Problems with my autometer gauge

[It's a 5_0 HO]

Okay guys i purchased the autometer air/fuel gauge for my 95. I got the meter reading the O2 but the back light will not work. It is the cobalt series. It has only three wires out the back. Red for power black for ground and the purple for the O2 sensor which i tapped into the ecu the gray and light blue wire. Anyone think of anything that i may have done wrong when i wired it or is it just defective.

 

[95cobraguy]

i'm prety sure the air/fuel gauges aren't backlit, i know my ultra-lite wasn't when i had it.

 

[It's a 5_0 HO]

well i removed the sticker on the back and im pretty sure a bulb plug goes there, but it didn't come with the gauge itself. So now i guess in the morning i will call jegs and see what is up with it.

David