In my wiring diagram the DK blu is the positive. Ignition switch,alternator,voltage regulator 6 pin connector,spark control computer,egr solenoid,air sw solenoid. On a Ford they always pulse the negative Blk YEL wire. It also goes to the spark computer. I would suspect the spark computer as the signals from the distributor also go to it. As you have a six pin connector I would ohm the wires between the coil and spark computer. Same color all the way.
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