Rear Window Defogger Filament Check

Filament Check
1. Attach probe circuit tester (in volt range) to middle portion of each filament.




2. It a filament is burned out, circuit tester registers 0 or 12 volts.
3. To locate burned out point, move probe to left and right along filament. Test needle will swing abruptly when probe passes the point.




- When measuring voltage, wrap tin foil around the top of the negative probe. Then press the foil against the wire with your finger.