13-2010, 11:51 AM Thread Starter
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NO WAY I'd cut any wires - I'd have replaced the PCS while I was in there & God knows everything runs thru the MLPS so... ?

On Topic did you see where Ford went BACK to Wire Harness vice Printed Circuit Boards in the newest derivations of our old Tranny ?
I wouldn't cut any wires to test them... much easier to test with a meter.

I figured out how the harness is routed and tested the EPC leads on the external harness (from the white connector to the 16-pin connector). The contacts are all clean and there's zero resistance.

I see where the next link in the harness goes up into the body of the car. I guess my next step is to figure out where that harness ends and test those wires.

I get the feeling the problem is with the solenoid. Because of the error code I'm getting, I've been looking for a wiring problem. So far, all of the wiring seems OK. Is there any way to check the solenoid with the ohm-meter? I know which contacts on the 16-pin connector go to the EPC, but I have no idea what sort of reading would be normal.

I think I'll splurge for the $50 and get a new EPC. I see an ebay seller with a Borg-Warner solenoid for $47 shipped. I've found some lower prices online (around $10 less shipped), but they don't specify a brand. Is it worth the extra money for the B-W part? Or are they all the same? I'd hate to skimp on the part and get something that won't last.
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post #6 of 7 (permalink) Old 10-13-2010, 12:48 PM
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I'm confused. I thought you said the ECU reported the signal from the transmission is a short? You mean it's in the wiring harness INSIDE the tranny pan? Ohhhhhhhhhh. My mistake. That's easy enough to swap out. I thought you meant you had a problem between the big harness plug on the transmission and the ECU plug. I've had to replace wires there before.

My boss and I go through this all the time; he picks the hard way, I pick the easy way. Case in point. We had an old E250 van in the shop last week that the heater-a/c control wasn't working. I found no vacuum to the back of the controller on the dash. My boss spent HOURS trying to figure out why the vacuum (which was under the hood) wasn't getting to the other end in the dash at the controller. I told him "watch this". I ran a new vacuum line from where the old one plugged under the hood in through the firewall under the dash to the controller on the black line (vac source). Voila, problem fixed, took all of 5 minutes.

That was my point with trying to track down shorts, opens, blockages, breaks, whatever. Why try to find it somewhere in god-knows-where when you can just run a new one and be done in 5 minutes? Makes no sense to me, but whoever listens to what I have to say anyways LOL...

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post #7 of 7 (permalink) Old 10-13-2010, 01:14 PM Thread Starter
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I'm confused. I thought you said the ECU reported the signal from the transmission is a short? You mean it's in the wiring harness INSIDE the tranny pan? Ohhhhhhhhhh. My mistake. That's easy enough to swap out. I thought you meant you had a problem between the big harness plug on the transmission and the ECU plug. I've had to replace wires there before.

My boss and I go through this all the time; he picks the hard way, I pick the easy way. Case in point. We had an old E250 van in the shop last week that the heater-a/c control wasn't working. I found no vacuum to the back of the controller on the dash. My boss spent HOURS trying to figure out why the vacuum (which was under the hood) wasn't getting to the other end in the dash at the controller. I told him "watch this". I ran a new vacuum line from where the old one plugged under the hood in through the firewall under the dash to the controller on the black line (vac source). Voila, problem fixed, took all of 5 minutes.

That was my point with trying to track down shorts, opens, blockages, breaks, whatever. Why try to find it somewhere in god-knows-where when you can just run a new one and be done in 5 minutes? Makes no sense to me, but whoever listens to what I have to say anyways LOL...
I'm getting this code:
P1747: Electronic Pressure Control Solenoid - Short circuit

I haven't yet isolated the short, which is why I'm not going to try to replace any segments of wire.

There are 3 (or more) sets of wires that complete this circuit... the internal tranny harness, the external harness on the tranny and the harness that goes from the external tranny harness into the underside of the car. From there, I don't know if there are any more connections before getting to the ECM.

I already replaced the internal harness. The external harness tests OK on the ohm-meter. If there's a short, it's between the external harness and the ECM, or in the solenoid itself.
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