Charles Lasitter wrote:

<snip>

> So there's this lovely item that dispenses with all that fuss.
> That's the "Test Harness" for the vehicle speed sensor. It plugs
> inline between the sensor and the wires leading away from the sensor,
> and you could tap into THAT bit of wire without ever disturbing the
> OEM setup.

Understood. I am involved with an older car where the fuel pressure
regulator is controlled by the ECU (the mixture is controlled by varying
the fuel pressure rather than by varying the duty cycle of the
injectors). The oxygen sensor can be tested by reading the current
through the fuel pressure regulator. Problem is, to conveniently measure
the current you need a factory test harness similar to what you are
describing for the VSS. For that particular car I have found that the
connector for the oxygen sensor is the same as for the fuel pressure
regulator. At the junk yard I was able to cut out both the male and
female O2S connectors, and have made my own harness. Total cost $4, your
dealer probably wanted a lot more for the VSS test harness?