Is a main relay needed for MS3X Ignition in??

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redmist
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Is a main relay needed for MS3X Ignition in??

Post by redmist »

I am rewiring my entire car, and have eliminated the Megasquirt relay board. I am going to wire in my own relays. I am using a nice Ron Francis EXPRESS fuse panel for this install. Is there a need for a relay for the 12 Volts in on the megasquirt ECU itself?? It seams kind of redundant, but figured I would ask. My Ron Francis panel has a "Coil/ECU" terminal just for the application, but I don't think it's relay switched, I believe it's simply wired to the ignition switch itself.

I will be using relays for my Coils, Fuel pump, Electric fans, and injectors.

Thanks!
1968 Dodge Charger, 446ci 513HP/542ftlbs,Full sequential fuel/Spark using MS3X. Jeep CPS, Ford Crank sensor, 36-1 wheel, Coil near plug with D-585 ls2 coil packs. Edelbrock pro-flo intake, 600cc injectors, GM MAP, TPS, IACV, CTS, MAT. 92mm Throttle Body.
Ollie8974
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Joined: Tue Aug 05, 2008 8:47 am

Re: Is a main relay needed for MS3X Ignition in??

Post by Ollie8974 »

Yes the key activates the main relay to a 3 amp fuse.
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Last edited by Ollie8974 on Sat Aug 30, 2014 6:50 am, edited 2 times in total.
DaveEFI
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Re: Is a main relay needed for MS3X Ignition in??

Post by DaveEFI »

redmist wrote:I am rewiring my entire car, and have eliminated the Megasquirt relay board. I am going to wire in my own relays. I am using a nice Ron Francis EXPRESS fuse panel for this install. Is there a need for a relay for the 12 Volts in on the megasquirt ECU itself?? It seams kind of redundant, but figured I would ask. My Ron Francis panel has a "Coil/ECU" terminal just for the application, but I don't think it's relay switched, I believe it's simply wired to the ignition switch itself.

I will be using relays for my Coils, Fuel pump, Electric fans, and injectors.

Thanks!
IMHO it's good practice to feed MS direct from the battery, to minimise any 'rubbish' on the supply. Which would involve a relay switched by the ignition. In the same way as you provide MS with its own ground. I also do the same with the ignition power feed. That is the main source of 'rubbish' on supply lines.
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elutionsdesign
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Re: Is a main relay needed for MS3X Ignition in??

Post by elutionsdesign »

It's good practice to do what the OEM's do, they relay the power feeds.
Graduate of EFI University.

I build, repair, install and tune Megasquirt systems in North Dakota and beyond!
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