Leaderboard

Of course, there is one other possibility. I could have designed the test wrong. I dug out a diode that should be the same spec as the ones used in the plug and tested myself. I found my instructions were lacking. You should re-test with the meter in diode testing mode. You can leave the key in OFF, too. If you test from the ballast resistor to the white/black wire, you should get a result similar to this: With the leads swapped, you should see this: If you do the voltage test, you should see a little less than battery voltage as the diode causes a slight voltage drop.

The upper perforations are for the vent, the lower ones are for the speaker.

Awesome.