Well, I wanted to keep things as clean as possible, so I hooked up the ARM1's sensor wiring directly into the DME wiring at the connector. I tucked the remaining two wires (EGO signal & ground) high above the glovebox and wrapped it around the DME harness near the firewall down to the DME computer. I didn't want to risk shorting the EGO cable (coaxial-type shielded) by using vampire taps. So that means connecting to that wire inside the DME connector itself. I opened it up and threaded the sensor wire and ground under the rubber seal.
The signal from oxygen sensor comes in at Pin-24 and I found a good ground at Pin-28. Actually the ground was 0.005V below the chassis, so I'm not sure where the electron sink is coming from, but it was stable, so I used it. Taking out the metal pin to get a good solder joint can be tricky.
Pull gently on the wire with needle-nose pliers and release the catch tang with a small screwdriver. Kinda wedge the screwdriver tip towards the outside and you should feel a little "click" and the pin will release.
Then, you can unclamp the strain-relief and feed in the sensor & ground wires. Clamp back down tight and solder the joint. Make sure that the catch tang on the pin is bent back out so that the pin will stay put when you re-insert it into the connector. Then put the side catch plates back in and reassemble the connector. Zip-tie the rubber boot and that's it!
One of the most common problems that may arise after installation is that the ARM1 display doesn't behave as it should. How should it behave you ask? Well here's how:
idle - display should dither around the middle yellow dots (when
engine is warm).
medium-throttle less than 3500rpm - should also dither around the middle, but encompasses larger group of dots.
larger-throttle above 4000rpm - display should stop dithering and hold steady, slowly creeping upwards
full-throttle - display should be at 1st blue dot (last green is too lean, 2nd blue is too rich)
coasting in gear - steady on 1st red dot (computer has shut off fuel, you should feel shudder around 2000rpm as fuel is turned back on)