Pas and maf issue

[Thisday]

sorry as soon as i posted i figured it out - you pull down from the top. right ive tested where it come from the bulkhead - power and where the loom goes down as per your post No. 59 first picture - no power - so the problem is somewhere between them.

 

so my option are ( assume) keep searching to find the break - or run a piece of wire from the bulkhead to the testing point near the loom?

[Thisday]

 

this is the one showing no voltage

[Thisday]

I've also just noticed there also appears to be a yellow on black wire on the right hand set of connectors (see pic), although I cant see another one of these in the loom further down (as per the pic above) - the left one is the one I tested based on your pics Wino(has power).

 

Edited 12 March, 2016 by Thisday

[Breezy_Pete]

There may be other same-colour wires doing different things, it's the wire with the black tape around in your above photo that you need to focus on getting to the MAF/PAS and anything else it used to get to, I reckon. Is it coming through a blue rubber seal like in mine? And in the same position? Wanna make sure you've definitely got the right wire.

Did you put that tape there? It looks almost like that wire finishes inside that bit of tape, but I guess that's just the photo.

Edited 12 March, 2016 by Wino

[Thisday]

There may be other same-colour wires doing different things, it's the wire with the black tape around in your above photo that you need to focus on getting to the MAF/PAS and anything else it used to get to, I reckon.

Did you put that tape there? It looks almost like that wire finishes inside that bit of tape, but I guess that's just the photo.

Ah I put the tape there, nothing on the loom looks like its been touched previously.

So you recon I need to undo the rest of the loom and trace it and it's voltage all the way down?

Edited 12 March, 2016 by Thisday

[Thisday]

Yep, it comes through a blue seal

[Breezy_Pete]

Ah I put the tape there, nothing on the loom looks like its been touched previously.

So you recon I need to undo the rest of the loom and trace it and it's voltage all the way down?

I see.

Well it would be nice to find the spot where the wire is busted, just in case there's any damage to any others in the same spot, now that you're in there.

[Thisday]

I see.

Well it would be nice to find the spot where the wire is busted, just in case there's any damage to any others in the same spot, now that you're in there.

OK, shall attack this Tomoz now as Mrs off to work soon. I must say I am not looking forward to it!

Any suggestions for the best way to cover where I have broken the insulation? I used gaffer tape but not a fan really, was thinking maybe a dab of silicone sealant.

Also, when miracles happen and I need to recover the loom, is electrical tape best or would gaffer tape do just a good of job? I ask mainly cause gaffer tape is much wider and therefore quicker! Haha

Edited 12 March, 2016 by Thisday

[Breezy_Pete]

I don't think I'd advise silicone sealant because most types give off a little vinegar as they cure, which will attack the copper of the wire I should think.  I'd just bind up any areas where the insulation has been compromised with electrical tape.

I reckon if it was me, I'd try to very carefully slit the existing taping lengthways along the top of the loom bunch (small pair of blunt-tipped scissors?), tease out the wire you're interested in, then when you're finished and everything's sorted, just run a length of insulation tape lengthways along to 'zip up' your slitting, then pop a few tyraps round to hold it all together?

 

Hope it goes well for you tomorrow.

[Thisday]

Well opened up the whole loom. Seems I had the wrong wore yesterday and there was power on ignition.

So its looking to be beyond my allowance of skill or time and I think it's time to take it to someone with experience.

Thanks for all of your help Wino, I might not have solved the problem but I have learnt things along the way!

[[Cas]]

I wanted to show my appreciation for the contributions of Thisday and Wino to this thread as I am facing the exact same issue of PAS dead with simultaneous MAF fault. The details here have helped tremedously in tracking down the problem. I may write up a guide but for now I shall just post the results of my fault finding.

 

I followed most of the steps for tracing the fault, fuses were fine but no 12 volts on MAF pin 2 with ignition on. I removed the scuttle panel and wiper motor to expose parition connectors. Note both plugs can be disconnected by undoing the T35 screw so easier to test between interior fuses and the black/yellow PAS wire (i'll check the pin number tomorrow).

 

 

After finding no issues with the loom from the interior and along the scuttle panel, the only place left was between the loom dropping into the engine bay and the MAF and PAS connectors. I found that the MAF and PAS wires are joined with the black/yellow wire from the fuse box and an engine wire in a flexible conduit located just behind the battery so this is another place to check and use at a reference point (I'll add a photo).

 

All this sleuthing led me to investigate the exposed loom behind the ABS pump where I finally found the problem!

 

 

The above photos show that the exposed loom wires have been rubbing on the corner of the ABS pump and with water seeping down this section of loom making things worse. In the center of the last photo is the black/yellow PAS wire that has broken along with 4 or 5 more others. Splicing in new wires is going to be annoying but I am so glad I have found the issue and it is fixable. I hope this helps anyone else with weird electrical issues as this seems to be a very fragile section of the loom.

[Breezy_Pete]

Great work tracking that down!

I only just recently myself discovered that the engine bay loom(s) can disconnect/unplug at the bulkhead with that/those Torx screws (only one takes all the loom except the main terminal 30 feed through on our car, the other just takes the terminal 30 feed through, some pics here: https://www.briskoda.net/forums/topic/446560-fabia-electrically-died-whilst-driving/).

That grommet surrounding the descending loom in your first picture is - I think - meant to prevent water running down in/around the loom into the engine bay, and the steel panel on the front of the scuttle has a crappy foam seal (like door carriers) which is probably also supposed to stop water finding it's way out of the scuttle/waterbox from anywhere except the end drains. It doesn't really work.

 

I guess if the loom hadn't rubbed on your ABS module, water wouldn't have been able to attack the copper, but I'd advise people to clear the scuttle drains, seal these grommets etc with Plumbers Gold and inspect this 'rubbing on the ABS module' possibility if they value their car's long-term future.

 

Guess I'll be peering down the back of the engine bay in the morning with a strong torch.

thanks for posting.

 

Edited 17 August, 2018 by Wino

[LB123]

Excellent 'find'. Excellent third post. Confirms the MAF/PAS fault association but also possibly implicated in all sorts of engine bay electrical odities by highlighting another loom weak point. I will be peering down there tomorrow also.

Edited 17 August, 2018 by LB123

[TMB]

11 minutes ago, LB123 said:

I will be peering down there tomorrow also.

 

Me too!

[TMB]

I had to take the air filter box off mine to be able to inspect the loom properly. Also had to unclip the ECU and move it slightly forward, but that is very easy.

 

The loom was fine where it goes behind the ABS unit, with a reasonable gap between it and the loom. However I did notice further down that the loom looked ready to start rubbing on the sharp edge of the chassis rail. The wires aren't even covered by much tape but they were undamaged, thankfully.

I slit a piece of rubber hose and pushed it onto the chassis rail to prevent any chance of it rubbing in future. Also saw three earth wires down there which I took the opportunity to remove, clean and apply some petroleum jelly to. To be fair they were surprisingly clean anyway.

 

 

 

 

 

 

 

 

 

 

 

 

Edited 18 August, 2018 by TMB