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You say the battery tested good in post #4 then you say that it only showed 11.6 volts. That's not good unless that's what it tested under a load. I'd do what yellowdartdave said and borrow a known good battery from another car and see what it does with it. If the problem is the same with the borrowed battery start testing voltage at the battery through the circuit all the way to the starter while you have somebody else crank it. A bad starter relay will click sometimes but not send power through to the starter. A bad starter can also click and not work. You have to be loosing power somewhere. As a couple other guys said a corroded starter positive cable can have allot of voltage loss. Check all these things and if you have the same (or close) voltage reading from the battery to the starter but it still won't crank over the starter must be bad.

A way to test the voltage drop in a cable is to hook up a voltmeter to each end of it. Positive on one end of the cable and negative on the other. Crank the engine over and the meter will read voltage across the cable and that's how much voltage drop it has.

Oh yeah there's one other part in the circuit that can affect starting. The Neutral switch. It provides a ground to the starter relay. If it's bad that will cause a no crank situation.