I have paid the mechanic twice to resolve a problem that keeps occurring, albeit it is inconsistently manifested: I turn the key and nothing happens. No noise of any kind. It is as if the battery was totally dead. But it is not. All of the electric systems work just fine.
Despite going against what I felt the problem was, the mechanic replaced the battery. Still had the problem a couple days later.
Next time, he bypassed the sensor on the clutch (this is on a '03 Chev S10, red (does that help? 
Seemed to do the trick, for a couple days.
Went back the third time and he replaced the wiring (ignition) harness in the steering column. (It was the next least expensive part to replace). From the beginning he insisted that it COULD be the starter–very costly.
Well, for a couple weeks I thought that did the trick. Again, sometimes it will not start when I first turn the key.
I don’t know if this is related or not, but when it won’t start, I jiggle the shifter, sometimes change gears, and then it starts. Coincidence or related?
I don’t want to spend another $300-400 if it is not necessary, of course.
What else could it be? What else can I do? Am ready for a second opinion. Thought I would start here.
The battery in your vehicle has the side mount battery terminals. Under the red rubber cover for the positive treminal corrosion can form.
Remove both battery terminals and peel back the red rubber cover for the positive terminal to expose the battery connections. If a lot of corrosion is found under this red rubber cover, that’s probably what’s causing the interminent no start problem.
Tester