boost gauge fitment questions

Ive got a mechanical smoked faced boost gauge that when the ignition is off is just black then when the ignition is on the numbers illuminate white with a red needle .. the gauge has 3 wires red orange and black ... red being ignition switch live. Orange being to side light live and black to earth .. what is the purpose of the orange wire?? The gauge needs the ignition switch live to iluminate so I dont see the purpose of needing a side light live ??

Secondly which colour wires on the headlight switch is a ignition switch live?? and which colour wires are the side light live?? (If needed) , as for earth ill just earth it off some metal work in the dash.

And which way have people routed the hose ?? Im taking it from the dv vac hose but dont no if I should route it into the cabin via the cable trunking behind air box and feeding it under dash to the drivers a pillar or by removing scuttle panel and going through the drivers side?? Just looking for the easiest and fastest route.

ive got to modify the leon pillar pod slightly and drill a hole in the a pillar trim to pass the wires and pipe through but ill do that at work tomorrow.

for reference the cars a 2002 1.8t sport aum engine

Cheers for the reply much appreciated.

I really dont want to mess with the relays to be honest do you know whst colour wire is ignition switch live at the light switch??

As for the orange wire ... that was what I was thinking but no mention of that in its instruction leaflet so im pritty sure now you have said it that thats what its for so ill get that wired up .

And yes its probably best to just take scuttle off rather than running a long pipe through under the dash.

Is that located under the fuse box ?? Drivers side under steering column?? Not quite sure of its location .. in rhe picture which relay is it?? There 3 but all seam to have wires goin to them??

Thanks again

Thanks for the information really is much appreciated.

I tested the gauge off a battery at work and the orange wire (side light live) is indeed to dim the light when the side lights are turned on so will be wiring that in .

ive removed my a pillar trim and modified the leon pod , had to trim around 5mm off the edge of the pod that goes under the door seal and reshape parts of the lower piece where the a pillar meets the dash but ive got it matching up quite well and looks good fitted .

will upload pics once complete

Got it all plumed in and working was really easy and straight forward thanks to vag-slags information.

I used the multi earthing point on the steering column for the earth . The nut under the 75 x relay for the ignition switch live and the purple and brown wire off the side light switch for the light dimmer thats built in to the gauge to lower the back lighting when lights are on.

the Hose was then through the gromet under scuttle panel on drivers side and fed up to the a pillar, I connected it to the vac hose on the dv.

looks smart and matches the dash dials really well so im happy with it!!

Will get sum pictures when I get 5 mins.

the turbos boosting at around 8 -9 psi.. is this correct for a stock mapped car??

Cheers