View Full Version : MC-4 Yellow Kill Wire Problem

05-12-2008, 01:10 PM

Anyone, MSD techs....

I am using an MC-4 in with an electric solenoid actuated air shifter, with the ignition programed in standard kill mode (kill every shift). I have the system wired exactly as in the wiring diagram which came with the ignition, with the yellow wire branching from the line which goes to the solenoid receiving 12V from the handlebar push button, which then goes on to the solenoid and finally to ground.

The problem is the kill seems to be intermittent, and when it does work, I have to hold the shift button down for a relatively long time (3/4 -1 sec.) for the kill, and shift to take place. In the manual it states that the kill period will begin when the 12V signal is received at the yellow wire. I have tested the shift button ( a momentary, which sends 12V. as long as I press it), and sure enough, a signal is received at the yellow wire.

Any ideas?


05-23-2008, 07:34 AM
After testing, it is clear that the MC-4 box is receiving the kill signal, it just doesn't kill the engine most of the time. It will kill it perhaps 1 out of every 5 attempts, which is useful.
Internal electronics or logic failure.

Thanks for responding MSD. The MC4 only cost me 750+ dollars.
You guy's are the greatest!

05-28-2008, 09:46 AM
When checking for 12 volts did you use a test light or a multi meter? If there is 12 volts at the yellow wire every time the button is pushed the unit should kill. One thing you can check is in the software make sure it is set up for kill mode manual and kill source is wire. Also remove the yellow wire for the button and go to the 12 volt side of the battery with the bike running and it should kill every time you hit 12 volts if not there could be something wrong with the unit.

Thank you
MSD Powersports.

05-30-2008, 09:52 AM
MSD thanks for responding.

The button is a direct 12 v source, as confirmed by VOM.
The software is set for killwire and manual. With laptop connected, the software indicates the kill is active when the button is pushed, but the engine does not die. I suppose this would indicate a problem with the box.