Have to admire your perseverance with this.  I'd have sold it and bought something else months ago.

On 7/30/2024 at 4:59 PM, Phantom76 said:

so after more investigations ive found that the wiring is intact as far back as the earth cable joins the harnes. so now im suspecting that the pcm is bad. is there anyway way to do a diagnostic check on it with forscan ? i have done key on and off test but after that im lost. 

question 2 if he pcm is bad what info do i need and when would be the best place to source 1 ? or is repair even worth it 

I have found this thread rather difficult to follow, so forgive me if I am not up to date.

The PCM can be tested using FORScan under the 'PCM Self-Test' function, although this will of course not conclusively exclude the PCM as the cause. From what I can recall of your issues, I don't think you have evidence pointing to a PCM fault, you have had no 'PCM processor fault' codes or the like.

You suspect a wiring fault and as far as I can tell, having already explained that you don't know much at all about wiring or electrics, you have done some basic continuity testing of a variety of wires - which hasn't allowed you to exclude the wiring harness as a cause of your problems. You have not been able to load test the wiring, nor can you test for faults which occur when the harness moves around etc, etc.

I remain confused as to why you do not just replace the engine bay wiring loom with a second-hand replacement for £100 or so. You are spending considerable time and effort trying to identify the specific precise point of your issue, and I don't think that is working out to be a pragmatic approach (unless you have unlimited time on your hands and the patience of a saint!). Despite all this testing, you still cannot confidently conclude that the wiring is fine, or that it isn't.

 

I believe that the most sensible next course of action would be to replace the loom. By doing this, at least you know you will be able to firmly park the 'wiring loom issue' idea one way or another. At worst, this will allow you to exclude the loom as the cause of your problems. At best, it will solve your problems.

 

Whether you then decide to conduct an autopsy of the loom or not is up to you 🤣

 

i would replace the harnes if only a second hand 1 could be found 
already did pcm self test all ok no faults found 
i have had 2 supposedly good auto electricians look at it can find no fault with the wiring back to pcm have done the same myself 
so the last port of call is the pcm not doing something with the earth when it wakes up  or is doing something with it that it shouldnt be

i just cant get my head around why the earth drops away when the pcm comes alive 

2 hours ago, ssmith93 said:

I have found this thread rather difficult to follow, so forgive me if I am not up to date.

The PCM can be tested using FORScan under the 'PCM Self-Test' function, although this will of course not conclusively exclude the PCM as the cause. From what I can recall of your issues, I don't think you have evidence pointing to a PCM fault, you have had no 'PCM processor fault' codes or the like.

You suspect a wiring fault and as far as I can tell, having already explained that you don't know much at all about wiring or electrics, you have done some basic continuity testing of a variety of wires - which hasn't allowed you to exclude the wiring harness as a cause of your problems. You have not been able to load test the wiring, nor can you test for faults which occur when the harness moves around etc, etc.

I remain confused as to why you do not just replace the engine bay wiring loom with a second-hand replacement for £100 or so. You are spending considerable time and effort trying to identify the specific precise point of your issue, and I don't think that is working out to be a pragmatic approach (unless you have unlimited time on your hands and the patience of a saint!). Despite all this testing, you still cannot confidently conclude that the wiring is fine, or that it isn't.

 

I believe that the most sensible next course of action would be to replace the loom. By doing this, at least you know you will be able to firmly park the 'wiring loom issue' idea one way or another. At worst, this will allow you to exclude the loom as the cause of your problems. At best, it will solve your problems.

 

Whether you then decide to conduct an autopsy of the loom or not is up to you 🤣

 

 

 

On 8/2/2024 at 3:59 PM, Phantom76 said:

i would replace the harnes if only a second hand 1 could be found 
already did pcm self test all ok no faults found 
i have had 2 supposedly good auto electricians look at it can find no fault with the wiring back to pcm have done the same myself 
so the last port of call is the pcm not doing something with the earth when it wakes up  or is doing something with it that it shouldnt be

i just cant get my head around why the earth drops away when the pcm comes alive 

 

 

What is the part number for your harness? It will be found on a label underneath the air box fixed to the small earth strap.

f1tf0-12a690 daj

think i might have found 1 on ebay waiting on reply to see if it will fit my car 

https://www.ebay.ie/itm/276444486115?_trkparms=amclksrc%3DITM%26aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20211130125621%26meid%3Dd47f419fce89430b9cf16e83aa7eed48%26pid%3D101465%26rk%3D1%26rkt%3D4%26mehot%3Dlo%26sd%3D276444486115%26itm%3D276444486115%26pmt%3D0%26noa%3D1%26pg%3D3650466%26brand%3DFord&_trksid=p3650466.c101465.m3507

It's worth giving ford parts a ring because they will be able to tell you the other looms which will fit your car (there will be other versions too.

update i managed to source the proper harness and plan is to change it out tomorrow. any advice on what to watch out for and if there is any special procedures ?? blike i cant see a reason but dos the harness need to be programmed to the pcm ?

 

TIA Phantom 

im determent  to get to the bottom of this 

Quote

i just cant get my head around why the earth drops away when the pcm comes alive 

 

why wouldn't the engine ECU go bad - they are getting old - heat, vibration, abuse, and of course designed in death with chocolate capacitors

and why would fitting a secondhand loom be a great idea ? what makes that one a known good one ?

I will be interested to see whether the replacement harness solves your issue. If nothing else it will help exclude it as the issue. @Botus I totally see your point about replacing the PCM which will presumably be his next step if the loom replacement doesn't work.

 

@Phantom76 I don't have your engine so I can't give you any specific advice on putting the new loom in. It really wasn't a bad job on my 2.0 diesel. I did check that the replacement harness had all identical connectors on before I started, as mine wasn't the exact same part number it was a newer one. If you have the identical part then I wouldn't worry about that.

• Make sure you disconnect the ground wire from the battery before you start.
• Take your time and be careful with the connectors as they can be fiddly to remove, often they need a tab pressing in with a screwdriver or a tab pulled out. If you can't see them easily or can't work out the mechanism then have a look at the ones on your new harness.
• I work from the PCM backwards around the engine, but there is no reason you couldn't do it the other way round.
• You will need some cable ties to deal with any broken retaining clips you encounter along the way.

Good luck and let us know how you get on.

 

13 hours ago, Botus said:

 

why wouldn't the engine ECU go bad - they are getting old - heat, vibration, abuse, and of course designed in death with chocolate capacitors

and why would fitting a secondhand loom be a great idea ? what makes that one a known good one ?

i appreciate your comment but why would it be worth my while forking out hundreds of euros for a loom that i dont even know is the issue. if not the issue i have no problem moving the loom on and then using the funds from that to fund the pcm replacement chasing parts with new parts is a very expensive way to go. i was told by an old mechanic to stop thinking like a technician and more like a mechanic a computer wont tell you everything, you need to use your head 

1 hour ago, ssmith93 said:

I will be interested to see whether the replacement harness solves your issue. If nothing else it will help exclude it as the issue. @Botus I totally see your point about replacing the PCM which will presumably be his next step if the loom replacement doesn't work.

 

@Phantom76 I don't have your engine so I can't give you any specific advice on putting the new loom in. It really wasn't a bad job on my 2.0 diesel. I did check that the replacement harness had all identical connectors on before I started, as mine wasn't the exact same part number it was a newer one. If you have the identical part then I wouldn't worry about that.

• Make sure you disconnect the ground wire from the battery before you start.
• Take your time and be careful with the connectors as they can be fiddly to remove, often they need a tab pressing in with a screwdriver or a tab pulled out. If you can't see them easily or can't work out the mechanism then have a look at the ones on your new harness.
• I work from the PCM backwards around the engine, but there is no reason you couldn't do it the other way round.
• You will need some cable ties to deal with any broken retaining clips you encounter along the way.

Good luck and let us know how you get on.

 

the cable ties wont be needed thank god it looks like every retaining clip seems to be on the loom and in tack im shocked they took the time to remove each 1. i was expecting to see the loom ripped out and id have to tape it back together lol. it dose look like going from the pcm is the right move my fear of that is the tamper box and braking the studs. i know its gonna happen and drilling is the only option. ill be starting it this evening and ill finish it tomorrow morning but ill be surprised if its the loom im still hell bent on the pcm beginning to die. ill post the update and if not difficult i might do a how to post with photos as i go 

How did you get on this evening?

Any update to this, how did your harness replacement go? 

im actually in the middle of it right now. pcm looks as it was rooted at before the tamper bolts are all sheered off already and the top of the housing was pulled open as if someone was having a look. its not a bad job so far just getting some of the block connections apart is a pain in the hole

if nothing else its finally out. next question is how hard is it to source a taper proof box for it ? ive tried drilling but i know in my hart im gonna butcher it lol

 

How did you get on with your harness replacement? Did it make any difference to your problems?

@Phantom76 hasn't been on since Aug 21st. I wonder if that means that he got fed up with trying to sort out the issue and gave up, or if he has fixed it!

I also have this problem with a P02E4 and a P02EC

It's intermittent but looking at live data it doesn't always appear to operate, the TB-THROTTLE BODY, and it sets no codes, then when it does operate like i think it should it doesn't stay working like that for long. 

I'm a HGV master tech but not an electrician but know what I'm looking at, all my wires check out on my scope, the only thing i can think is that the pcm is pulsing the motor wires incorrectly this not getting your live and earth at the right time to operate the motor, I'd rather prove this before going through the hassle of a new pcm.....all I've tested it with is the uscope 1 channel, really need a 2 at the least... Anyway i wish that phantom guy had come back with an answer.... I'll definitely let people know my fix because it seems to be quite a common problem with no answer, unless you do have something that is clearly broken.... I have all the signals i would expect from initial diagnosis

So I hooked up a scope today.

yellow is pin 1 of the throttle motor,

turquoise pin 2 of the motor,

purple sensor ground

green sensor signal

So the yellow pwm signal seems to happen when the throttle body isn't being commanded, as i can see this from scanner data, the 0.5v green is the throttle body in its normally wide open position.

When the throttle body is commanded, the yellow goes to battery voltage and the turquoise is pulsed to ground........see in the picture the green tries to move a little.......does anyone know what this picture might mean? as in the yellow and turquoise moving together? are they shorted in the ecu maybe?

Ive tested all wires with headlight bulb and operated the actual throttle motor from the ecu end with a power probe (ecu disconnected) all works fine. Operating the throttle valve by hand the voltages change in the scan data and unplugging it brings the voltage to 5v as i would expect.

Having not seen a working throttle body being pulsed on a scope i dont know if im missing something obvious.

When i was at idle the other day it did appear to start working as i would expect.....throttle flap almost closed, voltage on the sensor to 4v and adjusted accordingly as i revved the engine....could there be another sensor stopping this from working.....both my APPs look good

oh i have tried 2x throttle bodys, both motors ohm out approx 3.5ohms

SOLVED, see attached link to diagnosis and info