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Discussion Starter #1
Car went into limp mode. Threw code p1747 epc solenoid short circuit. Grabbed my multimeter and checked the connector outside the transmission. Epc wires show 12v. Dropped the pan and checked the wires directly to the solenoid, read 12 volts. Replaced the solenoid, disconnected the battery for a few seconds, added a couple quarts of dex/Merc, Started the car and it goes back into limp mode after 2 seconds of mild revving. Could it be the ecm? Is there anything else I should've checked?
 

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FYI, should be Mercon V, not Dex/Merc.

Al
 

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It could be the ecm; you need an rms capable meter to read the epc, it's a pwm voltage.

If it's a 97, I'd guess ECM.
 

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Discussion Starter #5
Also, there's trans fluid in the connector outside the transmission, could that be the cause of the short?
 

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Yes, old transmission fluid can be conductive.

Clean it out with contact cleaner or throttle body cleaner, and fill it with dielectric grease.

It may fix it.

If it works, I'd change the fluid; Mercon V only, regular mercon will make it slip.
 

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Discussion Starter #7
Yes, old transmission fluid can be conductive.

Clean it out with contact cleaner or throttle body cleaner, and fill it with dielectric grease.

It may fix it.

If it works, I'd change the fluid; Mercon V only, regular mercon will make it slip.
Okay so I have a can of maf cleaner, I used that and some crc dielectric grease, clears the code and it came back. I'm gonna check the ECU next.. now, I did check the connectors with a multimeter and set it to 20v with the car off but set to run. Should I have done this differently?
 

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You are not going to measure the epc signal with it not running; Datalogging is your best bet at reading it, but connecting up the wires in a way you can watch them working while carefully driving is the only direct way.

Again, it's a pwm signal, so you need a meter that can read true rms. A cheap meter will read 12V (or 5v, I forget).

As it varies duty cycle, the pressure in the epc circuit changes.
 

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Discussion Starter #9
Okay, I found the issue. The transmission harness has a connector at the bottom of the transmission on the cross member. The connector is near the exhaust so it got hot and burnt up all the wires... here's the funny part though. It took me getting another Thunderbird to figure this out. I got a 97 tbird a couple days after posting this and was just gonna junk the 95. So I'm driving around and suddenly the 97 gets a flashing o/d light and harsh shifting (had torque converter shudder before I bought it but thanks to you guys i knew it was because of the fluid. Will never use anything besides mercon v again) I got the code p0720 oss circuit. I checked underneath the 97 and saw the harness mounted at the bottom of the cross member looked like a crackhead tried to eat it. So some electrical tape and dielectric grease later (I'll be replacing it with silicone don't worry) problem is fixed. Lightbulb.
 
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