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TR2/3/3A Coil wiring


Freshman Member
the wiring chart has "CB" and "SW" notated - which wire is which? what does that stand for? Which is positive and which is negative?

Thanks for your help !!


Jedi Knight
Country flag
My guess is cb is circuit breaker for distributor - and sw is switch for +on a negative ground car.

Geo Hahn

Country flag
Contact Breaker & SWitch - in my experience those designations were on coils back when most Lucas-equipped cars were positive ground.

Later, when negative ground cars came into vogue, the markings were changed to + & -.

I think you will be okay by regarding CB = + and SW = -.


Country flag
I'm not sure it makes any difference one way or the other.

Generally, it makes no difference, as most of the time it will run regardless of the how the polarity of the coil is wired. However, there is a difference in how effectively the spark jumps the electrodes in the spark plugs depending on the polarity. Read this link for a full explanation...

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