[ischmitz]

Bill,

you are correct, the ICV bypasses the throttle body and thus it introduces metered air into the engine.

Both connectors (white 2-pin and black 3-pin) close to the 55pin DME connector are for coding plugs. These are inputs that are read by the multiplexing A/D converter in the DME and tell the software whether to use the O2 sensor and which ignition and fuel map to use. The switch is a logic value stored in the memory of the DME. The hammer will read this and tell you what coding the DME "sees". There are multiple sets of tables stored in the EPROM addressed by pointers.

The O2-sensor itself plugs into a round 3-pin connector on the DME harness close to the firewall. You need to connect an O2-sensor when coding the DME with the 3-pin plug. Else the DME will get "angry". The wiring harness for the O2 sensor if left open will pick up ignition noise like an antenna and throw the mixture all over the place.

Aftermarket chips typically disable the region plug by "bending" all pointers in the EPROM to the same modified map set. However, the O2 sensor logic typically stays active with these chips. So you do need the 3-pin plug with the jumper to B+

Ingo