High-pitched whine
Our local dealer recently repaired the GPS on our Magnadyne M4-LCD by replacing the SD card. Since the repair, we have a high-pitched whine coming from (or at least caused by) the Magnadyne unit: when the unit is on, the whine is present; when the unit is off, there is no whine. The whine differs in pitch depending upon the engine’s RPMs.
Because the whine differs in pitch depending upon the engine’s RPMs, it sounds to me like the electronics in the Magnadyne unit are somehow interfering with or picking up interference from the engine’s electronics. That’s just a wild guess though.
I’m wondering if the dealer had to unwire/remove the unit to make the repairs, and if so, is it possible that a ground wire didn’t get put back properly? (I have asked the dealer this question, but they never admit to any problems with their work.)
Or is there another possible cause?