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Old 03-18-2010, 02:51 AM   #1
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Default Another Launch Control Q

Alright, so I searched and found a lot of good information, but I still can't get launch control to work. When I turn it on, it never deactivates; the indicator in MLV says "LAUNCH" whether the clutch is pressed or not.

I disconnected the neutral safety switch, no change. My clutch input comes on JS7, and I have the pin on the MS2 daughterboard jumpered according to the megamanual.

I know my circuitry is correct - I tested it in the car, and the MS2 daughterboard sees 4.7V without pressing the pedal and .6V with the pedal pressed. So, either the MS2 is kinda broken, or it's something in the settings.

Anyone have any ideas / settings that work for this?
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Old 03-18-2010, 10:06 AM   #2
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I ran into the same problem on my 95 using the Clutch wiring found in the wiring diagram. I hooked a DVM up to the switch via harness and depressed the clutch pedal to find a connection made, but had like 260 ohms resistance. Tapping the brake pedal reduced the resistance to around 100 ohms.

My best guess was something to do with cruise control and instead of messing with it just put a micro switch in my center console that I can press and hold. Sorry I can't be of more help but it wasn't worth the trouble to fix when I could just use the switch.
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Old 03-18-2010, 04:02 PM   #3
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To my way of thinking, whatever resistances are in the circuit shouldn't matter as long as the processor sees the correct voltages. I'm already getting either .6V or 4.7V at JP4 on the MS2 daughterboard, so I don't think a separate switch to ground would help at all.

I saw something on the megasquirt hardware mods page about removing R10 on the mainboard and wiring something up to there, and I'm not sure I did that. I only saw this mentioned in one spot though, and I can't find it again. I'll crack it open later today and look at what I built in there, hopefully that helps. (that's for table switching control)

If this whole LC thing ends up being too much of a headache I'll just scrap it, I don't do drag and it'd mostly be a fun party trick / a little help for autox.

Last edited by mrpurplepenguin; 03-18-2010 at 04:30 PM.
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Old 03-18-2010, 04:25 PM   #4
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I just hooked up my launch control yesterday and played with it and I certainly was stumped by this same thing at first.

The clutch switch doesn't make any difference unless you're in gear. Put it in first and get moving slowly so you can let off the clutch and look at the screen. The green Launch On light will go out. Perhaps this would work without the car running as well, I haven't tried it that way though.

Use your TPS to activate the LC at about 1/3 or so of your max throttle input. You may want more or less throttle to activate it, but I find this is the perfect point to not get in the way of my daily driving and my girlfriend isn't going to accidentally activate it and roast tire when she's driving the car.

It takes practice and tuning to get it right, but I think i've got mine dialed in just about right. I get a fair amount of wheel spin (and wheel hop, ugh) on cold tires but i'm betting on a warm day at an autox i'll be fine. Might activate it at a slightly lower RPM but we'll see. I have it kicking in at 2500 right now I think.
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Old 03-23-2010, 10:16 AM   #5
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Quote:
Originally Posted by wayne_curr View Post
I just hooked up my launch control yesterday and played with it and I certainly was stumped by this same thing at first.

The clutch switch doesn't make any difference unless you're in gear. Put it in first and get moving slowly so you can let off the clutch and look at the screen. The green Launch On light will go out. Perhaps this would work without the car running as well, I haven't tried it that way though.
Sorry I'm late back to the party, but ?? !! ?? !! Wut year is your car?
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Old 03-23-2010, 05:07 PM   #6
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wayne, the clutch switch should function all the time, in gear or not.

I tried rewiring the clutch input from JS7 over to JS11, no change. I'm pretty sure there's no problem with the hardware, so it's gotta be something in software. Guess I'll try reflashing the firmware once I can get back to a computer running XP, 64 bit Vista doesn't play nice with the files.

But yeah, just to recap- MS2 thinks launch is engaged all the time, clutch pressed or not. Voltages getting to the chip are good; 4.7V with no clutch, .6V with clutch. MS2extra running 2.1.1beta. Any ideas?
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