Heated rear window (Audi A4 B5)

Exposed right roof pillar

1 - antenna connection;
2 - connection of rear heated glass;
3 - antenna wire to the radio receiver;
4 - control line from the radio receiver;
5 - antenna amplifier;
6 - wire from the heated glass switch.

The ground point (arrow) for the heated rear window and the rear window antenna is located on the right rear roof pillar. It is accessible after removing the roof pillar trim.

The heated rear window is switched on and off directly via a switch on the instrument panel. When the ignition is on, current flows to the switch from the X-contact discharge relay via the fuse in the white/yellow wire. An electronic switching circuit with a timer, which is integrated into the heated rear window switch, cuts off the current supply to the glass after approximately 10 minutes.

Troubleshooting

If the heated rear window remains cold, consider the following options:

1. Defective fuse.

2. Defective switch. Dismantle (as described in this chapter) and check with an electric test lamp whether there is voltage in the white wire with the ignition on and the switch pressed.

3. Remove both roof pillar covers near the rear window. This is easier to do after removing the rear cargo pocket and the side seat trim.

4. Check the supply wire to the rear window: Using a test lamp, determine if there is voltage at the back in the white supply wire on the left side of the window. (This also applies to vehicles with an antenna in the rear window.)

5. On the right roof pillar, check whether the glass has good contact with the ground.

6. Damaged heating wires can be repaired with conductive silver varnish, which is sold in related stores.