4b - Best Way to Wire Delco EST Upgrade Kit into a TB V Harness

In this video I’ve updated and improved the wiring changes to install a Delco EST Ignition Upgrade kit into a THUNDERBOLT V harness on a 5.7 Mercruiser engine. However this applies to any size engine with a TB V ignition system.
This method is the easiest to do and faster.

[@AchikSarih]

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[@jasonhosking8439]

I might be missing it, but is there a spot in one of the videos that shows the shift kill white/black, and red wire on the harness on the shift kill switch itself, or are they connected together?

[@moccasinmarine]

The shift kill switch is a micro switch mounted to the shift mechanism. It doesn’t get connected until the shift mechanism is attached to the exhaust after the engine is installed in the boat.

[@jasonhosking8439]

@moccasinmarine thank you, so there is nothing saying where the red wire from the distributer, and the white/black get connected? That's why I was wondering if I missed something in another video...appreciate it.

[@jasonhosking8439]

My TB V had two wires on the old coil, purple, and the grey/white that you left abandoned on the old TB harness, have you ever seen that?

[@moccasinmarine]

Yes that’s how thunder bolt IV systems are wired. One purple from the ignition switch providing power and another purple leaving that powers the Thunderbolt IV module.

[@jasonhosking8439]

@moccasinmarine so the grey and white wire must be the grey wire that goes on your ignition coil? I read that they are all grey but I see no other option on mine...it must be spliced somewhere to go back to the tac?

[@moccasinmarine]

@@jasonhosking8439 I’ve never seen a gray and white wire. The colors are too close together to be distinguishable. Are you sure it’s not just a white wire with dirt?

[@jasonhosking8439]

@moccasinmarine 100%, and a continuity test confirms it is the one that is abandoned on the TB V harness. I found a diagram that shows that wire is spliced into a run from the harness to the old TB module.