Re-purposing blue and brown wires/ load capabilities

[GreenFish]

So after a discussion about starter buttons it seems to be a better option to use the brown and blue wires from the engine harness to power my megasquirt EFI.

My question now is if I use the blue and brown wires combined to power the ECU/injectors/fuel pump/coils etc. I am running all of that off of an existing/factory fuse right?

Then I'd be using additional fuses out to each component.

Would I be overloading the initial fuse in the factory fuse block which I think is probably a 20A? Should I just by bass that fuse or put a large 30A in there just for piece of mind?

What do you think would be the safest/best option? Right now I'm just using a large primary wire from the battery running a separate circuit on a toggle switch but I'd like to make it less "rigged"

[HP_Cuda]

The blue and brown wires which go to your ballast resistor?

Don't you need a straight 12V all the time for megasquirt?

[GreenFish]

The blue and brown wires which go to your ballast resistor?

Don't you need a straight 12V all the time for megasquirt?

The brown one is hot when cranking, the blue is hot in run

[HP_Cuda]

So then you only want to tap into the blue wire, which was my point.

[YellowThumper]

As previously mentioned both ate needed.
While one is hot cranking the other is dead.
Stop cranking it goes dead and the other becomes hot.

GreenFish
Use those to power a relay. Your relay feeds the ms.

As a side note I tapped into my fuse block inside the car for the relay that is powering my ms. Hot cranking and also in run. But is not powered in the accessory mode. I will look and see if I can get a pic or ID location of it.

Mike

[GreenFish]

So then you only want to tap into the blue wire, which was my point.

You need 12v in both for the MS

[GreenFish]

As previously mentioned both ate needed.
While one is hot cranking the other is dead.
Stop cranking it goes dead and the other becomes hot.

GreenFish
Use those to power a relay. Your relay feeds the ms.

As a side note I tapped into my fuse block inside the car for the relay that is powering my ms. Hot cranking and also in run. But is not powered in the accessory mode. I will look and see if I can get a pic or ID location of it.

Mike

Yes, that is sort of what I was getting at. My 12v now is right from the battery to the relay. Ill just replace my hot wire from the battery with a wire that splices the blue and brown and then goes into my relay ..

Right?

So do i need to worry about the factory fuse at all?

[YellowThumper]

Yep on the first.

No on the second as triggering the relay is a minimal power draw.

Really itching to get back at mine.

Good luck

[GreenFish]

Yep on the first.

No on the second as triggering the relay is a minimal power draw.

Really itching to get back at mine.

Good luck

perfect.. thanks

[dodj]

put a large 30A in there just for piece of mind?

Yes, trigger a relay with the brown/blue wire combination, but don't ever switch out a 20a fuse for a 30a!

[HP_Cuda]

Ahh you just wanted to trigger on the blue/brown - make sense.

If you are going from the relay you are already halfway there.

[Chryco Psycho]

You can shunt power from the start relay on the inner fender to a second fuse block & run the extra circuits from  second fuse block & use a heavy relay 40amp to power off the secondary fuse block , the coil packs should be ok as well as the ECU from the existing Blue/brown wires , the injectors are powered from the ECU , but  the fuel pump is better run from a relay

[GreenFish]

You can shunt power from the start relay on the inner fender to a second fuse block & run the extra circuits from  second fuse block & use a heavy relay 40amp to power off the secondary fuse block , the coil packs should be ok as well as the ECU from the existing Blue/brown wires , the injectors are powered from the ECU , but  the fuel pump is better run from a relay

Good idea too, ill consider that also.

[YellowThumper]

Effectively that is what I did for the fuse/relay block I have up front.