big-phil Posted October 6, 2007 Share Posted October 6, 2007 I just got megasquirt to work my fan. I thought I wired it up wrong? I had the output going to the + of my relay. Then after some time I thought what the hell I'll hook it up to the ground? BOOM it works! Still can't get my tach to work, but now I'm wiring up a "shift light" to out put 2. I tryed it with my fan output and it works great!! next I'm going to try to wire the megasquirt up to tell my meth pump when to come on. I'm going to try a tach adapter for the tack?? I guess?? *sorry I can't edit the title "SWITCH" was the word I was looking for* Quote Link to comment Share on other sites More sharing options...
olie05 Posted October 7, 2007 Share Posted October 7, 2007 Do you have an MSD? If not you should be able to run your tach off the negative side of the coil. also, yes megasquirt switches ground on everything. Thats why there are like 6 ground wires on the pigtail. Quote Link to comment Share on other sites More sharing options...
big-phil Posted October 7, 2007 Author Share Posted October 7, 2007 Do you have an MSD? If not you should be able to run your tach off the negative side of the coil. also, yes megasquirt switches ground on everything. Thats why there are like 6 ground wires on the pigtail. when I had my Accell super coil the tach worked off the neg side of the coil. Now I have a Mallory and now the tach jumps like crazy from the neg side of coil, most of the time it just sits at zero doing nothing. Quote Link to comment Share on other sites More sharing options...
mario_82_ZXT Posted October 7, 2007 Share Posted October 7, 2007 Add a resistor from 6-10k ohm on the wire that goes to the tach. Hopefully it isn't damaged (I've heard of that happening which is why you need the resistor). Also, MS grounds all it's outputs, if it were to feed 12v I have a feeling it wouldn't be able to drive much due to the small traces. I need to do the electric fan mod on mine... Mario Quote Link to comment Share on other sites More sharing options...
big-phil Posted October 7, 2007 Author Share Posted October 7, 2007 Add a resistor from 6-10k ohm on the wire that goes to the tach. Hopefully it isn't damaged (I've heard of that happening which is why you need the resistor). Also, MS grounds all it's outputs, if it were to feed 12v I have a feeling it wouldn't be able to drive much due to the small traces. I need to do the electric fan mod on mine... Mario Thanks, I'll run to Radio Shack tomorrow for maybe a resistor trimpot type thing. I just drove the car and the fan is fanning, the green l.e.d. is on with the meth, and I put a red l.e.d. that comes on at 5500rpm (when power starts to fall on the stock cam:icon50:) I now feel like I'm starting to use megasquirt for what it was made for! Quote Link to comment Share on other sites More sharing options...
gearheadstik Posted October 7, 2007 Share Posted October 7, 2007 I had to use a 75-77 tach with the oem tach resistor, but then I'm using EDIS. The 78 tachs will not work with my setup. What year is yours or you just trying to get a aftermarket one to work? Quote Link to comment Share on other sites More sharing options...
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