Yes, rep points for reporting back

 

Ok, I'm back. The light stayed of for two weeks this time. They're getting better! Ha. i took it back to them. They gave me rental car; a Toyota Yaris piece. I took it back up to them on Thursday last week. so they have had it almost a week. They told me they have been on the phone with the Ford Engineers and are trying a couple of different things. Ha. I can't even say this without laughing. They told them t replace the air filter. Sure enough, when the service director took the truck for a test drive, it came back on. What a surprise? Ha. i talked to them yesterday and they said they will try to have it back tome today so we'll see. He said they are going to replace the alternator and double check a couple of other things. This thing has got everybody stumped.

 

So i ended up having the rental car for 16 days total. Something like 450 bucks on their part. I got the truck back today at about 5:10. They put a new air filter, replaced the alternator (then the light came back on after them testing it.), put mine back on, did some wiring repairs and that's it. They hooked a volt meter to the speed sensor and had it ran into the cab so they could watch it if the light came back on while they were driving it. It never came back on after something like 550 miles of test driving so they called me and told me to go pick it up. When i got there the service director told me all this and i asked if they had the voltmeter on it now and he said no cause it never came back on. I told them to hook it back up and if it does come back on i'll right down the numbers. So they wired it back up and sent me on my way. I drove it probably 10 miles back to the house, got my volt meter, hooked it up so it was ready. Went back to the house and and decided to go run it to see what normal reading are. Well when i started it up and put it in reverse the o/d light started flashing and the rpms went haywire. I got the readings: on 200m it was jumping between the 20's and 50's. I let it run and the rpms were dropping then normalizing. Then they dropped so low, it just died. Well it's going back to them in the mornin. Maybe they can work with these readings. I don't even know if i had the damn thing set right. I think i'm becoming a legend there cause when i walked in they just called me "F-250!"

 

I take back everything i said about these guys. Since the little dispute with the PCM, which i apologized for bitching them out when they were just doing their job, i have had no problem with them and they have really helped me out.

 

So it's been a month and a half now, did the Ford dealer ever solve the problem or figure out what was caused the PO720 code? It seems like Ford should be embarrassed that even their factory engineers and mechanics couldn't figure this out.

 

I think it's been longer than a month and a half but they've done some more to it and for a week now, it's been fixed. They replaced half of the coils and that didn't work so they replaced the other half and that didn't work so they scratched their heads until i mentioned that it might be as simple as a battery cables. (i can't take credit for the idea, my pops told me that). That was the last time i saw them. I got it back somethin like a week ago and it has not came back on. They replaced the wire to the OSS and "worked on" (might have just disconnected and reconnected it) the positive battery cable/harness/whatever they call it. I hope they've fixed it. I think i might buy one of those graduation cakes that says "congradulations, you did it!" accross the top. ha, i think they'd get a kick out of it.

 

Ha. it's been more like 4 months. 8/14/09 was the day i took it to the dealer.

 

I've had the same issue with my 2000 5.4, I've been using your posts to help guide my mechnic as i've checked about everything I can check myself. I appreciate the fact that you've continued to post as things go along, most folks just stop after a couple of posts and you never know if or what fixed the problem. I appreciate that, I hate that it happened to you, but just to let you know your experiences have really helped others like myself out I'm sure.
I've done a lot of research on the possible RFI causes which is what I and my mechanic believe it is since we tested everything to do with the sensor and/or wiring itself. He's a ford master mechinic but also has a shop at his house where labor is half of the dealerships. He hasn't seen one like this in 25 years! Anyway, I did have my ecu sent off to florida to have it rebuilt with new components, they said the motherboard was too fried to reuse so I had to lay down another $75 bucks for another used chassis so that came to a total of $ 375.00 but it does have a lifetime warranty unlike the 1 yr warranty on the "factory" ecu, which by the way is a remained unit that they outsource to like the company I bought mine from! Not only that, but when I shipped my ecu they called me back to tell me what they found in the tests they ran and told me possible causes for why it fried the connections into the motherboard before they fixed it. They did confirm that it was highly likely to be excess signal/amperage being kicked back to the ecu from some type of electrical component, the only problem is, is that could be anything. We're still workin on it, but I beleive we're getting close. By the way the air filter thing killed me! Thats when you know they are getting REALLY desperate! Oh, by the way, if anyone reading this thread is having the same problems do not drive your truck! You are at the very least causing damage to your torque converter and more than likely your ecu! Only run it to diagnose!

Again, I do appreciate it!
Logan

 

I forgot to mention, I also ran across a little thing about the ecu wiring harnesses being faulty in the 99-00 trucks. Ford has pulled that particular TSB for some reason but it was at one time an official bulliten so maybe that could be a possible cause too. They're hard to track down too apparently, so a donor truck may be easier to find. I'm checkin some other things first but I may have to go back to it later, I'll keep posting as things move along.

 

Well.... I drove my truck to class yesterday and the od light started flashing again and it shifted hard once more. The check engine light was not on but before i left the parking lot after class i checked to see if there was a code. And there was p0720 "output shaft speed sensor." So i took the truck back up to Ford to see what they wanted to do. The labor and parts are both still under warranty. But the question i have is how long has that code actually been in the system while i never knew about it cause i have it back for two months with no problem up until now. Its not all that bad, today i'm driving the excursion-ten banger. It aint my SD, but it does ok.

 

It was the altenator....in a nutshell, the brushes had dug their way into the coil and while the altenator tested good because technically it was still working, it was also sending unwanted amperage back through my eletrical system. At some point that amperage crossed the sensor wire, making my computer think it needed to shift and over some period of time, also was responsible for frying the "motherboard" on the ecu which I had to replace.
Luckily, there is a simple test for this......start the truck...unplug the altenator wires if possible....see if it stops acting up. The battery will also be more than likely shot, if you do replace your altenator, replace the battery as well cause its probably gone. I spent $620 on the mechanic, $400 on the remained ecu from fordecu.com (lifetime warranty) and about $60 on miscellanious parts. Funny enough, both my altenator and my battery were under the 2nd of 3yr warranties, so they didn't cost me anything....well, the altenator directly cost me all of the above figures I guess, but such is life! I'm just glad to have my truck back.

 

Me too bud. I wont be replacing the alternator. I tesated it myself and it was good and the Ford dealer where i have been taking also tested it. To satisfy my need they put on a brand new alternator in which case it still did not work. But i'm glad you got it all finished and figured out.

 

I got my truck back once more, and this time, they coated the wires with aluminum stop any kind of EFI in and out. Not sure on the dates but around a week later, on my way to work, the light came on every time I stopped at a stop light which was 4 times on the 1 mile trip; then, once more that evening, with the accompanying OSS code. I took it back up to the dealer on monday. Yesterday, the service director called me to let me know that they are reimbursing me the total amount of money I have into the truck through them which is a little over $250 (they already reimbursed me the rest on previous accounts) and are going to give me the truck back; no harm no gain on my end. He said the Ford engineers are not helping them fix the problem, and obviously, they are not fixing the problem, so this is about as far as they can go. So I asked what would be the next possibility to look at. He said the toner ring would be next but if we go that route, just pulling the tranny and fixing that (if indeed it is broken) might cause more problems than it would fix. So, with that being said, they would rebuild the trans, put an improver in it, and the works which would run $12-1500. A little out of my price range to put down on hunch. He told me "This is just our next guess on what might fix the problem." So, I'm going to drive the truck and put some more miles on it and when the time comes for me to do a service on the tranny anyway, (I think 120,000) I might look into doing a whole rebuild. My cousin is a trans mech so I can go that route. He also said that stuff like this happens on the buses he works on and most of the time they can look and look for the problem, but its when something actually breaks they finally find the problem.

 

Have not posted in a long time but mine is finally fixed. I've had it back for about 4 months now, 2 1000 mi trips and no light. What it finally came down to was moisture/worn wires in the main harness to the ECU. They repaired it, drove the truck for two weeks, light came back on, took the truck back to them. Found they didn't route some wires correctly which explained the melting smell we had but couldn't find for those two weeks. They fixed the wires and it has been running great ever since. For both you guys with this recurring problem. My dealership mechanic did all the same stuff yours had working the the Ford Engineers etc. and this is what they ended up getting to. In either case, wiring issues are the hardest to find and troubleshoot, i would tell your mechanics that your problems are more a wiring issue than a mechanical piece. If they have the capability to swap parts for verification thats awesome, but charging you should be right out until they find the prob.. Anyway, i wish you luck, and hope they find the problem. Cheers

 

Reporting back on the truck and what its been doing lately. The light comes on a few times a month with the same symptoms. Lately it has been doing some crazy stuff. Not sure if it's all related but it does have to do with the trans. From Drive, the trans does not want to 1-2 shift. I could max the rpms out and still no shift (not that i would EVER do such a thing) but i does shift once i let off the throttle for 1-3 seconds. My cousin and i hooked it up to a Snap-On computer to look at some readings and saw that the EPC (electronic pressure control solenoid) was reading 5 psi all the way until i make it shift then i shoots up to 70 psi until i put it back into neutral or park and drops back down? Any idea if the EPC could be bad or what might cause it to read like that? thanks in advance

-- John