Hi Everyone,

I am stumped on wiring my msd 6al box, and would like some help. Originally I had ran the small red trigger wire to the factory ballast resistor on my 69 RR. It was connected to the left side that had only one blue wire. I removed the resistor in the ballast resistor, and soldered in a 10 gauge wire across the ballast resistor. I wanted to keep the ballast resistor on the firewall for the factory appearance. This worked great.

I have now removed the small red wire from the ballast resistor, and ran it inside the car. I would still like to keep the ballast resistor on the firewall.

This is where I am confused, were can I connect this small red wire inside the car. Does it not need to see 12 volts when cranking and also when in the run position?

I have it connected to a switched accessory 12 volts at the fuse box, but this does not see 12 volts when cranking. It only see's 12 volts when the ignition is on. I can't see how this will work.

Can I also leave the ballast resistor jumpered?

That will be fine, just power on with key, so anything with power on when the key is turned, I normally connect it to the ignition, but you can connect it anywhere there is power when you turn the key. The heavy red wire has constant power and thats all that matters, when the small red wire sees power it turns the box on.
Think of it like the "remote" wire to an amplifier, except with no stop... Ideally the original pos from your coil wire in the harness would be perfect and you will have no problems, but I have wired the box in the car before and used wire from ignition. put a test light on it and turn the key on it lights, then turn the key if it still lights, good..


PS- I am not a fan of leaving hot wires anywhere that are not needed, so I would not leave the ballast jumped. I have used red silicone hose to appear as wire before...

what are you using for tach? stock?

when i did the msd on my car, i soldered two connectors in series for the turn on wire for the msd. i just plugged them into the bulkhead on the firewall in the right spots...the two wires that power the ballast resistor in either crank or run.
my situation is probably a little different than yours because the wiring in my engine compartment was already pretty ratty from previous owners...

All of the MSD units I have installed needed 12 volts in run and start posistion on the smaller red wire. I had to also tap the red wire into the ign 2 terminal off the ign switch or it wont get spark until you let the key back to the run posistion. Basically it needs to see the ign 1 & ign 2 to it so it has power in the crank and run mode. Ron

Thanks everyone for the feedback. My aftermarket tach is wired to the MSD box.

I decided to wire the 6AL box the way I had it before, which see's 12 volts when cranking or 12 volts in the run position. I took the feed off the ballast resistor, and ran the wire inside the car.