Doubt the BIRD is bad? When you disconnect the purple wire you should hear the Trombetta relay open or close with a loud "clank." With a voltmeter connected between the large terminals of the Trombetta you should see the voltage change from a volt or so to a few tens of millivolts (0.010.) The Trombetta is junk as far as I can tell. Mine closed with a noticable clunk but the contacts stayed open yielding the function of connecting the two battery banks together void. I replaced mine with a White Rodgers 15V coil. About same money but far lower coil dissipation.
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