msd 7 wiring ?

[ray jr]

i am wiring up my msd 7531 and would like you recomendation on the red+ and black - wires. does the positive wire have to go to the battery or can it go to a junction box. on the ground wire can i run it to the engine or should i run that to the battery. on a nother subject do you run relays for your trans. brakes and line locks? thanks ray

[Sparky]

I would follow MSD’s instructions and/or recommendations on the power and ground of the Digital 7. That way if anything were to happen to the ignition there won’t be as much finger pointing because you deviated from their instructions.

The use of a Relay on either Trans Brake or Line Loc is not something that is normally practiced. These items usually don’t require a Relay for a couple of reasons.
1.) Typically they only draw about 7 to 10 Amps.
2.) The amount of time you have either item activated is usually a short period of time.
Relays are typically used in applications where higher amperage components are not supported by toggle switches, (Water Pumps, Fans and Fuel Pumps, etc). Although a Fan doesn’t pull a lot of amperage while running, it will however pull a fair amount of amperage when first turned on and spinning up.
A relay is designed to make high amperage circuits more efficient and is better suited to carry the high amperage load. The toggle switch is only responsible for turning the relay on and off.

I hope this helps,
Sparky