76 2.0. When I put my auxiliary air valve on the bench and hook it up to 12 volts it works fine. But in the car, it wouldn't work, so I checked the brown wire lead that the air valve lead wire plugs in to. The brown wire that the air valve lead plugs in to powers up to "negative on" when the car is started, not "positive on"! That can not be right as the auxiliary air valve can is the ground, so the lead from it must need a "positive on" when the car is running. The brown wire seems to lead into the wire bundle that tracks back to the ECU. I do not want to open the ECU until I understand more about what is going on. Why in the world would the brown wire connection for the aux air valve wire be "negative on" when the car is started? HELP!

If you're hooking it up to a brown wire, you're hooking it to the wrong thing. There should be a white wire that gets power when the fuel pump is on.

--DD

Here's a picture of the two wire leads coming out of the bundle. The green and red striped wire goes down to a sensor on top of the engine and the brown unhooked connector was connected to the aux air temp lead and is "negative on". If I need to run a new correct white wire to the aux air valve lead (since there isn't one there now), where would be the easiest place for it to originate from?
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Does the wire that you are trying to connect to the AA valve have voltage present when you say it is "On"?

You really need a volt meter to troubleshoot these cars.
I just bought a $10 one at harbor freight the other day that works fine, they are just "delicate".

Then we could also explain how to check the valve for "continuity" on the bench and on the car.

The brown wire has no positive voltage to it when car is off or on, and only when the car is started does the brown wire becomes ground, or negative. Does that make sense? Where would be the best place to connect a new positive wire to run to the auxillary air regulator lead?

Aux Air Valve connects to a wire coming from the #12 pin on the engine wire harness from the engine bay relay/fuse panel. Can't remember what color. It is powered by the fuel pump relay. It does not come directly from the CPU harness (all white with numbers)

Thanks Mike, at the risk of asking a dumb question, but to be sure I'm at the right connection, where exactly is the engine bay relay fuse panel, under the cover next to the voltage regulator? Is the #12 pin marked with a number or some other way to identify it? Also, any idea why the brown negative wire lead, only grounded when car is on, exists at all in the area of the throttle body?

here's this
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Looks like it might actually be white
Yours may just be dirty and look brown. Pull that plug on the relay and board and check continuity with a volt meter.
If you fuel pump works then that pin would have to have 12v pos.

The wire in the photo looks like a white wire that is old and stained. They get that way.

Are you checking correctly? "Negative power" isn't much of a thing; perhaps you had the probes of the voltmeter switched around?

The D-jet ECU runs the pump for about a second and a half when the key goes from off to on, and then runs it again when the engine is running (as determined by the FI trigger points opening and closing). The rest of the time that wire should not be connected to anything.

--DD

Got it working! You were correct, that was the white wire, had a bad connector on the end, not sure what I was measuring but it powers up the aux air reg, which closes completely in about 2 to 3 minutes. Thanks for your help!