the oven light on my kfeg500ess won't turn on when i press the button, i've tried new bulbs.

Diagnosis

This issue on the KitchenAid KFEG500ESS is rarely about the bulb itself, especially since you have already attempted replacements. The primary cause is typically a failure in the electrical continuity between the control board and the bulb socket. Because this model uses a high-heat environment, the brass contact tabs inside the socket often lose their tension or develop carbon buildup (pitting), which prevents the bulb from making a solid electrical connection. Another common culprit is the door switch mechanism. The KFEG500ESS relies on a physical switch that triggers the light when the door opens. If the switch is stuck in the "closed" position or the internal spring has snapped, the control board will not send power to the lighting circuit regardless of whether you press the manual button. You can confirm this by checking if the light fails to trigger both manually and upon opening the door; if both fail, the issue is likely the socket or the wiring harness. If the light works when the door opens but not via the button, the issue lies within the Electronic Control Board (ERB) relay.

How to Fix It

To resolve this, you must first ensure the unit is completely powered down. Turn off the double-pole circuit breaker in your home electrical panel to avoid lethal shock.

1. Remove the oven racks and any liners to clear the workspace.
2. Unscrew the oven light cover lens using a Phillips head screwdriver.
3. Remove the bulb and inspect the center contact tab at the bottom of the socket. If the tab is flattened against the bottom of the housing, use a small insulated screwdriver or a pair of needle-nose pliers to gently pry the tab upward by approximately 2-3 millimeters. This restores the tension needed to touch the base of the bulb.
4. Inspect the socket for "blackening" or charred plastic. If the socket is burnt, you must replace the entire light socket assembly (Part #WPW10151252 or equivalent). Unplug the wire harness from the back of the socket and swap in the new assembly.
5. Locate the door switch assembly located near the oven frame. Press the switch manually with your finger; you should feel a distinct "click." If the switch feels mushy or doesn't move, remove the switch from its bracket and test for continuity using a multimeter. If the circuit remains open when pressed, replace the door switch.
6. Reinstall the bulb, ensuring it is seated firmly against the contact tab, and replace the lens cover.

If That Didn't Work

• Check the wiring harness for "heat crystallization." In the KFEG500ESS, the wires leading to the oven light can become brittle over time due to extreme heat cycles. Inspect the wires for any cracks or exposed copper. If the insulation has failed, the wire may be shorting against the oven chassis, preventing power from reaching the bulb.
• Perform a hard reset of the Electronic Control Board. Turn the breaker off for exactly 10 full minutes. This clears any temporary logic glitches in the ERB that may have disabled the lighting relay.
• Test the socket for voltage. With the oven door open and the range powered on, use a multimeter set to AC Volts to probe the socket contacts. If you see 0V despite the door being open, the failure is upstream, likely a blown internal fuse on the control board or a failed relay.
• Verify the bulb type. Ensure you are using a genuine 40-watt appliance bulb. Using a standard household LED or a bulb with the wrong wattage can sometimes trigger a protective circuit failure in the KitchenAid power module.

Heads Up

• Always use a 40-watt, 120V appliance bulb specifically rated for high heat. Standard bulbs will burst or melt the socket housing.
• Avoid over-tightening the light cover lens; the plastic threads can strip easily, leading to heat leaking into the control area.
• When prying the contact tab upward, do not over-bend it, as the brass can snap, requiring a full socket replacement.
• Periodically wipe the inside of the light lens with a degreaser to prevent grease buildup, which can trap heat and cause the socket to degrade faster.