Ok, so I finally got around to installing the gauge.
I connected the red wire to the switched ignition, the black wire to a good ground (i wanted to use the one in the DME, Pin 28) and the violet wire that goes to the O2 sensor to pin 26 (a thin white wire, is this the correct wire?)

Well, after installing it, and making sure all of the connections were very good, I put the key in position 2, and the light on MAX rich stays on.
Then, when I turn the car on, the gauge STAYS at max rich, why is it doing this??

edit: problem solved, the correct pin is 24
What is pin 26 anyway?

 

Pin 26 is the reference sensor...

 

I installed by autometer af gauge (cobalt) this morning and had the same pb at the beginning. Probably coming from a bad wire. The signal should be between 0 and 1 V. I guess MAX rich means you get more than 1 V

I know have a different pb, the af ratio is hesitating between lean and normal and i have 4 o 5 leds illuminated together with hesitations...

I checked the signal and it is at 380 mV (+ or - 10 mV). I will try to make the connections correctly tonight (it's just a temporary wiring for the moment) and see if that solves the problem

 

don't forget that the lambda signal wire (pin 24) is shielded. first you need to open up the first housing, then you need to cut back the first wire you see. then there will be another housing with the actual signal wire inside that. the outer wire is a grounded shield. i soppose you could also tap into the signal wire at the actual pin inside the DME connection...

 

Yeah, I was stupid and lazy with this install . Asarus, I had the same problem, you're tapping the wrong wire. The right pin is 24, and I tapped the wire in the harness, refer to Dan's site: http://members.rennlist.com/951_racerx/ARM1install.html