Mercruiser Thunderboat v Coil question

tank1949

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Manual indicates that coil is external resistor type. Where is the resistor(s) located??????? This is confusing. Help!
 

alldodge

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Manual indicates that coil is external resistor type. Where is the resistor(s) located??????? This is confusing. Help!

The TBV does not use an external resistor, if your coil states to use with an external resistor then you have the wrong coil.

Points distributors use an external resistor and it is the resistance wire (purple) which is feeding the coil
 

tank1949

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alldodge

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Wholesale marine links do not work at iboats

I'm guessing its a Sierra part and shows to use with external resistor, and probably also says can be used with TB4 and 5 ignition. That said, first I don't use Sierra parts but offer this.

Sierra part number 18-5433 has an internal resistor
Sierra part number 18-5438 requires an external resistor

Use which ever you want, they will both work. Also coils hardly ever go bad, but they get replaced a lot.

Don't know what motor your working on
 

tank1949

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Wholesale marine links do not work at iboats

I'm guessing its a Sierra part and shows to use with external resistor, and probably also says can be used with TB4 and 5 ignition. That said, first I don't use Sierra parts but offer this.

Sierra part number 18-5433 has an internal resistor
Sierra part number 18-5438 requires an external resistor

Use which ever you want, they will both work. Also coils hardly ever go bad, but they get replaced a lot.

Don't know what motor your working on

So where would the external resistors be located? Under helm? Back of block? ???? This is what is confusing to me.
 

alldodge

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The external resistor is a resistance wire, it looks like any other purple wire, but the one going to the coil IF designed for the use will have resistance in it. Many years ago when points were used they would actually install a ceramic resistor and mount it close to the coil. Since then they just make a wire which has the resistance built in.

Disconnect the battery and the purple wire going to the coil and the one on the choke. Take a ohm meter and measure the resistance between the choke purple wire and the coil purple wire
 

tank1949

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The external resistor is a resistance wire, it looks like any other purple wire, but the one going to the coil IF designed for the use will have resistance in it. Many years ago when points were used they would actually install a ceramic resistor and mount it close to the coil. Since then they just make a wire which has the resistance built in.

Disconnect the battery and the purple wire going to the coil and the one on the choke. Take a ohm meter and measure the resistance between the choke purple wire and the coil purple wire

THX!!!!!!
 
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