Engine Bay Live Feed?

i am about to fit a Tuning Box to my TDi 75. It needs a permanent live +/- supply to function. I admit I haven't ( yet) lifted the engine cover/bonnet but with the battery in the boot is there an easily accessible/visible supply to connect upto under the bonnet? It is a device used on my previous A6 TDi which I have had re-programmed by the importers and a new loom made up to suit the 3 pot engine. I will post elsewhere when fitted with my impressions.

Hi Adrian.

Had exactly the same problem with mine.
(Was mine but now sold to my daughter with Box removed!!)

Might not be the best way but, couldn't find any live feed under the bonnet so I took up the carpet in the passenger front footwell and lifted the cover to the compartment below. I pushed a cable through the rubber grommet on the floorpan and routed the cable, with cable ties up in to the engine compartment and once connected to the Tuning Box, connected the other end to the positive terminal in the footwell.

Initially, I connected the earth to the mount for the engine cover and couldn't understand why I didn't get the extra power! Make sure you choose a good earth.

If you need any more help, PM me.

Regards

Chris

Hi Adrian
I seem to recall one club member picking up a live feed from the reverse light switch for his tuning box. The switch is on the side of the casting, just below the counterweight on the gearchange cable mechanism and points diagonally towards the nearside headlamp.

Cheers Spike

Spike is quite correct, as usual.

Look for a 1mmsq. black and white wire going into the switch - that is the post-ignition feed, the other wire going to the switch is the same thickness and is black and red.

Cheers,

Mike

Thanks everyone for comments. To clarify, the black and white wire is '+' and the black/red '-'. Or is there another earthing point to look for?

No, no - the black and white wire carries a post-ignition (i.e. switched) 12 volt feed, but the other wire is NOT an earth or a negative. Ordinarily it carries no current at all and only when reverse is selected, a circuit is completed in the switch and then the 12 volt feed carries on out the black and red wire on to other components.

There are loads of earthing points in the engine bay, either look for bare chassis or thick all-brown wires, which are always earth in Audi wiring.

Cheers,

Mike

Thanks Mike, it is a long time since I used to get involved in the interesting bits of a car, brain becoming rusty! Had plenty of 'experience' of working on Audi/VW engines years ago when I couldn't afford to pay someone ( and they were simpler). Replacing worn valve guide seals was a particular 'favourite' job of mine, not! Did that on a mk2 80, mk 1 Scirrocco and mk 1 Jetta Gli ( nice car that).