1995 Toyota Camry Temp gauge goes to full hot

check the engine coolant temperature gauge (on left OR right side of engine, depending on engine size). also check the engine coolant temperature sensor (on left OR right side of engine, depending on engine size) .

I replaced the engine coolant temp switch also. Removed thermostat to verify it is not thermostat, and it still goes to full hot. According to manual, the power for the coolant temp switch comes from or goes thru the engine control module.

if you are certain the gauge is reading inaccurately and the sending unit has already been replaced then it is most likely the gauge itself at fault.

FIG. 2

how can I rule out a blown head gasket?

one easy way to check for a cracked head gasket is to let the engine cool completely. then remove the radiator cap. ensure noone is near radiator, then start the engine. rev the engine up to 3 or 4k RPM. if coolant shoots out of the radiator cap opening then you have a faulty head gasket or faulty head. another way is to simply have it pressure tested at a shop.

Thank you so much, I will check both tomorrow