garybwheels

Thanks Fairtax4me for the information. Will keep this in mind if I have to do further debug. I started to have doubts about the failure when jumper was installed to bypass the clutch safety switch, so reinstalled it. Have been driving a couple days with no failures to start. I plan to leave it in place for a good couple of weeks of solid use. If there are no failures then I'll remove and reconnect what I suspect is a faulty clutch safety switch. I hope at that point to have some failures again. In that case I'll just replace the switch. Otherwise, I will do debug as you suggest.

Yes, the clutch pedal switch. That's what I was calling it (actually clutch safety switch, but some guy at an auto parts store said it was called the Neutral safety switch). Anyway, yes it has cruise control. The lower switch on the pedal is for the cruise disable, if one steps on the clutch. The upper switch is used for the starting circuit. I jumped it with some 16G wire that I crimped on a male spade connector on each end, and plugged into the upper connector, once I unplugged it from the switch. I do have a voltmeter and can try some measurements while it's failing. Where is the interlock relay located? thanks for the ideas,

Powersr8810 sent me a private note and said the issue just went away - he never did anything specifically to fix. Well, I'm not so lucky. Any ideas appreciated, thanks

It's 2 years later, and I don't know if this guy solved it (I sent him a PM to ask), but I am having a very similar problem with my 2005 Subaru Legacy GT, manual transmission. Intermittently will not crank when the key is turned. If it fails too many times in a row, then I get CEL and blinking cruise light. My AP gives code P1518 (starter switch low input). If I back off on the clutch pedal by 1" while holding key to start position then it cranks and starts (sometimes). I was suspecting the neutral safety switch and shorted it out with a jumper - thought that fixed it (indicating a bad switch), but then it failed again to start, with the jumper in place. :-( That stumped me. Back to ground zero. any clues? thanks, Gary