the other wires that used to be hooked up to the Alt. are what made the light in the dash work properly. now that you changed to a one wire Alt. you only have the big output wire hooked up to the Alt. so the light in the dash will not work properly now. check to make sure it is charging with a volt meter at the battery, it should be between 13.8 and 14.8 volts. also remember that most one wire Alt. need to have the motor reved up once to get it to start charging. if it is charging the dash light coming on will be ok. if it bothers you, you can reach up under the dash and remove that light bulb from the back of the gauge cluster. also, I would install an aftermarket volt meter gauge in the car to keep check of the charging system.