Ok, so i got my Megasquirt-II in and running today, but i have only 1 problem. Me and my uncle cannot for the life of us locate a line that supplies 12v during run AND while cranking. The Megasquirt manual says to use the "Main" relay, but i dont think there is a "Main" relay on this car. I have used a multimeter to check them all (i thinK) and it cannot be found.

Checked my Haynes Wiring Diagram, checked the Autozone website Wiring Diagram, just cannot find a source.

Please help, i have to leave for work tommarow by 2:00pm and need to have this hooked up. Otherwise i have pretty much rough tuned it and its pretty driveable.


Thanks

 

Why do you need a line that is hot in both run AND cranking? I mean, other than accessories... anything on the ignition circuit is hot during run and cranking.

I wish I could tell you a simple answer and which wire to go to. You could try the nice 14 gauge yellow ignition wire under dash.

Otherwise find a lower amp circuit which is hot during run and crank and have it power a cheap 30A relay and make your own run from fusebox or batt (be sure to add an inline fuse for later) to where u need the power.

Alot of people get choked up on understanding relays,, but all they are is a remotely powered switch for a 2nd not necessary or at all related circuit. It allows a low current switch/circuit to remotely engage/disengage a usually higher amperage switch (relay). This allows for shorter runs from powersource (batt) and less voltage drop (resistance)

Fuel pump, ign coil

 

Well, it needs to be hot in run AND crank because the Megasquirt is going to be injecting fuel and doing spark, so it needs to do this while cranking or else it wont start

Ok, Yellow ignition wire under the dash, i think that sounds like a good choice. I dont want to cut into the factory engine harness because i will be selling the Intake, TB, Computer and Harness on ebay when i get my Stealth Ram setup.

Thanks for the help!

 

yw

you could piggyback off of the fuel injector fuse and use a relay. That would eliminate any splicing.

 

Find the fusebox in your haynes manual. The circut with the ECM fuse will be hot in run AND crank. The wire coming from that circut was the same color as the power wire on my ECM. On my 84 L69, there is a pink/black wire that goes to the ECM harness. The other side of the fuse box was orange or red, not what you want.

Just splice onto the wire by the ECM's connnector. Then run that to the turn-on on the relay board, or to pin #28 on the MSII itself.

The fuel pump is a seperate relay, and sounds like you have that under control.

The injectors have a seperate(fused) positive hookup, and are grounded through the ECM.

If using the relay board, you could tap one of the orange wires behind the fuse box for the +12V Source.

That should be all your power needs, correct?

If you have any other questions or would like to share anything, I'm installing my MSII on my L69 engine using a TBI setup. I've managed to get the wiring puzzle solved, but I'm still fighting some new fuel lines.