I just purchased a 1977 300D. The car has some sort of electrical problem whch I can not figure out. The fuses are all fine and I used a volt meter to verify voltage on both sides of the fuses. The following are dead: front parking lights, front turn signals, fog lights, dash lights, radio, heat works only on defrost . Any ideas? Is each one of these an issue to eal with or could thet all be related?

Jeff