Poor Radio Reception On FM When Heated Rear Window Switched On

Poor Radio Reception On FM When The Electrically Heated Rear Window Is Switched On (Uniform Noise Level)

Fault symptoms
Poor radio reception on FM when the electrically heated rear window is switched on.
Uniform noise level.

Probable cause of fault
Break in one of the wires in the demister matrix/aerials.

Fault diagnosis hints
Check the electrically heated rear window visually as follows:
Darken the rear window by covering it with a blanket, for example. Switch on the electrically heated rear window and look for sparks on it.

Diagnostic procedure
Repair the rear window with contact paint if a fault is found.
Replace the rear window if necessary.