I have a 2000 Saturn LW. It’s generally been a good car. Approximately 6 months ago it would not start (would not even turn over). Had it towed, starter replaced and things seemed fine. Six weeks later, same thing. Replaced the starter again (supposedly battery was checked both times and fine). Works for another month and wouldn’t start again. However, this time I couldn’t get the key in. They replaced the electrical (ignition?) switch. Worked for another month or so and then wouldn’t crank (as usual, would not turn over at all). Had it towed and the mechanic said the wires weren’t connected well. Now 3 or 4 weeks later, almost happened again, but we did get it started on the third try and drove again to the mechanic. Works for him (of course). Says if it happens again, to move the gear handle as it might be a neutral safety switch (I don’t think this is it as I’m pretty sure I tried that on a prior occasion). Has anyone seen this?
It does seem to have electrical issues as the inside lights for certain periods of time will flicker. It also went through a spell where it would just cut off while going about 65 with the cruise and you hit a hill. The low power light would come on and a couple of others. It took getting a new computer? put in to get that to go away.
When it won’t turn over, have you tried to jump start it? When it won’t turn over, does the starter make at least one click sound? Do the lights and radio work with the blower motor on high?
Are the battery cables and posts clean? How about the grounds to the engine and chassis? Either of these can give you intermittent problems. Then there is the GM Passlock system. It can disable any start.
Most of the problems that could cause this have already been either tested or the part replaced. It sounds like your shop knows what they are doing. Maybe one of the replacement parts has failed or was bad out of the box. Also there could be some unseen wiring problem like a broken splice in the harness or a ground problem. On my Corolla I had a problem one time where battery acid from a leaking battery decanted down a major wiring harness and it ate through a splice midway in the harness, invisible to see until I took the harness apart. Ask your shop this: When it fails to crank, or has a weak crank, have they measured the voltages at both starter terminals during attempted cranking, measured from the terminal to the starter case. What are the voltages they measure?
I took it to the GM dealership and they replaced the wiring between the battery, starter and alternator. So far so good. We’ll see. It’s been ‘fixed’ before and goes between 3-6 weeks and then decides to not start again. It’s been about 3 weeks.