Model #FEF366ECD, this free standing range operated properly, but the surface indicator light would not illuminate when the right front burner was in use. Without this light, the customer was worried the burner could be accidentally left on and there would be no visual indication other than the placement of the knob. So for safety sake, it was time for a service call.
Most ranges have was is referred to as the surface indicator or pilot light. This is the light or lights that turn one whenever any of the surface units are in use. It is used as visual Que to show the surface unit switch is in the on position. Not to be confused with the hot surface indicator light, that works independently of the control knob. The hot surface light is actuated by the temperature of the element and will remain illuminated as long as the cook top is hot to the touch. The surface indicated light, however, is only one when the control knob is on and will turn off when the burner is turned to the off position.
A quick look at the surface unit wiring diagram shows the right two burners along with their control switches, and all the associated wiring. Each control switch, or infinite switch, has L1 and L2 inputs from the terminal block, and then outputs usually labeled H1 and H2. These are the outputs to the elements themselves and provide the 240vac power used for heating. There is also an output labeled P or pilot which is a 120vac output to the surface indicator light. Units that have only one light will run a wire between each of the infinite switches allowing any one switch to apply voltage to the light.
The trouble shooting process for this repair is pretty simple. Using a meter, check for 120vac with the control knob in the on position from the output of the pilot terminal. If voltage isn't present and the element works properly, the infinite switch is bad. Or if the opposite failure is occurring, the lamp never goes out, simply check the pilot terminal (with the wires disconnected) for 120vac when in the off position. If voltage is present and the element works properly, the infinite switch is bad.
Because the customer knew which switch was not working, I only needed to remove the rear cover and check the switch with my meter. When in the on position, there was no voltage indicating a bad switch. But after I replaced the infinite switch with a new one, the light started working again as it should. Now when the burner is left on, the light glows bright to remind the customer to turn it off.