Ignition wiring sanity check

[vex]

Originally Posted by NoDOHC

TTL means Transistor - Transistor Logic. This is almost always referring to a 5V signal.

There is no reason that I can think of that you should power your coils all the time (feed the Battery + with a switched source). The secondary ground should be connected as close to the spark plug as possible (this is the return path for the spark), the battery ground should be connected to a good ground point or the battery negative

So if I can, mate the secondary ground to the engine itself? Got it. Battery ground can be mated to a good chassis ground?

Will the Platinum Sport ECU permit driving a coil at 5VDC instead of 12? (adjusting the pullup to 5V instead of 12V)? If so, you can invert the ignition output, drive the high at 5V and connect the low to the ignition output.

No... it can't do ignition pull up like that... but I could do a DPO at 5v, or hook up the 5v sensor source to them which might work out easier.

You can also ground the negative side and leave the output non-inverted (it will go high to energize the coil, fall to fire).

There are basically 2 things that you need to know. First, are the TTL inputs capable of accepting 12V (nominal - actually about 14V)? If not and second, can your ECU drive to 5V instead of 12V?

I'm still waiting to hear back from 034 for the proper wiring schematic... As for the second I think I covered that pretty well.