All of a sudden all the lights inside the dash board stopped working?

Based on the symptoms you described, it's possible that you are facing an issue with the illumination circuit in your 1997 Ford Taurus. When both the dash lights and tail lights stop working at the same time, it indicates a common problem affecting the lighting system.

Here are some potential causes to investigate:

Blown Fuse: The first thing to check is the fuse box. There might be a blown fuse that controls the illumination circuit for the dash lights and tail lights. Look for a fuse labeled "Illumination, " "Instrument Panel, " or "Tail Lights" in the fuse box, and inspect it for any signs of damage or breakage. If the fuse is blown, replace it with a new one of the same amperage rating and check if the lights start working again.

Faulty Headlight Switch: The headlight switch controls the operation of the headlights, tail lights, and dash lights. A faulty headlight switch can cause issues with the illumination circuit. Try toggling the headlight switch on and off to see if the lights respond. If there's no change, the headlight switch may need replacement.

Faulty Dimmer Switch: The dimmer switch controls the brightness of the dash lights. If the dash lights stopped working suddenly, the dimmer switch might be the culprit. Test the dimmer switch to see if it affects the illumination of the dash lights.

Wiring Issue: There might be a wiring problem, such as a loose or corroded connector or a damaged wire, in the lighting circuit that is causing the lights to stop working.

Bulb Failure: Although it's unlikely that all dash lights and tail lights would fail at the same time due to bulb failure, it's still worth checking the bulbs to ensure they are not burnt out.

Body Control Module (BCM) Issue: The BCM is responsible for controlling various electrical functions in the vehicle, including the illumination circuit. If the BCM is malfunctioning, it may affect the lights' operation.

Check for power on fuses 14 and 31, both 5 amps fuses inside the car. If both have 12 volts on both sides, there may be a lamp outage module in the left rear side of the trunk. I need to know if you have that option.

Check under the hood for power on both sides of the tail lamps fuse. It's a 15 amp fuse. If you have it there, we have to go to the head light switch next. On that switch, check for 12 volts on the purple wire. It should be there all the time. Next, check for 12 volts on the brown wire. It should be there when the switch is turned to the tail lights or head lights position.