1992 5.0L Thunderbolt IV purple wire 12V head scratcher!

[AKFISHRIPPER]

Ok guys I have quite the head scratcher but I'm sure it will end up being something simple. I have a 1992 Ciera 2452 with a Mercruiser 5.0/Thunderbolt IV ignition. The problem: Not getting 12v to my coil. So the purple wire that comes off the ignition switch splits off to each gauge for power than comes back into 1 wire that goes back to the engine harness and splits 3 ways to the coil, electric choke, and alternator. With the key on I'm getting 12v at the purple wire all the way to the engine harness but as soon as I plug it into either the coil, choke, or alternator it dies down to 3-4volts? I'm guessing something somewhere is shorting out bit can't figure it out? Any ideas guys?

 

[Bondo]

Ayuh,..... Pull, 'n clean the cannon plug, where the boat's harness meets the motor's harness,......

Also pull, 'n clean the battery's Ground connection to the motor's block,....

 

[Scott Danforth]

you have a bad connection somewhere.

check all your cables

all electrical connections need to be clean and shiney

 

[AKFISHRIPPER]

That's kinda what it sounds like, I was hoping it was something easy that I was missing but I guess it would be good preventive maintenance to church up all the connections anyways since this boat has spent most of its life in the saltwater..

 

[Scott Danforth]

clean all connections..... by clean, clean enough your wife would eat off them.

then when all connections are clean and tight, seal them with marine electrical varnish.

 

[AKFISHRIPPER]

I was gonna ask if there is some sort of spray protectant kind of like the red stuff you put on automotove battery post

 

[AKFISHRIPPER]

Just went to the local Mercruiser mechanic and picked his brain...he's thinking it's my shift interrupt switch. Going to run a new purple wire with splices to the coil, choke, and alternator then disconnect the interrupt switch and test it. I'll give an update tonight

 

[Bondo]

Just went to the local Mercruiser mechanic and picked his brain...he's thinking it's my shift interrupt switch. Going to run a new purple wire with splices to the coil, choke, and alternator then disconnect the interrupt switch and test it. I'll give an update tonight

Ayuh,.... To test the shift switch,...... Just Unplug it,........

 

[AKFISHRIPPER]

Thanks for all the ideas guys...I got it figured out! Can't stand when someone doesn't post the results once the resolve an issue so here's what I ended up doing..

#1 I rewired the purple wire from the engine harness to the coil, choke, and alternator which fixed nothing
#2 I bypassed the kill switch and that did nothing
#3 I bypassed the Shift interrupt switch and that did nothing
#4 Went through all 5000 electrical components including battery post, engine grounds, outdrive grounds, splices, and wire connections with a wire brush and carb cleaner...FIXED!

One of the 2 main engine ground bolts was rusted really bad so I replaced it with a stainless bolt and I'm pretty sure in the end that was the cause.