How to Troubleshoot & Replace Whirlpool AP6009180 / WP4173175 Light Bulb

Screwing in the light bulb was not a problem. Finding the bulb was. Manufacturer's cost was exorbitant for a bulb. Good news was APP had the bulb at lesser cost. Ordered on Sunday, shipped on Monday, and delivered before noon on Tuesday. Service cannot be beat! 

Change light bulb with new. 

Ordered a new one and replaced it. 

Consulted You Tube for trouble shooting. I ordered the part without being totally sure the part would fix the problem, but it did. I decided to replace one of the oven lights that had failed as well. Kind of an expensive light bulb, but sure helped to illuminate the oven better with two bulbs rather than just one. 

After looking at different stores, hardware stores, unable to find replacement bulb. I found the bulb on line here at AppliancePartsPros.com. I had to use a cloth over a pair of pliers to unscrew the bulb cover(appeared to have been cooked on or simply screwed on too tight in the first place), then I could unscrew the bulb. After I received the new bulb, I screwed it in, light went on, replaced the cover, all is great again. 

Replaced. 

With multimeter I had my son test elements, interior temperature sensor and thermal fuse on back of unit. Blown thermal fuse was replaced and problem solved. 

Replaced the thermocouple 

Replaced it 

Inserted the bulb.