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While I was tracing the secondary air injection pump issue on my S4-B6-2005, I had found that the electrical wires to the air pump are short-circuited because their insulation had been completely heat-damaged. The insulation got hardened by heat and broken into pieces and fell down all the way.
Because they are "12V-DC power lines to the air pump" so they would certainly carry larger amount of current than sensor wires, and henceforth, eventually they became more likely being heat-damaged than other wires.
I think those electrical wire harness should be "die-hard" such that the insulation needs to be strong enough to stay well under the S4's engine heat.
My vehicle has 100k miles now. I understand the wires also get worn out by aging. But I'm not sure if it is normal(?) to have such "wire insulation fail" at 100k miles.
I called to AoA and had described the issue. They said they would file the case however, maybe, most likely, they would not support anything on this because my vehicle has 100k miles already.
Am I expecting too much on the quality (reliability) on my vehicle?
When I showed this to a local indy mechanic in my town, he said it's ridiculously too early to have such issues at 100k. He had seen this kind of thing on MB performance vehicles, too. But their mileages were a lot higher than 100k.
Just updating in case any one else has this problem. The wires that go from the pump to the ecm box where the relay and fuse box are have a short, well actually they are touching together . So I looked and found this. Anyway this wire loom goes over the air box. My fuse kept blowing so I took apart the Sec air pump but it worked fine. I found the wires inside the loom with absolutely no plastic on them. Im guessing from the heat. Going to put in slightly larger wire to help with the heat and load. Here is a couple pics. Also dont bother trying to repair the current wire I got as far back as the right cylinder head and its still messed up so im just gonna run a new hot wire and run the ground to a short frame ground right by the pump. Only way to repair the harness is if the engine is already out. Wish I knew about this issue before I put the engine back in.
You can swap the wires wire with the engine in place. The wires comes out of the ecu box. If you remove a couple things up by the firewall you will see the wiring loom that runs along the firewall then under the air box and down to the pump. You can pull back sections of the loom covering and solder a new wire to the bad wire, then tape real good and than pull it through section by setion of the loom. Might need to remove some tape and then re tape in a couple sections. Thats if you wanna make the repair look good. Took me a couple hours. Went with a slightly larger guage wire with thicker insulation.
12-12-2011, 08:15 PM
Engine Electrical Wire Harness Insulation, heat damaged.
