Guage Install...Help Needed

I just bought a Cobalt Series Autometer A/F guage and I want to install it myself but I bought it from someone and he had already gotten rid of all the stuff that tells me which wire is which...there are 4 wires a long white one a black one a purple and a red one...

Im thinking the white is the signal wire to go to either the ECU or o2 sensor, the red for power, the black for ground, but I dont have a clue what the purple wire is for...if I am mistaken in any way please let me know...a 'how to' with pictures on this would also be a big help...

thats not working for me

That's werid works fine for me. Says the White is "12V Dash Lighting" and Purple is to the signal wire of the O2. Which is weird because it still says Red is to a 5 amp fuse which is connected to 12v ignition switch. But it says the White wire is only for Cobalt Series Model 6175. Black of course ground.

I just came out of the car the red is the power the black is ground...duh
the white is the light relay to turn on the blue lights in the guage at night...
the purple is the connection for the o2 sensor...i want install it so bad after seeing the lights just now but I cant find my ECU :( and i dont have a guage pod :( :(

Well I just got inside from installing the gauge...no I dont have the pod but who cares...it seems to be working...
I ran the wire from the o2 sensor instead of the ECU the hardest part of the whole install was not having the proper jack to find the sensor (used stupid honda jack) then when i found the sensor and plug i couldnt get it off...everything before and after those things we're quite easy...
I like this DIY stuff...I put it in, its working, no money out of my pocket...now all I need is a pod...For a RHD of course :D...

a narrow band af gauge doesnt read anything, its not accurate except at 14.7 stoich. you should throw it away

I really dont care to tell you the truth...so if your purpose was to be a kill-joy it aint workin...im aware that the autometer guages dont do much when it comes to being accurate and whatnot...but its cobalt, it has pretty lights, and it was cheap...cant tell me you wouldnt have got it...