LS1 Fuel level sender issue

[HAMRHEAD]

Trying to program an Autometer Cobalt fuel level gauge and it isn't going well. What the hell am I doing or not doing right? Here is what I got so far.

Red wire = 12v This is good and gauge has power.
Black #1 = Engine/chassis ground. This wire is good.
Yellow = lighting. This is good!
Brown & Black #2 = programing wires, they are good.
Purple = signal wire, not working right.

I used a meter and checked the ohms coming from the in tank sender and they are good. However I get no reading from just the purple wire. I only get a reading when I use the meter on the purple and the black with gray stripe wire. The directions say to run the purple signal wire to the signal wire of the sender. Which to my understanding is the purple one.

Why is this not working? The gauge goes through all the steps but fails to read proper fuel level at the end so I always need to repeat it and it just won't work.

Pics:
http://img.photobucket.com/albums/v355/hamrhead/fuel0041copy.jpg

http://img.photobucket.com/albums/v355/hamrhead/fuel0021copy.jpg

The arrows are the two wires I use to get the proper ohm readings from. What am I screwing up?

[forest]

put an ohm meter on the purple wire and move the level up and down, see if it changes voltage, it if doesn't then you got the wrong wire. If it does, ground the gauge to chassis direct not harness ground, see what happens.

[HAMRHEAD]

I put the meter on the purple wire and got nothing. For the hell of it I did it to the other wires as well and nothing. The only time I get the right reading is when one lead is on the purple wire and the other lead is on the black w/gray stripe wire as in the pics. 40 ohms empty and 250 ohms full. This is really starting to confuse me. Any ideas what the problem could be?

[forest]

is your guage grounded?

[brotherbenn83]

That's how it works, you cant get a resistance measurement of just one wire, unless you are checking that wire from point a to point b (example, from tank to dash) The two purple wire coming off the sending unit change in to purple and the black/gray you mentioned. You need to use both wires to get that proper 40-250 Ohms reading.