My 1997 150hp rebuild

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Thanks
What is the bias circuit and you mean the
Idle speed control?
It sounds like the idle speed control box failed causing the switch boxes to fail.
ALSO I found the wiring harness 20 amp fuse blown.

 

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Bias circuit is in the switchbox and keeps timing on both switchboxes the same. Advance/idle module plays with the bias to ground circuit to advance/retard timing.

 

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So is the " advance module" the same as the idle speed control box?