Brendon Taylor

So, i have a really sweet garaged no rust v6 model a4, and the clutch and engine are pretty rough- i also have a sweet 1.8t engine with all new performance turbo, intake, cat and exhaust to go with it.... I really want to put in the 1.8, and everything seems pretty straight forward- subframe, wiring harness and evap canister need to come out of the 1.8 car (which i still have, so i have everything i need) ecu plugs all match except for one wire in one of the plugs under the ecu, going in to the cab..... the 1.8 harness has an extra pin/wire in it.
Does anyone know what the white plug is responible for, and if yes, any chance you know what that extra wire goes to? any help is greatly appreciated!
First pic is all plugs, second pic is the connector with the extra pin (1.8t harness) and third pic is the v6 model

Brendon Taylor

They are both 2001 models, made a couple months apart from each other BTW

David.Norton

I can't tell from the schematic what the difference between the 1.8 and 2.8 connectors are, it is pretty cluttered. If you could put a color (or pin number, I've seen some of the connectors have the numbers molded in) to the extra wire I might be able to tell. BTW the connector is for the cruise control and the throttle position sensor.

Brendon Taylor

Thank you SO much for responding, i really appreciate it. the wire is red with a blue tracer, and its the middle slot on the side with big pins- doing my best to pinch and separate the wire in the pics

David.Norton

Alas I'm not sure I can help, I don't think you are in the same market as I am. My schematics are for the US cars, the only heavy red wire in the ECU box is on a black connector, not white, so I wouldn't trust my information for your car. My schematic also has the stripe on the wire you are holding as grey (and to be honest your picture looks grey to me, the blue on the connector looks blue), if it is anything like the schematic I have the red/grey goes to a 15 amp fuse, and then to an actuator for camshaft position on the engine. But again, don't take this as absolute truth, you might consider adding your location so someone in the right market can help. Good luck with it.

Brendon Taylor

Yes, yes! That is exactly right… I didn't want to believe it, but I did trace that wire to a 15 amp fuse right next to the ECU, and then followed it to the rear cam position sensor (thought it was entirely possible that I was mistaking that wire) I didn't want to believe it, because it didn't make sense to me that the cam position sensor would be sending anything to the inside of the car ( but I am no expert, hence my messages to you) so- The million dollar question is, is this wire just a power source for that sensor, or is it sending in sensitive information to some computer chips inside? If there's anyway you can figure out what this wire is responsible for, I will be forever in your debt! Thanks again for you time

David.Norton

Hi again;
I'm not sure what is missing, but here is the schematic page showing the cam actuator and that fuse. Looks as if the line is power switched though a relay near the ecu box (the grey box at the top is the fuse box, line 30 is hot from the battery at all times). The number next to the wire color is wire size in mm area, so the 2.5 is a large wire, the .35 are small ones. Hope this helps.

Brendon Taylor

Awesome, thanks- i think i might have a grip on this wire, but i have to say, it's been difficult trying to find a diagram that just shows those connections under the ecu and what connection is responsible for what... with all of the buttons and controls being EXACTLY the same in the cab, i would hope, for productions sake, they would make the wiring inside the exact same- still paranoid though, so i would love to see a pic/diagram laying out those specific connections, if you have any insight/suggestions where i could find that, again, i would be in your debt-thank you

Brendon Taylor

And on a second note, if the fuse boxes are the same orientation, would that suggest the wires going to those ecu box connections are the same? (for the most part)