Radio<->Headlight Problem '84 Tercel

I own a 1984 Toyota Tercel and whenever I put on my headlights the radio quits working, not even the tape deck works and I'm not sure what could be the problem. If anyone knows what this is caused by and/or how to fix it please let me know, thx.

Hi,

First of all, is it only the radio/tape deck that stops working?

If your answer is Yes, then I would try to find out which wire that your radio is getting its power source from. I wouldn't assume that it's connected to the right wire unless you actually trace it through.

If there's other things being affected, then it's possible that you have too much of a load on your alternator.

Good luck,

Yes its only my radio/tape deck that doesn't work when i switch the headlights on...also if the headlights are on and my radio is off I get a buzzing sound from the speaker and the radio displays a strange number reading 166.9 or somewhere around that. If I put the radio on when the healights are on the buzzing stops and it displays the radio channel but it doesn't play the sound. I have not tried plugging a cd player into the radio and trying it with the headlights on. I traced the wires from the radio and they all seem to be plugged into the correct places so I'm not quite sure what could be the problem now :/