MSD Marine box wiring
 

Hello All,
The MSD wiring diagram shows to use the red wire to turn off the unit. My Mecruiser used the purple wire that runs to the coil to shut things down along with the kill switch. I have been trying to reach MSD but no luck. What is the save way to wire the MSD unit, if I use the red wire I need to remove the purple coil and tach wires some help needed. Thanks Jeff

Which box are you running?

MSD 85701 Dist and 6425 6AL Box.

Connect the thin red wire from the MSD unit to the purple ignition power wire from the harness.

Important - The only connections at the coil should come from the MSD box. Do not connect the gray harness tach wire to the coil. See diagram below.

https://cimg8.ibsrv.net/gimg/www.off...372684c07b.jpg

One last note... I'd keep an extra distributor pickup on the boat. A spare box couldn't hurt too. They aren't the most reliable of ignition systems.

[QUOTE=TomZ;4806588]One last note... I'd keep an extra distributor pickup on the boat. A spare box couldn't hurt too. They aren't the most reliable of ignition systems.[/QUOI have a thunderbolt four now and have several plugs that read different. Im not 100 % sure its a ignition problem but leaning that way what ignition system would you recommend?

Msd
 

I can say this the technical dept at Holley is useless three days over 2 ours on hold and they are unable to answer the simplest questions. I basically new more than this guy.

The TBIV is pretty reliable… more so than the MSD. What’s up with your plugs?

I come here for technical support.