Ok got it done.
Black wire (wire closest to rear of car) has continuity to ground and battery neg
Key on, I get voltage to middle wire.
I get voltage from middle wire to black wire
Nothing on other wire closest to nose of car. I assume this is the return signal wire that displays the light
MAkes sense as it appears the sensor is not a contact float type switch, but works on magnetic inductance. So the hot wire and ground power the sensor, and when the float drops, a magnet trips it and you get voltage on the return wire.
OK. I got a chance to get to the car today to check wiring paths for the 86Gt OEM wiring and to voltmeter the 87-96 connectors with the pigtail wire that I cut off at the boneyard.
Note: No power was used here as my dash is out so I couldn't test this in an energized condition.
Refer to
@Mustang5L5 post above #21 to make any sense to my test below.... Again, a complete, confirmed, direction of current flow and wire each polarity is needed to come to any conclusion here.... Also the wiring diagram in a previous post by Mustang5L5 above is helpful.
My Test was done on the 87-96 pigtails OFF the car, but plugged into the reservoir, (this put the magnet in the float system in play) no power applied to anything. Using a voltmeter I get continuity between the Black wire and BOTH of the purple wires independently but only when I allow the float to drop down to actuate / complete the magnetic circuit. This means the circuit path (through the magnetic float switch) is completed through either of the purple wires.
Further test shows: when testing for continuity between just the purple wires, there is full time continuity there, regardless of float switch position. So, the two wires must simply be a (+) in-out loop. The trace strips on the wires are there to indicate direction of current path -ie. to the light or from the current source.
Now, I'm not certain which goes back to the warning light for-sure, (i don't have it all connected to the car); but that could be tested on the car by depressing the reservoir float to actuate the switch, and, if you care to cut one or the other of the purple wires to see if the dash light goes out, then test for current on the other you will get to the answer. Or...lol, you can just read the wiring diagram if you have it.
All this discovery appears to be good news for my plight as I've figured out on side of my plan. My dash is disconnected from my 86GT right now, so I can't power-up my car to decipher the polarity of the two wires coming to
my Brake Pressure Switch on the PV. This knowledge will allow me to determine to witch of those wires will I make my connections to get it all to work.
I PM'd a member to check on his 86 for me, but haven't heard from him yet...we'll see. This is where I'm at right now.