UK-POLOS.NET - THE VW Polo Forum

Been trying to find the sense wire on my polo 9n for awhle and cane across this wire. In short, i broke my old battery as kept running the car for extended periods without the alternator self starting of revs. Alternator works but only oututs 14.2-.4 volts when i rev the engine to 2k RPM, which is never fun on a cold day. After reading forums figured out its to do with a potential broken wire (also no battery light on dash ever). So i found these 2 cut wires underneath the car maybe a few feet under where the battery sits. Are these the correct wires? If not where would i find them.[/img]

Yes colour wise and location wise it could make sense, however these DF and D+ wires usually go directly to the alternator and not to a coupling station.
But if you see such a broken wire, always repair it anyway.

When you remove that plug/socket, you should be able to clean it up and find its VW Group part number, that will allow you to buy in a new connector, you will also need to buy in a "repair wire" that is the correct size/gauge for that repair and one that has the correct connector pins on the end of ut, ie male or female, The idea is that you just cut this repair wire in half and open up that protective cable cover and join to the broken/sheared ends making sure that the repair sections are covered in heat shrink and reside within the cable protector.

Unplug the connector that has the sheared off/broken wire, cut it open and work out which colour of wire went to which pin, and use that info when reconnecting the wires.

Or, considering the age of this car and so its remaining life, after working out which wire goes where, remove the other connector and after finding out which colour of wire goes to which pin - record this as you can't always trust that VW Group continue using the same colour of wiring "through" a connector, chop that connector off and just join both pairs of wires back up using an extra length of wire if necessary, fit adequate protection to these wires and probably secure them to the mounting clip for the original plug-socket to prevent them shearing again quickly.

This shearing of these wires tends to be a TDI speciality due to the engine moving around a lot! Lots of reports of this happening to Fabia/Polo/Ibiza starting maybe as far back as 2001!

As always - check the charge warning light comes on when the key is turned to the first position, but you know that.