At 01:24 PM 10/20/2003, you wrote:
[snip]
>  the problem is that the AC model(AFS-75) has a male 3 prong end
>and 4 wires to it and the Bosch(#15703) has a 4 prong female.  Going from
>the Haltech wiring diagram, they have a wire carrying the 13.8v, a ground,
>and the O2 sensor wire.  The new Bosch has two white wires, a black and A
>GRAY.  If I  went strictly by the Pin A/Pin B/PinC set up, I believe I
>would have some wires mismatching.

I just recently switched my subaru 3-wire O2 sensor to a 4-wire Bosch....

The Bosch 4-wire sensors:

White(s) = Heater. One goes to Ground, one to +12v.
Black = O2 sensor signal
Grey = O2 sensor ground.

The sensor element is NOT grounded to the sensor body like the 3-wire sensors.
The grey wire must be grounded to the vehicle ground, preferably at the
same place
as the ECU logic ground.

If you put 12 volts on the sensor wires you may damage it, so tread
carefully...

Happy motoring,

Steve
EJ22 -> '86 Westy "Escape Pod"