Jan 22, 2012

Megasquirt 3 Wiring Help LM7 / LS1 / LS

Well its been a while since I posted last. I’m going to make it a priority to post more frequently now that things are speeding back up on the project. I’ve been making steady progress but just had things slow down a lot when it came to getting the motor running on the Megasquirt 3 and assembling the Megasquirt 3.

Here are some links that should help you wire up a LM7 (LS 5.3L) or LS series motor to a MS3 with MS3X (Megasquirt 3 with Expansion for sequential fuel injection).

Step 1) Decide which manual is correct for your engine (24x reluctor engine or 58x reluctor engine)



Misc Info on LS engines very helpful site


Step 2) Run all the correct wires to your engine. If you buy the DIYAutoTune harness it comes with the wires pre labeled def worth the ~$160 bucks.

Step 3) When it comes to wiring up your ignition if you want to use the parent (7 or 8pin I forget plug) for cleanness it connects to all 4 ignition coils. There are one of these parent plugs (on top of the valve cover) on each side of the motor and each one runs to 4 ignition coils.  Look at this diagram for help in wiring those up.

I cant remember of the top of the head which ones I had to use.

Even Ignition Coil Diagram:


Odd Ignition Coil Diagram


That should get you going in the right direction. Here is a pic of my motor fully wired up on the stand. It’s got a fuel pump and is pretty much ready to start.


My next post will talk about how I built a little Arduino (microcontroller) that controls relays over bluetooth. This will allow me to remove start the engine and control relays from a bluetooth device like a phone or tablet. Thanks!


  1. It's looking good man. I like the way it is coming together. Do you have any update pictures since January??

  2. Yeah I will post some new pictures soon. I've been lazy about the blog this year and I need to write a bunch of posts to bring it up to speed.

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  4. Sup Pat!

    I'll email you here in 5 minutes, hopefully we can get your issues figured out.