Check the gauge and power fuses first, then identify the failed component with a continuity test or jumper wire. Possible causes include a failed ignition-switch contact or the main electronic control relay module.
A 2000 F-150 owner reported that the power door locks would not work from either switch, although both locks moved slightly when a switch was operated, and asked whether the relay or both switches had failed. One reply suggested the relay, and another described using silicone grease on the actuators of a different vehicle. The expert recommended checking the gauge and power fuses, then using continuity or jumper testing to identify the failed component, noting possible failure of the ignition-switch contact or main electronic control relay module.
