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CAR HELP SITES                   TEST LIGHT 101          On this page I will explain some easy electrical diagnose any handy person can perform by themselves with only the basic test equipment.  The first thing you will need is a 12 volt test light as pictured on the left. The cost for this tester is approximately 5 to 10 dollars.  Another handy tester would be a digital voltmeter as pictured above left. This can be purchased for around $25 depending on how manyfunctions it has.  A basic meter should be all that is necessary for what I                                            will show on this page.  When an electrical  component fails to function the        first place would be to check all the fuses. On most carlines there are two  places that house fuses. One fuse box can usually be found under the left side  of the dashboard.  Some cars have the box under the right side or in the glove  box or at the extreme corners of the dashboard when opening either the right  or left front doors.  The second fuse location is under the hood in what is  known as the relay box.      Many electrical components share different circuits so when checking fuses  it is best to check all of them.  To do this turn the ignition switch to the on (or run) position and the engine off.  The top of the fuses have bare spots and this where the test light is touched to.  Put the clip of the test light to a  good ground such as the negative battery terminal or a clean metal spot on the engine.  Touch both sides of the fuse with the tester.  Both sides should light the tester bulb.  If the tester does not light check that it is grounded properly.  All active fuses will light on both sides. Some fuses such as exterior lights are inactive until the lights are turned on so if you are having a light problem turn the headlight switch on.  If there is a fuse which only lights on one side it is "blown" and needs to be replaced.  Replace the fuse with one of the same amperage such as 10, 15, 20, 25 amps etc. NEVER USE A HIGHER AMP RATED FUSE as this can burn the wires in that circuit.  If the new fuse "bows" after replacing it there is a dead short in that system and should be further diagnosed by a trained technician.                           Using a test light on light bulb sockets is basically the same.  Have the lights   on, find a good ground to attach the tester to (preferably the light socket  ground wire) and then probe the connector terminals inside the socket.   Always replace a bulb with the same number as the old one.  If the bulb has  two filaments make sure it is correctly installed.  There are two tabs on the  outside of the bulb base one being higher than the other.  Check the socket  and match up the tabs for correct  installation. All of the above tests can also be done with a digital voltmeter.  Set the meter to 20 volts and all good readings will register at 12 volts or a little above.