Extra Wiring and Plugs under the hood

[Marc Boucher]

My Audi 100 has a couple of extra, unused plugs under the hood.  My guess is that there is a standard wiring harness shared across different models and some of them are simply not used on some models.

I came across one today that was curious and unique...hadn't seen it before because it was twist tied and hidden behind the vacuum accumulator.  When I pulled it out it consisted of on thick black wire insulation that leads below the fan and enters interior through the major set of wires directly over the steering wheel (not through the one behind the coil).

This wire itself had three plugs underneath.  One was a standard two pin plug (I'll call it a bosch plug) that's used for example on the cold start valve or the thermotime or the diff pressure regulator.  The other was actually two single wires with a rubber boot over each; These appeared to be a pair.  These two wires measured 12 volts across with the ignition engaged.  The other plug (the bosch plug) measured 5 volts across.

My "guess" is that these are the original wiring for the Oxygen sensor.  I guess this because it appears that the O2 sensor was later rewired using somewhat different looking plugs.  

The reason I ask (other than curiosity) is that I'm looking for a bosch plug that I can cut off and use to test the cold start valve with direct 12V.  Right now I'm measuring everything using alligator clips or holding the wire in place.  I know there are test harnesses you can buy or build but if the plug is not likely to be used I thought I'd just cut it off and tape the wires shut.

Marc