I have a 1978 Loadstar 1700 in excellent condition but the ignition switch keeps failing in Start mode. This is the 4th switch in a year. It works for a month or two then fails to engage the starter. Each time it fails the switch is found to be bad. I finally opened the last switch up and the only thing I noticed was the contact had minor pitting and some carbon deposits. Hard to believe that too much current could disable these contacts and not burn a wire up. But the ohmmeter showed no continuity when in start position though it did when it was new. The internal contacts are heavy duty. All accessories work and truck can be started with a remote switch connected between battery and solenoid. No sign of melting or wear on switch or wiring. Bought one switch from Autozone, and two from NAPA. They also tested the switch to verify it failed. All wiring in cab looks like new. No shorts found in the wiring. The solenoid was replaced after switch 2 failed so it isn't that. All the ignition switch does on this age truck is connect 12v to the solenoid signal terminal when key is turned to start. There are no safety switches. Wires inside the engine bay are in a harness, so no chance for shorting. There are no signs of shorting such as smell, hot wires, blown fuses, and it immediately stars by inserting a new switch. I cant think of what it could be. I ran a separate push button switch to the dash, ran it to the battery, directly to the solenoid and installed a 30 amp fuse and that has worked fine but not long enough to be 100% confident. Anyone else seen a problem like that? The Start line is only engaged a few seconds during startup, so the switch really fails quickly when you consider it fails after 20 or so starts.