Ford Fiesta ST
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#563324 - 08/09/19 03:27 PM Electrical gremlin - Help Please!
RallyMatt Offline

Registered: 08/09/19
Posts: 2
Hi All,

Am hoping someone may be able to help or have had a similar issue?

Was on my way to work after a full engine rebuild from the main shells up as the car had run fine for a few days. I did the TB reset on restart and had done the half hour on tick over and a short drive the day before. When close to work traffic all suddenly stopped in front of me resulting in the ST150 stalling so bumped it while I still had some momentum. A short while later the dash lights all went scatty, Rev counter worked, speedo didnít, EML came on, as did ABS, PATS, Battery, Brake, fuel gauge stayed as should be yet temp gauge was flashing. Managed to get to work when the car would then not restart, just flash the lights at me.

I plugged the OBD2 reader in and it came up with error codes U1900 and U0073 which both cleared... car still wouldnít start. Fuel pump kicks in for a fraction of a second but not as long as normal and the immobiliser light flashes away. So, with a few tools I double checked earths, made sure the wiring had not been rubbing and triple check connections. Not sure what I had done but it restarted so I braved the journey home. On the return journey everything was fine for a few minutes except the immobiliser light which was still flashing, afterwards the whole dash went mental again and I even had the EAC Fail yet the car was driving all ok. After having it cut out another two times I gave up and called recovery.

After some research I swapped the dial cluster over for two other spares we have in the shed and had the exact same issue with those so itís not that. Battery is sat at a nice 12.8v after a night off the car and this is not the usual flat battery like Ďclickí.

Today I have gone over the whole of the loom which was taken out or messed with during the rebuild, everything is where it should be and even taking off the plastic isolation covers reveals nothing untoward. All fuses have been checked including the box in the engine bay attached to the battery tray and are all fine yet I still have the same intermittent non start issue which now has become a constant instead.

Just wondering if anyone had experienced anything similar to this or had any ideas where to look at next as Iím running out! Itís really frustrating as the engine sounds sweet without the bottom end knock, just a shame I canít start it anymore! Lol!

#563333 - 09/09/19 02:22 PM Re: Electrical gremlin - Help Please! [Re: RallyMatt]
_Jimmy_ Online   happy
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Registered: 11/02/14
Posts: 1280
Loc: Northwest
Just a thought, I have heard of people having gremlins due to the earth cable connection under the battery tray getting badly corroded.
2005 Fiesta ST
Milltek non-res, Newman fast road cams, Fusion Fabs custom inlet manifold

#563338 - 10/09/19 11:38 AM Re: Electrical gremlin - Help Please! [Re: RallyMatt]
RallyMatt Offline

Registered: 08/09/19
Posts: 2
Thanks Jimmy. That was one of my first thoughts too but when going through all the parts of the loom I had disturbed when rebuilding the engine I went through and cleaned up all the earths with no joy.

Have just spoken to an auto electrician who says that the 5amp EM fuse is well known within the trade to corrode which in turn stops the can-bus communication and can give similar results to what I am experiencing with no PCM communication. Apparently for peoples future reference the ABS controller may also cause this fault so I will be doing further investigations over the next few evenings and see if either of these resolve the issue.

Once I know for sure I will post on here in case anyone has a similar fault in the future. 👍🏻


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