Problem
- Buzz or whine that follows engine RPM through your audio system.
Symptoms
- The pitch rises and falls with RPM.
- It often changes when your headlights or fans load the charging system.
- It can get worse when your phone charges from the same headunit USB.
Cause
- Different ground potentials between your headunit, amp and chassis.
- RCA running parallel to the alternator charge cable where you've run it.
- Poor alternator health, or your engine's missing its ground strap.
Fix Step-by-step
- Reroute your RCAs away from the power bundles temporarily, then retest before you dress them permanently.
- Confirm the amp ground is short and goes to clean metal.
- On heavy 4WD builds, review your charging system health. Noise can be a symptom of it as well as a sound problem.
Notes
Chasing camera interference too? You'll use the same grounding discipline in the camera flicker guide.
