Pas and maf issue

[Breezy_Pete]

Tried them all now, others showing 0.01/2v only the one showing exactly 5v with both ignition on/car running (used the strut bolt as the earth for info)

Is there a missing terminal at one end, so only 4 out 5 contacts used in the loom connector? If so, pin 2 is the next one in from that end (i.e. pin 1 isn't used).

I have a feeling you've just found that one to not have its 12V ignition live feed, and the one you've measured at 5V is pin 4, going to the ECU.  Need to trace that black/yellow wire back towards the cabin and find the break, if I'm right.

[Thisday]

Is there a missing terminal at one end, so only 4 out 5 contacts used in the loom connector? If so, pin 2 is the next one in from that end (i.e. pin 1 isn't used).

I have a feeling you've just found that one to not have its 12V ignition live feed, and the one you've measured at 5V is pin 4, going to the ECU. Need to trace that black/yellow wire back towards the cabin and find the break, if I'm right.

Thanks, you are right, there are 5 spaces, but only 4 in use the one next to the space was showing 0.02v, the others were 0.01v.

Was gonna steal my mates maf, to confirm as he has a pd100 polo, so can double check his set up and get him to test my maf too.

But sounds like I'm gonna end up under the car confused, lol. Thank for the advice, will report back any new findings!

[Breezy_Pete]

Is the MAF wiring near the aux belt?  I seem to remember a workmate (with a PD100 Octy) having trouble with his and he thought it had rubbed on the belt and got damaged that way, but that might have been MAP, not MAF, can't remember.

[Thisday]

Prob the map you are thinking of there, maf is on top right of engine bay, map bottom left near a/c condenser ect

[hutchysrs50]

So is this looking like a wire or the pump has failed?

ie its shorted a wire out in the pump or on the loom which has made the pump fail and blown the fuse.

[Breezy_Pete]

If there was a problem with either PAS module or MAF I would have expected the fuse to have re-blown by now. I reckon busted wire somewhere in engine bay, or a connection somewhere that's maybe got wet?

[dm222]

You can check the voltage of terminal 15 (one of the smaller wires that goes to ignition) with vcds (004.04).

 

If there is a problem at one of the other two smaller wires that would cause an error because they are synconized, when one raises voltage the other drops, the value is the difference between the two... when one of them is out of the params then the diference between the two is different than the expected causing an error.

 

The big wires, you can check also with vcds parameter 001.1. If the problem is in the bigger wires you can order new wires and replace them: 6Y0998010 wires + connector 1K0971955.

Edited 28 February, 2016 by dm222

[Thisday]

Is there a missing terminal at one end, so only 4 out 5 contacts used in the loom connector? If so, pin 2 is the next one in from that end (i.e. pin 1 isn't used).

I have a feeling you've just found that one to not have its 12V ignition live feed, and the one you've measured at 5V is pin 4, going to the ECU.  Need to trace that black/yellow wire back towards the cabin and find the break, if I'm right.

You as always were exactly right! pin 2 was next to the 'missing pin' i tested this on my mates PD100, his was showing 12v on his, mine had increased slightly to 0.2v (from 0.02)

 

Attempted to traced the wire back but was scuppered straight away as the MAF wires went straight into a massive loom at the firewall, see pic below (red dots - MAF, Blue - huge loom)

 

 

 

I also saw the same black / yellow wiring go into a plug behind the battery (as in pic below) - voltage on this wire was also showing 0.2V.

 

 

 

So to me its looking like the problem is probably in the loom behind the dash, I was gonna pull the radio out an see if anything jumps out at me. but other than that i'm lost for ideas and its looking like it might end up going to auto-electrician - unless anyone can suggest anything else/an easy way to locate/test the ignition wire.

 

Seen the last post re VCDS - not sure how to scan voltage codes etc

[Breezy_Pete]

Hmm, where that great big bunch of wires comes down out of the 'water box' is a bit of a leak path where water comes down through the hole that the loom comes through, I wonder if that drippage has got into a wire somewhere round there. There's a big rectangular grommet that's meant to stop water coming down there, but it doesn't seem to work that well. You can test it by pouring water straight into the area under the wipers and see where it comes out, don't overdo the amount in case your drains are blocked and it ends up going somewhere like the cabin air intake.

 

Here's a pic of the general area on my Polo, with the 'proper' drain hole ringed in red, and the leak paths past the grommet marked in blue:

 

 

I wonder if you could pick up the black/yellow wire somewhere back towards the cabin and bypass that area after checking that the 12V is there at the point you pick.  Where it comes through from the cabin is over on the driver's side under/behind the wiper motor/mechanism:

 

There's a couple of these boxes (black arrow) side by side, and another drip path associated with another loom branch going down through the bottom of the panel below the black arrow;

 

[Thisday]

Cheers,

 

Will do the water test later - pretty sure that drain is free, as checked looked at it when I had the arch liner off (if thats the same one) - would it be worth measuring the voltage at fuse 7? to confirm the 12v is getting there in the first place?

 

To check the loom elsewhere am I looking at removing the scuttle panel?

[Breezy_Pete]

Yep, definitely check that you have 12v on both sides of fuse 7 when ignition is on (probing through the top of the fuse).  Yeah, my pics are with the black plastic cover removed off the top of that area, and the metal 'front' cover that comes up vertical-ish. It's slightly different on the Polo, but in the detail rather than fundamentally.  I think this is the wire where it comes through from the cabin, Pin 1 of connector K (T11b) There's an unpluggable connector on the inside of the firewall that you could check is getting the 12V, but access will be hard, I think.

 

 

That's the left hand of the two sets of connectors, the right one shown with cover on in previous post.

Edited 29 February, 2016 by Wino

[Thisday]

Sorry by checking both sides do you mean , red wire on multimeter to one side of fuse then the other to earth?

 

Not sure if the fuses i have allow for testing while the fuse is in place...? - i might be wrong, never really studied them

 

right- looks as though I need a wiper puller!

[Breezy_Pete]

Can you not probe the mini-blade fuses (top few rows in fusebox) when they're fitted? A photo I've just looked at has some little squares of metal either side of where the fuse value is written? May be covered by plastic, not sure. If you can't, just check with it out that with ignition on there's 12V on one of the connections that fuse 7 plugs into, (with other probe on an earth, yes).

 

[Thisday]

Can you not probe the mini-blade fuses (top few rows in fusebox) when they're fitted? A photo I've just looked at has some little squares of metal either side of where the fuse value is written? May be covered by plastic, not sure. If you can't, just check with it out that with ignition on there's 12V on one of the connections that fuse 7 plugs into, (with other probe on an earth, yes).

You were right yet again! The fuses did have the little contacts at the end-never noticed em before.

Getting 12v if both pins so next step is scuttle panel off I'm guessing?

Edited 29 February, 2016 by Thisday

[Thisday]

Hmm, where that great big bunch of wires comes down out of the 'water box' is a bit of a leak path where water comes down through the hole that the loom comes through, I wonder if that drippage has got into a wire somewhere round there. There's a big rectangular grommet that's meant to stop water coming down there, but it doesn't seem to work that well. You can test it by pouring water straight into the area under the wipers and see where it comes out, don't overdo the amount in case your drains are blocked and it ends up going somewhere like the cabin air intake.

 

Here's a pic of the general area on my Polo, with the 'proper' drain hole ringed in red, and the leak paths past the grommet marked in blue:

 

 

I wonder if you could pick up the black/yellow wire somewhere back towards the cabin and bypass that area after checking that the 12V is there at the point you pick.  Where it comes through from the cabin is over on the driver's side under/behind the wiper motor/mechanism:

 

There's a couple of these boxes (black arrow) side by side, and another drip path associated with another loom branch going down through the bottom of the panel below the black arrow;

 

 

Well once again you are correct - the wires in the pic below were somewhat soaked this morning following the rain we've had.

 

 

In addition - the rain has performed a miracle and made the PAS work again (light also gone off) and the although the MAF light is still there - performance is back - although does sometimes go then come back. So i think we can confirm the issue is wiring related. One note - it all started working after driving for 5mins in the rain.

 

on a related but annoying note - tried to get a better look at the water ingress and managed to break one of the clips holding the ECU in place...grrr!

[Breezy_Pete]

One approach - to confirm diagnosis or longer term - would be to cut the blue/black wire (the after-fuse colour up to the firewall connector) somewhere behind fuse 7 and join a longish length of thickish (1.5mm² or more) wire to the part going to the fuse. Then run that across under the dash to the grommet where people often take a power feed through for an amplifier or whatever, the one that would take the bonnet release cable through on a LHD car. (See Tech1es thread about his saloon for nice piccies)

 

Then, somewhere near the battery (?) in the engine bay, I think there's a 14-pin connector that the black/yellow wire from the firewall connector goes to. Not sure if that's where the split occurs for the wires going to MAF and PAS (one wire going into one side of the connector at pin 11, two coming out of the mating pin 11?) Speculation but worth a look if you can find that connector pair. That would be a nice place to run the new wire into if you can find it.  Then you'd have isolated both ends of the wire giving trouble.

 

Sounds pretty cowboyish, but might be quite easy compared to getting into the scuttle and dealing with big loom bunches? Should be safe enough because your new wire is fused at the fusebox.

 

I'll do a little sketch of what I mean for clarity, in a minute.

 

Here you go:

 

Edited 1 March, 2016 by Wino

[Thisday]

One approach - to confirm diagnosis or longer term - would be to cut the blue/black wire (the after-fuse colour up to the firewall connector) somewhere behind fuse 7 and join a longish length of thickish (1.5mm² or more) wire to the part going to the fuse. Then run that across under the dash to the grommet where people often take a power feed through for an amplifier or whatever, the one that would take the bonnet release cable through on a LHD car. (See Tech1es thread about his saloon for nice piccies)

 

Then, somewhere near the battery (?) in the engine bay, I think there's a 14-pin connector that the black/yellow wire from the firewall connector goes to. Not sure if that's where the split occurs for the wires going to MAF and PAS (one wire going into one side of the connector at pin 11, two coming out of the mating pin 11?) Speculation but worth a look if you can find that connector pair. That would be a nice place to run the new wire into if you can find it.  Then you'd have isolated both ends of the wire giving trouble.

 

Sounds pretty cowboyish, but might be quite easy compared to getting into the scuttle and dealing with big loom bunches? Should be safe enough because your new wire is fused at the fusebox.

 

I'll do a little sketch of what I mean for clarity, in a minute.

 

Here you go:

 

 

Thats great thanks, i was thinking that that could be a solution. However, i am not sure of the location of the 14way comm pair? T14a, in your pic? This sounds like the connector in my pic above - the one behind the battery??

[Breezy_Pete]

Do you mean the second photo in post#58? Is that 14 way? (Just checked on my Polo, yeah that looks like T14a).

And does pin 11 of that just go to the PAS , not the MAF then, is that what you're saying?  If so, you could just take your new wire to there and also branch off to the MAF from the same point, cutting the original MAF feed?

On the Polo pin 11 looks to be second from top in front column. 

[Thisday]

Do you mean the second photo in post#58? Is that 14 way? (Just checked on my Polo, yeah that looks like T14a).

And does pin 11 of that just go to the PAS , not the MAF then, is that what you're saying?  If so, you could just take your new wire to there and also branch off to the MAF from the same point, cutting the original MAF feed?

On the Polo pin 11 looks to be second from top in front column. 

Yes i meant that pic. 

 

the cable that feeds 14.a, goes under the battery and then into the huge loom the same as the MAF cable. However - I think the other side of that connection / pin 11, went into a dark coloured wire, poss blue/black  - so I don't know where that leads to. 

[Breezy_Pete]

Hmm, so that doesn't go to MAF or PAS by the sounds of it, pity.

Do vRS's have oil level/temperature indications? That's possibly what is being fed by the dark colour wire from there (it should be black/yellow if there is). Have those indications disappeared too, if they were ever there?

[Thisday]

I don't think it does go to the PAS, as the PAS has a yellow/black wire, and its completley seperate from teh MAF wire as far as i can tell - I'm leaving work soon so will try and get a clearer pic of the connector/wires.

 

As far as i am aware there is no oil temp/indicator on the VRS, not that I am aware anyway (there is a temp on binnacle but that is coolant I am guessing)

[Breezy_Pete]

I think it would be in the multifunction display, selectable with the switch on the indicator wiper switch, where you see mpg etc?

Edited 1 March, 2016 by Wino

[Thisday]

ah pretty sure that's a no then - the only temp on there is outside temp indicator 

[Breezy_Pete]

In that case, I have absolutely no idea where that wire goes from T14a/11. Seems like it's no help to your MAF/PAS issue, but it would be interesting to know where it goes, 'cos presumably that item isn't getting ignition 12V either?

 

If it's black/purple, it might be going to the rad fan control unit, that's near that area.

Edited 1 March, 2016 by Wino

[Breezy_Pete]

Do you mean these?

 

I can't really remember but the arrows seem to be pointing at some sort of catches/latches. Not sure if the red ringed bits at the top are relevant

 

Edited 12 March, 2016 by Wino