Error Code 3

My spedometer is inop and the milage indicator flashes error code 3 when it works at all. Does anyone know which electrical part is bad?

Im sorry, I cant answer you, I dont know, but can you tell me how is it possible to show error codes without any code reader. Chrysler blink it trough LED on dash, when you are turning keys, GM need to connect A and B pin on ALDL and blink it too, how fords have this feature? Thx

Now...all the gauges work, the things that don't work are:
Cruise Control
Speedo
Odometer
Radio will not hold station
Interior lighting (if you turn the radio on, put the bulb in the dome light and turn it on, the radio will go dark, interior light still does not work)

It acts like it is 'hunting' for ground....but where, any ideas?

Answer: Your car will flash an error 3 when you have a problem with
the brake system. Therefore you need to scan the ABS (brake system)
for fault codes.