I have a Quantum Competition 2 I need the number for the polarized Schottky diode and is this a large can diode or a small one. I just use it in oval racing do I need to install one on the speed control and I am having a glitch would and bad diode cause this problem. Or do I need a diode from the negative to the positive?

you don't need one. yes a bad one would cause a glitch

i use this speedo and never used a diode. i dont think you need one either

Do you think I need a diode from the negative to the positive so I will not get glitch
? Thanks for all the help!!!!

i never use a diode. just make sure you use 3 capacitors on the motor.