MX-6 & 626 2.5L
WARNING: This page is about a different car, the 1995 Mazda MX-6 and 1995 Mazda 626. However, it is still accessible from the selected car via links, so may be relevant.
Remove distributor. Unplug distributor 3-wire connector. Using an analog voltmeter (or oscillo-scope), connect negative lead to distributor ground (distributor body or Black/Red wire). With voltmeter positive lead, backprobe Pink wire. Turn ignition on and rotate distributor shaft. Voltmeter should indicate one voltage pulse (5 volts) per revolution. Replace distributor if necessary.