No spark thunderbolt 5.

BradHanks15 said:

Hi, I have a 03 crownline with a mercury carb 4.3 thunderbolt 5 ignition with no knock controller. Was wondering if anybody knew the wire colors on the coil? I have done the no spark test that’s on here and it’s leading to the icm, I just wanna make sure that the I have the wires back on the coil correctly. Thanks.

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BradHanks15 said:

Thanks for that. I found one on there so I’ll go ahead and buy it.

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Scott06 said:

I saw one relatively cheap a few years back and bought it for a spare. It is a shame they are so pricey as the TB is a really good ignition system

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BradHanks15 said:

I have done the no spark test that’s on here and it’s leading to the icm,

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BradHanks15 said:

Maybe I’ll have to keep watching for a spare as well. Definitely a shame.
Random question. Do you know how the icm actually controls the spark? Since the one purple is the 12v ign and the gray is a tach lead, I’m not seeing how the icm actually controls it.

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alldodge said:

That was the TBV troubleshooting guide, right?


The spark is triggered from the module in the distributor with the Wht/Red and Wht/Grn wires. The Wht/Red supplies power to the module and the Wht/Grn triggers spark when grounded. This is why the TBV troubleshooting guide has you strick the Wht/Grn real fast to ground

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