Hy awk, I sent American Autowire an "E" mail, they got back to me and said that their p/n 30370 does not contain a diode, their suggestion was to disconnect the two wire plug, start the truck and then try to shut the engine off, if it shuts off with the plug disconnected then it needs a diode in the exciter wire to stop the backfeeding, as I suggested in my first post, hope that helps.
