Going Megasquirt

[Daniel Jost]

No CCCI module, I just "jumpered" the wires at the module connector no need for cutting up the factory harness. I can't remember off hand what color wires are what but im running a raw +12 and ground to them and get a good signal. I can always check for you when I get home.

Dan

 

[22lbChevelle]

Thanks Dan. No need to check for me, I've got mine wired right but for some reason I cant get signals from them. I'm sure it will come to me what I was doing wrong last night.

I've got everything working with the megasquirt except these sensors. Turn on the key and I hear the IAC seat itself, injectors all click, temp gauges read accurate, TPS works... I'm almost there!

 

[Daniel Jost]

Great to hear are you running my MSQ file? I'm wondering if its just not reading right? You are using CNP also right? Are you logging the cam and crank sensor to see if you are getting any input while cranking?

,Dan

 

[22lbChevelle]

Yes I've tried the composite logger and it showed literally nothing. Thats when I busted out my oscilloscope to do some independent testing and I didnt get any signals from the sensors. Its very strange.. And yes I am using LS truck coils.

 

[22lbChevelle]

Oh and yes I will be starting with your MSQ. The settings are way different than what I thought they would be. Not so much the fueling, but the settings like number of squirts per revolution and the cam/crank wheel stuff. I wired the coils and injectors like you did, CylA=Cylinder1, etc

 

[Daniel Jost]

Yes you only need one squirt per revolution (per cylinder). Also you must have a power issue to the sensors. Did you check for +12v and good ground?

Dan

 

[22lbChevelle]

Yea I checked a couple times. Firday night I will have it figured out and hopefully the engine will fire up. I will post video when it does. Thanks for the help.

 

[22lbChevelle]

So Ive taken another look at the cam sensor cap, and it seems like the sensor is actually ground switching. This would explain why I couldnt scope the sensor and expect a voltage pattern.

Is this why you guys have used the optoisolator to wire it in?

 

[Daniel Jost]

Ground switching? Through the output signal you should see either 12v or ground. If you are not getting the square wave you have an issue in the wiring or sensor. Are you saying neither sensor has any output on the signal? If you probe the cam or crank signal return and you crank the engine over by hand what are you seeing for voltages?

Dan

 

[22lbChevelle]

I have verified it multiple ways.

I have triple verified that I have 12v to the gry/red wires, ground to black, and I scoped the blue and green wires on the cam and crank sensor respectively. No voltage came from either sensor while turning by hand and starter.

I also took the cam sensor cap off, plugged in a caspers cam tool and verified it worked. I measured and found that the casper cam tool applies around 7v to the signal wire, so when the cam sensor turns, it forces the signal wire low by switching to ground.

I then took the cam sensor cap and applied power and ground, and measured the resistance between the signal wire and ground, it switches between 10k ohms and zero ohms depending on whether there is something in the cap's hall effect window.

I also unplugged the cam sensor on my dad's stock GN and measured 7v on the signal wire leading to the ECM while the key was on, showing that the ECM applies 7v to the signal wire, and the sensor brings it low by switching to ground.

Turbo1dr, who has a webpage about the "fast start" crank sensor, has some images of scope traces on his webpage. The cam signal appears to be held high until the window opens and then the graph shows the signal being pulled low.

SO, long story short, I am going to wire in the opto circuits tonight and I should be ready to rock and roll.

 

[blackturbocars]

The GM manual has the wrong colors, GM training manual got it right.

CAM sensor wires at the cap:
Red = +12VDC , Blue = Signal , Black = Ground

Wires from CCCI module to Cam sensor connector:
Gray/Red = +12VDC , Blue = Signal , Black = Ground

CRANK sensor:
Dark Green = +12VDC , Gray/Red = Signal , Black = Ground

 

[blackturbocars]

12LBCHEVELLE, you will need a pull up resistor to the sensor's output to get it to go high when the gap is blocked. The sensor output will be low when the "window" is open. The optoisolator allows you to apply +12VDC to the sensor for noise rejection on its input side, and +5VDC to the Megasquirt input on the output side.

Bob

 

[22lbChevelle]

So the crank sensor has the green and gry/red wires swapped?

 

[22lbChevelle]

Dan, when you wired the cam sensor to the MS3X, did you try it with the pullup jumper JP7?

 

[Daniel Jost]

Yes I tried and it didn't work... hence why I used the optoisolated circuit... If you build it the way I sent In the schematic it with work perfect...

Dan

 

[22lbChevelle]

After looking into it, the way you have it wired is perfect. I finished the wiring tonight so tomorrow I will be attempting to start it. Thank you for the tons of help dude!

 

[blackturbocars]

12LBCHEVELLE, I noticed in one of your posts you wired the injectors and coils as "cylinder A = injector 1". That's not per the drawing. A=6, B=5, C=4, D=3, E=2, F=1. You will have problems if it's not connected per the drawing! BUT, if you did wire it the way you stated, you could set the cam sensor so it precedes cylinder 1. Your better off rewiring.

 

[22lbChevelle]

Thanks blackturbocars, that was a typo, I wired them according to the drawing. I have considered rephasing the cam sensor but I figured it would be easier to relate to you guys if I needed help.

 

[Daniel Jost]

Exactly! Hope all goes well tommorrow!

Dan

 

[22lbChevelle]

Update: I still dont have cam or crank signal after wiring them per the drawings. I will disassemble the ms3 again and double check the wiring. I was supposed to wire the cam to the JS10 port on the mainboard correct? I did that and set the cam input to JS10 in the tune.

I did try the Output Test Mode and the LS2 coils work great!