How to Troubleshoot Halogen Lights Under Cabinets

Clean the lights. Turn the lights off and allow them to cool. Wipe with a soft, damp cloth and allow to dry completely before you turn the lights on again. A build-up of grease, dirt or anything else, such as flour in a kitchen, on the lights could cause them to look dimmer.

Examine the wiring. Look for breaks in the wiring or nicks in the insulation. Loose wiring or broken wires could cause lights to flicker or to go out unexpectedly.

Test the voltage coming from the transformer with the voltage meter. Halogen lights that use a transformer need at least 12 volts coming from the transformer. Lower voltage than this can lead to dim lights, while voltage fluctuations can cause lights to burn out too soon. Replace the transformer if you find problems.