Fried ECU? Please help
Lead Driver
Joined: Aug 2006
Posts: 5,670
Likes: 12
From: Sand Lake, MI
When I say
"see the sensors that take effect once it goes closed loop, one, or more or them should be your problem."
I mean it could be a sensor or it could be the wiring itself to a sensor. A sensor could be back feeding the computer voltage via a short in it. And no I not sure one could do that.
Electrical problems can be a pain to figure out, the fact you had a computer go up in smoke is the part I'd be very leery of. I wouldn't tend to be very happy or content about it until I found out why that happen.
"see the sensors that take effect once it goes closed loop, one, or more or them should be your problem."
I mean it could be a sensor or it could be the wiring itself to a sensor. A sensor could be back feeding the computer voltage via a short in it. And no I not sure one could do that.
Electrical problems can be a pain to figure out, the fact you had a computer go up in smoke is the part I'd be very leery of. I wouldn't tend to be very happy or content about it until I found out why that happen.
Thread Starter
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Senior User
Joined: May 2008
Posts: 374
Likes: 1
Sorry, my bad. I meant I have a code 122 not 112. But I had it before replacing the tps and after.
How in the world would I begin to check wiring to every sensor. Surely there are some short cuts and tricks. I can not imagine trying to find a nick in a wire that is concealed in a bundle running the length of the truck! I would rather just cut out all the old and replace with new wiring. I believe that would be much quicker.
What is funny is I am an electrician but I absolutely hate troubeshooting electrical problems on vehicles.
How in the world would I begin to check wiring to every sensor. Surely there are some short cuts and tricks. I can not imagine trying to find a nick in a wire that is concealed in a bundle running the length of the truck! I would rather just cut out all the old and replace with new wiring. I believe that would be much quicker.
What is funny is I am an electrician but I absolutely hate troubeshooting electrical problems on vehicles.
Lead Driver
Joined: Aug 2006
Posts: 5,670
Likes: 12
From: Sand Lake, MI
No not a nick, I tend to think a burnt spot of some kind, two wires melted together, something like that could be very easily overlooked.
A nicked wire would only tend to be a problem when wet and more then one wire has damaged casing near each other.
While one single wire with a small nick may corrode over time from it out from the nicked point, it would not cause a computer to go up in smoke.......at least we'd hope not! lol
If you don't find one, you don't find one. Like I said, myself I'd be happier if I did, at least then I could fix it and feel better about the whole deal with the computer frying.
Then move on to any other issues that remain if that repair didn't correct them all, may be left with a dead sensor that went when the computer did.
All you can do is look.
It's all going bad once its gotten up to running temp shows it has something to do with the sensors in use once it gets to that point.
Or the computer itself is bad.
Funny how it always comes back to that huh? lol!
A nicked wire would only tend to be a problem when wet and more then one wire has damaged casing near each other.
While one single wire with a small nick may corrode over time from it out from the nicked point, it would not cause a computer to go up in smoke.......at least we'd hope not! lol
If you don't find one, you don't find one. Like I said, myself I'd be happier if I did, at least then I could fix it and feel better about the whole deal with the computer frying.
Then move on to any other issues that remain if that repair didn't correct them all, may be left with a dead sensor that went when the computer did.
All you can do is look.
It's all going bad once its gotten up to running temp shows it has something to do with the sensors in use once it gets to that point.
Or the computer itself is bad.
Funny how it always comes back to that huh? lol!
Thread Starter
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Senior User
Joined: May 2008
Posts: 374
Likes: 1
I totally agree with you. I want to find what happened to begin with. I woke up with a thought this morning. If I have a bad wire from the tps to the computer, that would explain the 122 code and the fact that it runs fine when it is cold (since the tps is not used until warmed up, I think?). I am going to look around the engine wiring today after work. Any thoughts?
Post Fiend
Joined: May 2004
Posts: 11,289
Likes: 6
From: Lakewood, Ohio
sounds like a good idea on the wiring.
i would suggest to get away from the truck for a while today and watch some olympics or something else.
then come back fresh for another look.
good luck today.
i would suggest to get away from the truck for a while today and watch some olympics or something else.
then come back fresh for another look.
good luck today.
Posting Guru
Joined: May 2007
Posts: 1,208
Likes: 2
From: North Reading Mass
On the full size Bronco site there was a reference to a TSB that concerned the wiring that feeds the ignition module. This is very near the ECU harness where it plugs in. I would check this area for water damage and corrosion. ECUs burning up is rare, bad grounds are common. Make sure the alternator voltage is stable. good luck
regards
rikard
regards
rikard
Lead Driver
Joined: Nov 2002
Posts: 9,555
Likes: 40
From: Concord, NC
It runs open loop until it gets up to running temp, then goes closed loop and the computer takes over.
Like others have suggested, I think that the problem is in the wiring somewhere. This is the second computer that you have had problems with, and this one ran fine for a while before it went to running like it did before replacing the computer, correct? Whatever it is that is causing the problem needs to be fixed, or every new computer you put in the truck will fail the same as these. This seems likely to me since you have the hard fault code.
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Lead Driver
Joined: Aug 2006
Posts: 5,670
Likes: 12
From: Sand Lake, MI
<>The computer is always in control of the engine. Open loop simply means that the computer is not using the real-time O2 sensor feedback for mixture control.</i>
Sorry, I was being to general I guess, wording was wrong but I think the OP gets the point I was trying to make.
Yes the computer is always in control, some sensors are ignored what have ya during warm up and cold drive away conditions that come into play once up to full temp.
The chart that subford posted, the same chart I linked to earlier shows the OP what sensors and wiring to look to for the possible cause of the problem/s once up to temp.
Sorry, I was being to general I guess, wording was wrong but I think the OP gets the point I was trying to make.
Yes the computer is always in control, some sensors are ignored what have ya during warm up and cold drive away conditions that come into play once up to full temp.
The chart that subford posted, the same chart I linked to earlier shows the OP what sensors and wiring to look to for the possible cause of the problem/s once up to temp.
Fleet Owner
Joined: Aug 2005
Posts: 23,666
Likes: 301
From: Easton,Ks
Lead Driver
Joined: Nov 2002
Posts: 9,555
Likes: 40
From: Concord, NC
That chart and strategies link are good references, but they shouldn't be regarded as absolute truths, as there are a few things that are not correct. They will get you in the right direction, though.
Thread Starter
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Senior User
Joined: May 2008
Posts: 374
Likes: 1
Well, I did not find anything like I was hoping around the tps. I have looked over the wiring harness under the hood and did not find anything wrong. I even took loose the eec connector, and the other two connectors on the firewall and pulled all the wiring up so I could get a better look in between the wires. The only place I have not inspected the actual wires is under the upper intake. But I did take a small mirror and flashlight to look over the taped harness. If I don't find anything anywhere else, then I will pull the upper intake and take loose the harness.
I am going to go look now under the truck around the tranny wiring.
Wish me luck! lol
I am going to go look now under the truck around the tranny wiring.
Wish me luck! lol
Lead Driver
Joined: Aug 2006
Posts: 5,670
Likes: 12
From: Sand Lake, MI
Good luck!
I hope you find something, anything that could have/would have fried that computer so you can fix it so it won't happen again and be done with it.
Be sure and let us know how you make out.
One test you could try is find out what pins should not have continuity to ground from the EEC connector and test them to see if they do. If you found one that does, that would likely be the problem?
I'd have to review the wiring diagram to verify that type of test would show anything but I think you get the idea of what I'm getting at.
That way you limit your search/work area to one spot, testing each pin right at the connector. Rather than crawling all over and under the truck tearing into the harness.
I hope you find something, anything that could have/would have fried that computer so you can fix it so it won't happen again and be done with it.
Be sure and let us know how you make out.
One test you could try is find out what pins should not have continuity to ground from the EEC connector and test them to see if they do. If you found one that does, that would likely be the problem?
I'd have to review the wiring diagram to verify that type of test would show anything but I think you get the idea of what I'm getting at.
That way you limit your search/work area to one spot, testing each pin right at the connector. Rather than crawling all over and under the truck tearing into the harness.
Thread Starter
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Senior User
Joined: May 2008
Posts: 374
Likes: 1
Thanks danr1, I will start trying that. I have crawled under the truck as well and have found nothing. I put the negative cable back on and ran the codes without warming up the engine. All I got was 122 again, and 512 (keep alive memory test failure). That 122 code (tps voltage too low) just keeps bugging me why it would be there if there was not a problem with it or the computer or wiring in between.