I have a 69 cougar and the gauges lights are not working only the oil light and alternator light are going on all other lights are not going on replace all bulbs circuitboard seem to be in good condition what could it be ignition maybe
Check both grounds in the wiring.
Make sure the knob in the headlight switch is able to control the background lighting. Rheostat (dimmer) could be bad.
Check the fuse for the background lights.