Toyota Repair: thermo time switch, timer switch, time switch

Question
I have a 1988 4runner and I need to know where the thermo time switch is located on the V6. What indications would lead me to suspect it needed to be replaced?

Answer
What? The coolant timer switch only operates the cooling system fan.
Do you mean the thermostat? Replace that about every 4 years, the radiator pressure caps. Flush the coolant every other year.

If the thermostat sticks it can lead to overheating, or under-cooling. Most noteably in the winter on descent thermostats that stick "open" to let coolanyt flow through unblocked. The engine & hence the heater can take along time to come up to temperature.