Checking the rear window defroster (VW Passat B5)

Using a voltmeter probe to detect a break in the rear window defroster wire

Using a Voltmeter to Find a Broken Rear Window Defogger Wire

Using a voltmeter to locate a broken rear window defroster wire

The rear window defroster is a plurality of horizontal conductors sprayed onto the inner surface of the rear window.



To detect a break in the rear window defroster wire, turn on the ignition and the rear window defroster switch.

Connect one voltmeter probe to the vehicle ground and wrap the other probe with foil and move the foil along the heater wire, see Fig. Using the voltmeter probe to detect a break in the rear window heater wire.

Connect the voltmeter probe to the center of each rear window defroster wire. If the voltmeter shows about 5 volts, the defroster wire is OK. If the voltmeter shows 0 volts or 12 volts, there is a break in the defroster wire, see Fig. Using a voltmeter to locate a broken rear window defroster wire.

To locate a break in the heater wire, connect one probe of the voltmeter to the positive terminal of the heater and move the other probe along the heater wire from the negative terminal of the heater. The point at which the voltage indicated by the voltmeter drops from a few volts to zero is the break in the heater wire, see Fig. Using a voltmeter to locate a break in the rear window defroster wire.