Same thing was happening to my tuner. The connector was loose.

AH! Encouraging news! Wouldn't surprise me, it is a 4x4 and I go over lots of bumps and the likes. I'll report back my findings when I get a chance to dig into the dash. Thanks all!
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Dave Clark Georgetown, Texas MK2A 42Gb - AnoFace - Smoke Lens - Dead Tuner - Sirius Radio on AUX