HSI or Cooktop Light Always On

When you have an HSI (Hot Surface Indicator) light or a “Pilot” light that is always on, it’s generally going to be either an infinite switch, or an element that is faulty.

Review the diagram for the unit you’re working on. Determine where the light is getting its line and neutral. Then start disconnecting those wires, one by one. When the light goes off, you’ve found your culprit.

In the diagram below, we have traced out how the Cooktop Light is getting line and neutral. It’s through the infinite switch. When the switch is turned and engaged, the infinite switch closes the contact and supplies Line voltage to the Cooktop On light. When the switch is closed, then it will cut off.

When you have a Cooktop light that will not turn off, and you have, say, 4 infinite switches, you simply disconnect the infinite switch wire connectors one by one until the light goes off.

And let’s take a look at another diagram, this one for the surface indicator light. This diagram is a bit further out, but you can see that the RR surface switch is closed, sending line voltage through to the Surface Indicator light.