Re: Coil wiring 98 Mercruiser 4.3 Thunderbolt Ign
 

Thanks Larry, I wanted to suspect the engine control module...but only because I know the least about it. I'm going to head down to me dock with my multimeter.
Which is the high vs. low?

Re: Coil wiring 98 Mercruiser 4.3 Thunderbolt Ign
 

High is coil output , low is power into coil.
Good Luck :)

Re: Coil wiring 98 Mercruiser 4.3 Thunderbolt Ign
 

Thanks!!!! I'm on it!

Re: Coil wiring 98 Mercruiser 4.3 Thunderbolt Ign
 

Ok Larry, it looks like it's the Ignition Control Module, mine is Denso manufactored. If I order it from Mercuriser it is nearly $600. Do you know of any Denso or GM applications that will work?
Thanks,
Mark

Re: Coil wiring 98 Mercruiser 4.3 Thunderbolt Ign
 

New - ICM 458.00.
Used - probably Ebay too.

Re: Coil wiring 98 Mercruiser 4.3 Thunderbolt Ign
 

Thanks Larry. The number on mine is 861251-1. Does the 861251T1 supercede the one on mine? My engine serial # is 0L037602. :confused: