My partner's 2001 Mk1 1.4 16v AUB Fabia has been diagnosed by the RAC as having an open circuit to no.3 Injector so we're looking at an ECU problem  or wiring snag. I'm thinking wiring is more likely the issue but I'd like to be able to confirm the wire colours/pins for No 3 injector at the ECU in case they miraculously change colour en route from the injector rail! I've had no joy trying to source any relevent diagrams  and I've tried various places online, it all seems to be for later vehicles or the wrong model!! HELP  !! It was so much easier for the '92 volvo 940!!

Purple/yellow, pin 88 of ECU.

15 minutes ago, Wino said:

Purple/yellow, pin 88 of ECU.

 

Confirmed.

many thanks - I guess the other pin is straight to earth? Should be easy enough to check - kinda hoping its not the ecu!

No, the ECU switches the injector to earth so the other pin should be 12V.

Ahhh righto so constant 12v and a switched earth,cool - i think it may be the loom because changing HT leads seemed to 'cure' an 'EGR no ground' fault and its Eng management light as well as cure the misfiring for three weeks. Might have moved the loom a bit. Just in case I've been looking for a used loom and there's not much about.... 

The 'water box', the bit under the wipers, has drains at each end that go into the wheel arches. The holes are pretty big, so relatively unlikely to block.

However, at two places (one each side) on the way to those drains there are bunches of wires coming out vertically downwards into the engine bay. These have grommets around them that are designed to seal the orifices in the metalwork. All along the front edge of the water box, there's a foam rubber seal on the vertical metal panel at the front of the box.  Not sure whether it's the foam seal, or the grommets, or both, but after rain (or simulated rain) you may observe streams of water running down these wiring looms within the engine bay.  I suspect some of the wiring issues with this platform of cars is caused by this regular rinsing of the wiring. 

 

Here's a photo of my Polo, with one N/S drain hole (ringed in red) and one of the loom bunches that may suffer this 'unintended drain path' problem.

 

Have a look at yours with maybe some 'simulated rain' onto the windscreen,  then have a look at that wiring loom bunch under the ECU, see if there's any obvious carnage where water may have met cracked plastic insulation.

 

 

Edited 6 April, 20179 yr by Wino

cheers Wino will look into this too. finding time is the issue at the moment...