Defogger Grid Lines Diagnosis: Notes

Opens in the grid lines of the rear window defogger can cause symptoms such as poor clearing of the rear window or crackling noise on the AM radio stations when the rear window defogger is on. If a grid line is open, that grid line will not heat which means the glass area around that grid line will not clear. Some of these opens are very small and are consider microcracks. Microcracks cause noise in the radio stations by the voltage arching across the gap of the microcrack. This arching is picked up by the radio antenna made on the rear glass or by a system where the rear window defogger is used as a radio antenna. Refer to one of the procedures below that properly addresses the concern.