got some megasquirt wiring questions

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91boostedb20
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got some megasquirt wiring questions

Post by 91boostedb20 »

Hi everyone,
After successfully building the ms2 pcb3 a little while back im now moving onto the wiring. I bought the diyautotune 8' wiring harness. I will be making my own fuse box/relay block for under the dash. I was looking over the wiring harness yesterday and just have a few questions to help me clear up some things.

1. For the dizzy wiring, the diyautotune harness has a black and a white wire with a noise insulator around it. I see on diyautotune's website to hook up the white wire on the harness(goes to pin 24) to the white wire on the dizzy. Plus it looks like I need to add 12v to that wire?(I already installed the resistor inside the ms2). Can this be the same 12v source as the dizzy black/white wire gets? So does the leftover black wire on the harness(goes to pin 1) go to the black ground on the dizzy then? I thought I read somewhere that pins 1,2, 7-19 all ground inside the ms2.

2. As for the sensor grounds, looking at the external wiring diagram for the diyautotune harness, all the sensor grounds go back to pin 7. Can I run all the sensor grounds to that pin or will it overload it? It will only have the iat, clt, wideband, and tps. Or should I add ground wires to the db37 connector at pins 8, 9, and 10 so each sensor has its own wire for ground?

I think thats all for now. I greatly appreciate the help.
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supakat
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Re: got some megasquirt wiring questions

Post by supakat »

I moved the thread to DIY's section. Matt may be on shortly but in the meantime, you can contact them if you are pressed for time and report back your solution here.

Thanks.

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Matt Cramer
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Re: got some megasquirt wiring questions

Post by Matt Cramer »

91boostedb20 wrote: 1. For the dizzy wiring, the diyautotune harness has a black and a white wire with a noise insulator around it. I see on diyautotune's website to hook up the white wire on the harness(goes to pin 24) to the white wire on the dizzy.
Yes. And you can use the black wire in the shield for the sensor ground.
Plus it looks like I need to add 12v to that wire?(I already installed the resistor inside the ms2).
The resistor will do tnos, so there's no need for adding it a second time.
I thought I read somewhere that pins 1,2, 7-19 all ground inside the ms2.
This is correct.
As for the sensor grounds, looking at the external wiring diagram for the diyautotune harness, all the sensor grounds go back to pin 7. Can I run all the sensor grounds to that pin or will it overload it? It will only have the iat, clt, wideband, and tps. Or should I add ground wires to the db37 connector at pins 8, 9, and 10 so each sensor has its own wire for ground?

I think thats all for now. I greatly appreciate the help.
The pins are rated for 5 amps in our harness. The sensors are going to be drawing in the milliamp range; you're safe there.

Do not run a wideband power ground to the MS - they're used for the heater and carry a lot more current.
Matt at DIYAutoTune.com - Megasquirt ECUs, fuel injectors, wideband O2 sensor systems, and more
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91boostedb20
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Re: got some megasquirt wiring questions

Post by 91boostedb20 »

So the wideband controller shouldnt be grounded through the megasquirt like the diagram shows? I thought the megasquirt and the wideband were suppose to ground together for a more accurate reading. I will have it powered from its own fused circuit.

As for the dizzy wiring, I dont need to supply the 12v to the white wire then? I didnt really understand the answer you gave me.

Also the dizzy has 2 black wires, which one of the black wires dont I use?

Sorry for all the questions. Thanks.
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Matt Cramer
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Re: got some megasquirt wiring questions

Post by Matt Cramer »

91boostedb20 wrote:So the wideband controller shouldnt be grounded through the megasquirt like the diagram shows? I thought the megasquirt and the wideband were suppose to ground together for a more accurate reading. I will have it powered from its own fused circuit.
Normally, the MegaSquirt ground and the wideband ground should be at the same location - such as grounding both to the cylinder head. Unless the wideband has a separate analog ground, do not ground it to the MegaSquirt itself.
As for the dizzy wiring, I dont need to supply the 12v to the white wire then?
Right - you do not.
Also the dizzy has 2 black wires, which one of the black wires dont I use?
If you're not sure which is ground and which is the second trigger, just ground both of them.
Matt at DIYAutoTune.com - Megasquirt ECUs, fuel injectors, wideband O2 sensor systems, and more
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91boostedb20
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Posts: 45
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Re: got some megasquirt wiring questions

Post by 91boostedb20 »

Thanks for clearing all that up for me. Looks like im all set to go now.
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