Hy nickcs2004, as has been said the violet wire was used to activate a key operated starter which the V8 powered and Hydramatic equipped trucks had in these years. The resistor bypass terminal usually carried a pink wire which went from the other small terminal on the solenoid to the coil side of the ballast resistor. On the 12 volt foot starters a small terminal was installed on the contact housing, a wire from this terminal went up to the coil side of the ballast resistor, the only time power goes out from either of the resistor bypass terminals I described was when the engine was being crancked by the starter, hope that helps
