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simple wiring question


taylor76zharris

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I'm reaching the end of my megasquirt install but I've hit a snag. Where is the best place to tap 12 volts for the injectors and for the distributor? I don't want to source 12 volts for them all from the same place and I don't think that's how it should be done but I'm no expert. Also I'm also doing the install with a relay board from DIY autotune. So where's the best place to get 12 volts for the distributor and the injectors and how many times can I tap the same wire for 12 volt? Thank you.

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you could.  The injector wiring shown on the DIY site powers 2 banks of 3 injectors only.  So 2 wires to 3 injector positives, 2 wires to the other 3 injector positives, That took up the entire 4 slot 12v feed..  I don't think powering the distributor would hurt in either of those 4 positive slots. Its only an LED so it doesn't draw much I would just be concerned with noise but you might be ok. Read about noise.  You probably will have it at some point but maybe you'll get lucky.

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Awesome thanks! I tried to do my best to get away from any interference with the distributor wire but I understand Noise is a pretty common problem with this type of it install. I hope I get lucky and don't have any but I'm not counting on it. 1 last question on the relay board there is a large port for an engine ground will that take the place of the 5 ground wires in the DIY wire harness? Because I noticed when looking at pictures and when doing some research no 1 has the 5 wires anywhere on the relay board

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Yes, the original wiring diagrams you are looking at are for using a the DB37 harness.  You only have 1 ground, 1 switched power, and one constant power to the relay board.  The relay harness gets the power it needs to feed the ECU from the relay board.  Make sure you run your sensor wires and sensor returns back to the relay board in the appropriate spots.  The relay board really eliminates a lot of gray area as far as the wiring goes.  Good luck.  I'm still fighting a misfire with my install.  Not sure what it is yet but hopefully yours will fire up and run right after a little tinkering.  Good luck.

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Ok, This is exactly how i have my board wired in minus the tach signal which has been giving me fits from day one, its just confusing to me because the ground and signal wire run in the same sheath and their twisted and foil protected and all that good stuff. 

My questions/ can i run my sensor returns as shown in this diagram or does each sensor need to have its own separate return ground? Also, am i correct in thinking that the white tach signal is the only wire that gets connected to terminal 15 on the relay board? If so what do i do with the black wire that runs along side it? I have the black wire grounded through the distributor.

my280zxt_relay_wiring_zpsd290fdc4.gif

 

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Run your sensor returns as shown in the diagram. These returns are grounded through the relay board. As long as your relay board is grounded well, you shouldn't have any trouble.

Edited by OhBilly
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