Ok, first, check in your owners manual and see if the horn and lighter are on the same circuit (ie, they have the same fuse in the fuse box). If they are, then the problem is common between the two, otherwise you have either two problems or one closer the power supply than the fuse box. The relay for your horn will either be somewhere in the engine compartment or in the relay box on the right side of the engine compartment (I have a 96 sunfire and thats where my relay box is). Basically, a relay controls a higher voltage circuit with a lower voltage circuit and acts as a sort of switch. They usually look like small boxes and have 4 contacts. Two contacts are the control contacts and when energized open or close two power contacts. In the case of the horn, the horn button on the steering wheel applies voltage to the control contact (one contact goes to powered cicuit, the other goes to ground) which then shuts the power contact supplying power to the horn, theus allowing it to sound. You can check the horn and if the horn relay is working at the contacts of the horn using a multimeter and jumpers. To ensure proper operation, attach positive battery voltage to one terminal of the horn and ground to the other terminal. This should sound the horn. You can check the relay is working by attaching the multimeter leads to the same terminals you had connected the jumpers to earlier and having someone press the horn. With the button not pressed, there should be no voltage and a high resistance to ground, with the button pressed there should be voltage present and no resistance to ground (NEVER take a resistance reading on an energized circuit! This can destroy your multimeter and hurt you). As for the lighter, my experience has shown that it is a direct wiring job with the only protection being a fuse. That means either you have a ground, short, or open in your lighter or its circuit. Check the fuse, then check resistance to ground with your battery disconnected. It should be a relatively high value. Hope that helps!