Engine block heater

I have a 2002 Silverado with an engine block heater that does not work all the time. Or least in temps above certain temps. Does anybody know how I can test the engine block heater?

Maybe it does not work at warmer temperatures by design. You don’t need it when it is warmer. That would be a feature not a problem.

Can you be more specific?

A block heater is a simply heating element in a case that’s installed in a freeze plug hole into the water jacket and hests when plugged in. Perhaps it isn’t putting out sufficient heat to be having a measurable impact above certain temps, just like there’s a big difference between 20 degrees out and 80 degrees out but not much difference between 70 degrees out and 80 degrees out.

What exactly are the symptoms that you’re struggling with?

When you suspect the block heater isn’t working, disconnect the heater from the power and either measure the resistance across the prongs of the plug with an ohm meter or use a battery powered continuity test light. If the ohm meter reads infinite resistance, or the continuity tester does not light, then the circuit to the heating coil of the block heater is open or the heating coil is broken. If ohm meter shows a low resistance or the continuity tester lights, the block heater is o.k. If the block heater at the warm temperature shows no continuity, then test it when the temperature is cold. If the ohm meter shows that there is low resistance or the continuity tester lights, then the block heater is o.k. and has an internal thermostat. If you get infinite resistance or the test light shows no continuity, then the block heater is defective.