Re: electrical question
I'll try.
The trigger output is a sine wave, which is in step with the crank, and increases in voltage as the engine speed increases.
The bias voltage is related to the level on the trigger waveform that fires the CD ignition. It is developed by the switchbox and is roughly half the peak voltage of the trigger signal. The firing point on the waveform is not zero crossover, but some ways up the side of the sine curve.
By tying the bias circuits together, small differences in the switchbox circuitry are ballanced, keeping the firing pulses (which alternate between switchboxes) even.
Magic add-ons, like idle stabilizers, and advance modules do their magic by pulling the bias toward ground to advance, and away from ground to retard the timing.
There is a simple jumper between the bias terminals to tie them together. To troubleshoot some ignition problems, you remove the jumper, as a bad switchbox can booger a good one through the bias circuit.
Which begs the question, Why do you ask?
John
