1010 gas crawler electrical question

[Gclark]

I am replacing the wiring harness and noticed there is a diode on the back of the ignition switch between the “L” terminal and the switch case (ground).

Does anybody know why this diode would be there? Just want to be sure I am not hooking something up wrong.

Thanks.

[Hurlbutt]

I cant say I actually know why it was included but I suspect it is associated with switching of the power for circuitry which has a coil involved. The diode is often used to shunt “ringing” of a circuit when the power is turned off in electronics. The collapse of the magnetic field will induce high voltage and burn contacts by arching or electronic components by exceeding their capability. In the ignition system, the points are protected similarly by the condenser which absorbs the voltage spike to keep the points from arching.

[Gclark]

Thanks for the reply.

I know a diode is sort of a one way valve for electricity. I have seen one used to prevent an alternator from backfeeding the coil after the ignition switch is turned off.

Just not sure why it would be used to connect the L terminal to ground in this case. Maybe it is to shunt that terminal to ground under certain conditions as you suggested.