Electrical Microsquirt harness help

Grisortor

Member
Oct 11, 2019
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Hey dudes I bought a microsquirt with a jumper harness recently hoping to get my new to me fox running and to buy some wiggle room to build some power as paychecks allow. Long story short the previous owner did a number on the old harness (cut sensor grounds, wires twisted together, the whole 9) so I decided to pick up a microsquirt specific harness and make my own.

Has anyone around here done anything similar in the past? I would really appreciate any sort of information yall have to give.

As far as specific questions go, on the jumper harness that came with the ms unit there is a 330 resistor jumped from pin 57 to pin 36 on the 60 pin that plugs into the old harness. Why is that there and should I replicate it on my home built harness?
 
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General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
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Haha. I actually have not messed with anything microsquirt (or any other squirts) just yet. It's nice to know that I seem more knowledgeable than I am, though. :D
Well you and that 'other guy' look so much alike on here I get the two of you confused
I do live in the 'state of confusion ' literally.
 

a91what

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Mod Dude
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The only reason i can see them doing that is for using the 12V+ input on the MS as a launch control input. FWIW i would not do it this way, instead use the nitrous input pin for the AC input from pin #10 of the factory harness and use the flex input on pin 30 for the clutch input that is pulled to signal ground.

What is the end goal and what options do you want/need in the harness. Will the car have AC? do you want it to control an electric fan? these are the things i need to know.

I have all the diagrams for both, so if you need anything i can help with that. when your done i also do tuning if needed.
 

Grisortor

Member
Oct 11, 2019
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In the near future the plan is to run an electric fan and water pump to cut down on parasitic drag since the older 302s are kind of anaemic. I'm gonna pull the ac system in favor of an idler as well.

My thought was maybe the resistor was acting as a signal booster since its soldered into the spout signal wire with the warm up led from the ms unit.

Thanks for all the quick replies I forgot how complex early 90s electrical can be.
 

a91what

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Mod Dude
Apr 6, 2011
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In the near future the plan is to run an electric fan and water pump to cut down on parasitic drag since the older 302s are kind of anaemic. I'm gonna pull the ac system in favor of an idler as well.

My thought was maybe the resistor was acting as a signal booster since its soldered into the spout signal wire with the warm up led from the ms unit.

Thanks for all the quick replies I forgot how complex early 90s electrical can be.
you said pin 57 and 30, I assumed on the 60pin harness.

The microsquirt uses the WLED output to fire the TFI, the pullup resistor is there for a 12v signal.

my apologies
 

Grisortor

Member
Oct 11, 2019
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Utah
No worries thanks a ton for the info. My grasp on the english language was kinda shot after getting of a 12 hour shift and spending 3 hours pulling the harness and getting all the plastic and tape stripped off.

Should it be alright to run the 330 resistor that came with the jumper harness or should I run a 1k like the 2nd manual is saying? (Never thought to look up another manual but I'm glad I stumbled across it.)
 
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