Miks15
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| posted on 11/2/13 at 05:42 PM |
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MK5 Fiesta ECU help
Hey Guys,
Ive been having some problems with my fiesta. I apologise now for the long description but probably best to give as much detail as possible.
Just over a week a go I got in my car and it started as normal, then a couple seconds later as I began to pull away it died. I went to start it again
and the starter wouldn't even kick in.
I had a multimeter on the starter checking all the connections and traced it back to the starter relay. It seemed there wasn't an earth. I found
a wiring diagram and it seems what i thought was just an earth, went back to the ECU. I could short the relay and crank the engine, but obviously
there was no spark. So i think we have an ECU problem.
The little red light goes out on the dash when the key is put in the igniton so i dont think its an immobiliser problem. A few of the dash lights come
on when the key is first turned, and the lights dim and radio turns off etc when i fully turn the key to try start it.
Has anyone got any ideas? Ive located the ECU but cant see any way to remove it, anyone happen to know how to take it out?
Any advice would be greatly appreciated.
Thanks
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theprisioner
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| posted on 11/2/13 at 07:00 PM |
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possible duff battery high internal resistance. Check volts across battery when starter is operated. If below 10V=duff
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big_wasa
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| posted on 11/2/13 at 07:04 PM |
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So fith gen' would be 2002>
So you get in the car and the red led in the clock flashes every 2 sec' or so ?
You turn the ignition key to run and the fuel pump primes for about 2 sec and the red led stays on solid for about three sec' It then goes out
all together ?
You then crank the engine over. Does the led flash at all ?
The starter relay is indeed controled by the ecu as part of the immobilizer (switched earth).
The fuel pump will prime when the ignition is turned to run even if there is a problem with the immobilizer but the fuel pump will no longer run if
the engine knows the engine is not turning over. ie the ecu also switches the earth on the fuel pump relay.
A crank or cam position sensor can do strange things.
Have you plugged it into an obd2 reader ? Any codes stored ?
If not I would look for bad earths and try another battery.
I dont get to butcher ecu's that new but they have an anti tamper cage over the ecu plug (two rivets on older models). What do you hope to
achieve my removing it ? Unless its wet ?
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bi22le
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| posted on 11/2/13 at 07:37 PM |
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red key means key programming i think. have yoy tried searching on Google?
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Miks15
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| posted on 11/2/13 at 09:50 PM |
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Hey guys thanks for the replies.
theprisoner, i will check this in the morning.
bigwasa,
I have tried an obd2 reader and it wont connect (we have had it connected before no problem). It says linking error which again is leading me to
believe an ecu fault. I dont necessarily want to remove the ecu just yet but would like to be able to see the numbers on it so I can get a replacement
if this is the problem. I would just like to try eliminate everything else.
Mk5 is 96-02 i believe, my car is the 02, one of the latest versions with the 1.25 zetec se.
The light on dash doesnt come on solid when the key is first put in and turned, it just stops flashing all together.
bi22le, i have a few spare keys and none work so I dont think its the key programming. I have tried to search for people with similar problems but
not to much avail so far.
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big_wasa
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| posted on 11/2/13 at 10:09 PM |
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I think you have some kind of power/earth fault.
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britishtrident
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| posted on 11/2/13 at 10:39 PM |
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Don't start pulling everything apart
You should first check the main engine earth connections and the ecu earth.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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Miks15
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| posted on 12/2/13 at 12:16 PM |
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I have checked the engine earth and will now check the ECU earth.
Ive checked all the fuses I can see relating to the ECU system and all seem to be fine. The problem really is that the ECU seems to be buried up
underneath the dash in the passengers footwell so its not particularly easy to get at the connections. If i could get to the connector I could check
all the power and earth connections and rule them out.
Anyone know if you can get at this without removing the dash?
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big_wasa
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| posted on 12/2/13 at 02:43 PM |
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The ecu has five earths. Four through the loom and a seperate one near the plug.
It has one permanent live (kam) and two switched lives. From your description you seem to be getting a voltage drop when cranking. Causing the
immobilizer to reset.
The alarm is a black box and is seperate from the ecu but still sees the signal from the pats.
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