At a loss
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Junior Member
Joined: Feb 2018
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At a loss
2004 heritage. So basically an 03
last week I got P1747 EPC solenoid short. Along with many other codes
i went and pulled a wiring diagram and a fuse diagram and ended up finding a 15A fuse under the hood blown. Replaced it reset the check engine light. For the last WEEK the truck ran fantastic
went to go to the store tonight. Overdrive light starts flashing. Truck runs like a bag of isht
same codes as before.
If if it were a shorted wire the problem WOULDNT go away. The fuse isn’t blown either
am I chasing a bad computer?? Thanks folks
last week I got P1747 EPC solenoid short. Along with many other codes
i went and pulled a wiring diagram and a fuse diagram and ended up finding a 15A fuse under the hood blown. Replaced it reset the check engine light. For the last WEEK the truck ran fantastic
went to go to the store tonight. Overdrive light starts flashing. Truck runs like a bag of isht
same codes as before.
If if it were a shorted wire the problem WOULDNT go away. The fuse isn’t blown either
am I chasing a bad computer?? Thanks folks
Senior Member
Joined: Jun 2016
Posts: 279
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From: Ipswich, UK
It could be an intermittent short, all it takes is for a wire to be rubbing on something to wear through the outer casing and then a bump in the road could make it move and short out enough to blow the fuse
I would be looking at the harness that goes to the gearbox, I'm sure there was a thread recently with that having rubbed on something
I would be looking at the harness that goes to the gearbox, I'm sure there was a thread recently with that having rubbed on something
Thread Starter
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I’ve looked at the harness as best I can. It goes from the firewall to behind the motor and that’s as far as I can see it. I don’t feel any chaffing behind the head where the loon touches the actual head itself. Also the harness appears to run on top of the transmission where it can’t be seen
the fuse isn’t blown this time but a week ago it was and once I replaced it and cleared the codes it was fine. I’m wondering it the computer is bad and after X kilometres it does a self diagnostic and then goes into limp mode
the fuse isn’t blown this time but a week ago it was and once I replaced it and cleared the codes it was fine. I’m wondering it the computer is bad and after X kilometres it does a self diagnostic and then goes into limp mode
Senior Member
Joined: Apr 2014
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From: Indiana
I'd suspect an intermittent short as well but if you want you can easily test your theory. Replace the fuse, reset your trip odo, write down the kms when it blows, put new fuse in, reset odo, and see if it trips at the same interval.
Senior Member
Joined: Apr 2014
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From: Indiana
Originally Posted by FordGuy89
I’m going to try that tonight. The truck sat for almost three months and previously didn’t have this issue. I don’t really think sitting doing. Nothing could harm it. But again I could be wrong.
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As far as I can see. There’s no animal damage unless it’s on top of the transmission where the harness leads to. And where I can’t see.
Its odd odd to me that after a whole week of driving to and from work. To various other places that last night five minutes out of my driveway it did this again.
I live on backroads that arent aren’t the best paved and have many potholes. I would have thought driving over those bumps and things would have shorted it long ago
Its odd odd to me that after a whole week of driving to and from work. To various other places that last night five minutes out of my driveway it did this again.
I live on backroads that arent aren’t the best paved and have many potholes. I would have thought driving over those bumps and things would have shorted it long ago
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2001 4.2 L XL 2wd. 4r70w
A couple months ago I had a P1747. I was driving at about 50 mph and it suddenly down shifted out of overdrive, the OD light started flashing and it ran like crap.
I later learned that P1747 tells the PCM to limit torque in the engine to prevent/minimize damage to the transmission when the EPC solenoid is not working properly.
I spent days of looking for a short or any electrical problem with nothing found. So I broke down and decided to replace the solenoid. Since I didn't want to have to drop the pan multiple times I replaced all the solenoids and the hard wiring harness. I filled it and fired it up and immediately got the code again.
I had tested and compared the resistance of the old solenoids to the new and there was no difference. I think the factory manual wants you to test the EPC resistance with the fluid hot, but I didn't do that.
According to the troubleshooting procedure the next step when the solenoid tests good is to replace the PCM. So I replaced my PCM. I used forscan to reinitialize PATS and make the new PCM play nice with the rest of the modules. I had to get the free special license to work with PATS. You need at least two keys if you mess with PATS.
Now the truck runs and shifts better than ever.
A couple months ago I had a P1747. I was driving at about 50 mph and it suddenly down shifted out of overdrive, the OD light started flashing and it ran like crap.
I later learned that P1747 tells the PCM to limit torque in the engine to prevent/minimize damage to the transmission when the EPC solenoid is not working properly.
I spent days of looking for a short or any electrical problem with nothing found. So I broke down and decided to replace the solenoid. Since I didn't want to have to drop the pan multiple times I replaced all the solenoids and the hard wiring harness. I filled it and fired it up and immediately got the code again.
I had tested and compared the resistance of the old solenoids to the new and there was no difference. I think the factory manual wants you to test the EPC resistance with the fluid hot, but I didn't do that.
According to the troubleshooting procedure the next step when the solenoid tests good is to replace the PCM. So I replaced my PCM. I used forscan to reinitialize PATS and make the new PCM play nice with the rest of the modules. I had to get the free special license to work with PATS. You need at least two keys if you mess with PATS.
Now the truck runs and shifts better than ever.
Thread Starter
Junior Member
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So you think mine is a PCM problem too? Because if so that’s gonna suck.
I haven’t checked the EPC solenoid but I have checked the wiring harness and the fuse was blown last time but not this time. As far as I can see the fuse is fine.
Im about at wits end
I haven’t checked the EPC solenoid but I have checked the wiring harness and the fuse was blown last time but not this time. As far as I can see the fuse is fine.
Im about at wits end
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Joined: Mar 2018
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It *could* be the PCM. I wouldn't jump to swapping the PCM until after testing or replacing the solenoid. The test procedure is to get the trans up to temp then test the the resistance of the solenoid. You can get the expected resistance value and the transmission connector pinout from google.
Or you can swap out the solenoid, but you have to drop the pan and loosen up the shift rod to get to it. There are some youtube videos that show it as part of rebuilding a 4r70w. It took about an hour and a half with me moving slowly.
Or you can swap out the solenoid, but you have to drop the pan and loosen up the shift rod to get to it. There are some youtube videos that show it as part of rebuilding a 4r70w. It took about an hour and a half with me moving slowly.