jwacree

where this ? comes from. I'm swapping an engine in a 2005 S4.

Over the weekend i'm cleaning the engine wiring harness. workin from the big end down to the small ends. When I get to what turns out to be the alt, two wire pigtail. It's crunchy! upon closer inspection, all the insulation on both wires has crumbled! all the way to the ground lug and the relay!

Any idea what caused this?
What is the best way to repair, short of a complete new engine harness?

two90s

The wiring for the Secondary Air Injection (SAI) follows the wiring to the Alternator. If the wires you are referring to are heavy gage, ~10 gage wire, then they are for the SAI. There is a 40Amp fuse in the box for the ECU - chances are, it is blown. That fuse is for the SAI.
I had to re-wire my SAI not long ago, and these are some of the things I discovered as I diagnosed the problem. The first thing I discovered was the blown fuse, then the heavy gage wires with crumbling insulation. As I worked on it, I did not discover any other bad wiring, so I elected to just replace the bad wires and leave the originals in the harness.

Best of luck with it.

jwacree

Thank you, That's exactly what I did. I will go back and check that fuse. I discovered I was mistakin about where the wires connected. I have since moved along some.


I'm slowley makin progress.