1996 Toyota Tacoma starter clicking

There are several simple things you can check:
1. Remove & clean the battery cables & battery terminals. If there is any corrosion or discoloration of the strands of the cables at the cable ends - replace the cables. Corrosion will impede current flow. Any corrosion on the battery terminals will do the same. Insufficient flow will cause the clicking.
2. Test for a full battery. The starter requires a whole heck of a lot of juice and a discharged battery won't have the juice to turn the stater, but will just activate the solenoid & cause clicking.
3. The starter solenoid (either on the fender or on the starter) may be bad. Try running a jumper cable
directly to the power terminal (the big terminal) on the starter & see if that turns the starter. If so, replace the solenoid. Also check the ground cable at the block. A poor or loose connection will cause clicking too.

Starter solenoid or key switch.

I had to guess at the engine size. If your engine uses the little silver Nippendenso starter, and you're hearing a single, rather loud clunk each time you turn the ignition switch to "crank", the contacts are burned away in the starter solenoid. Most people just replace the entire starter, but the contacts are available from a starter rebuilder shop for about three bucks. Chryslers use the same solenoid. There's one "battery" contact that is used on all of these starters. For the second contact, there's three versions, and there's no way to know which one you need until you take it apart.

There's also three versions of plunger with the contact disc that were used. It's a good idea to replace that too. Two of them were used on the Chrysler starters. The third one used with Toyotas is only available through the dealer, of course for a much higher cost.

This problem always starts out as an intermittent problem. If you cycle the ignition switch enough times, the starter will work eventually. This will get worse over a period of weeks or months if it is ignored.