AHS 1,701 #1 Posted 17 hours ago It was running yesterday!! It was running, I shut it off and then went back to restart it and no crank. I pushed it into the garage… took apart the key switch, with 5 pins. Normally. 6 pin on a magnum. I was confused! So, i took out a brand new 103990, but the Run circuit was wrong B + R+ I+ A. On the 94, the Run B+L. So, 116338 ignition switch, are there any other part numbers? I am severely confused!! Share this post Link to post Share on other sites
gwest_ca-(File Mod) 12,503 #2 Posted 14 hours ago The switch in your hand has an I (eye) terminal for battery ignition and the 1994 312 has magneto ignition. The M terminal is required and it connects to the ground terminal in the OFF position. That is what kills the ignition. If you can disconnect the blue wires to the magneto it should run. Do not allow any battery voltage to get to those blue wires. That creates magneto smoke. 2 Share this post Link to post Share on other sites
gwest_ca-(File Mod) 12,503 #3 Posted 6 hours ago The first switch is the original. The 2nd is a more common magneto switch but the wire locations on the switch would need to be changed. The switch function also changes. Share this post Link to post Share on other sites
gwest_ca-(File Mod) 12,503 #4 Posted 6 hours ago I would add a diode to the magneto wire to prevent any stray voltage from getting back to the magneto. With the M terminal connected to the A terminal in the OFF position it could back feed momentarily releasing the magneto smoke. 1 Share this post Link to post Share on other sites
AHS 1,701 #5 Posted 4 hours ago 1 hour ago, gwest_ca said: I would add a diode to the magneto wire to prevent any stray voltage from getting back to the magneto. With the M terminal connected to the A terminal in the OFF position it could back feed momentarily releasing the magneto smoke. I was thinking that. So, my stock ignition, the L kinda has two circuits; lights and regulator. So, im going to switch the L to R on the new switch? It isn’t even in the off position on the 103991. OR (103991) OFF G + M + A. Switching the L to A and adding a diode? Share this post Link to post Share on other sites
gwest_ca-(File Mod) 12,503 #6 Posted 2 hours ago I would switch the R and L, move the ground to the side and add a diode to the mag wire at the engine so both blue wires have protection. We do not know where a spike could come from. 1 Share this post Link to post Share on other sites
953 nut 69,696 #7 Posted 1 hour ago Here is a comparison of the 103990 (battery ignition) and the 103991 (magneto ignition switches) and what WILL happen if you interchange them. Rather than rewiring anything you will be far better off buying the correct switch. 1 Share this post Link to post Share on other sites
AHS 1,701 #8 Posted 36 minutes ago Ok. Why not just wire the key switch as the same on the 90-91 312’s ? I'm open to all ideas. Share this post Link to post Share on other sites
