I spent some time working over the harness on my F4i gauges using forum info. Some things didn't match up so I pulled up some wiring diagrams and sorted it out.

Then I screwed up.

I needed an ignition+ line to activate the gauges. On the F2 diagram, there's an ignition+ source that feeds the oil sensor indicator.

It turns out that that line ALSO gets grounded when the ignition is off.

I now have a lovely new $130 paperweight for my office. Maybe I'll turn the tach into a clock or something.

Grrrr.

 

After putting the gauges on my bench for a while, I pulled out my bench power supply and played around a bit. It turns out that there are two ground lines in the F4i gauges. A green and a green/black wire. One takes care of the illumination ground and the other handles all of the gauges/indicators except for the brights indicator, which is on the first ground plane.

I didn't have green/black grounded, which made the display only come slightly to life and convinced me that the gauges were fried.

Now they're wired up and I just need to spend some time building a speedo sensor.

 

Please share your results! This would be awesome!