Help! Have 98 Protege LX. Brake Lights work but not when Headlights are on.....

Anyone know what problem is? I haven't been messing w/wire's, etc.

 

Have you had any aftermarket accessaries installed, such as auto-start or cruise control? These would tap into the brake switch wires.

 

Were any blubs recently replaced? All kinds of weird stuff happens if a dual element 1157 bulb is put in a socket designed for a single element 1156 bulb and visa-versa. Try removing brake/tail bulbs one at a time and retest to see if this is the case.