Thanks jim for your support.

In answering your questions, the air pump is cycling properly for about the first 90 seconds at startup. Although that doesn't negate that the valve (name escapes me) is operating as well and sending air to the exhaust manifold.

I am attempting to interogate the system but was getting confused at the voltage readings I was receiving at the O2 sensor connection at the x11/4 terminal 14. I don't have a VOM with a duty cycle, but I was measuring the voltage at the output and was getting most of the time 7 volts static. Sometimes it did dip between 1 and 2 volts, but not very often. I was thinking that I should see between 0 and 1 volt but I'm guessing now that it is the translation to a percent of car voltage (not o2 sensor voltage) that is really being sent from the computer to the x11/4, position 14.

I'm trying to check the continuity of the wiring harness between the ECU and the o2 sensor connector beneath the car. I now have the pinouts but am trying to rig a system to check the voltage whilst the car is running. Short of pulling the ECU and probing I'm at a lose on where to make a connection. Any thoughts?

Ron

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1995 E320 -171k-km
1995 S420 -333k-km