Quick answer
Channels that cut out when you open a door or hit washboard usually mean the boot is chafing or a screw nicked the pair. Add grommets and service loops at hinges, route clear of pinch points, then continuity-test before clipping panels.
Problem
- You are routing speaker wire through doors or long paths in a 4WD.
Symptoms
- Rub-through in door boots.
- Noise when doors open.
Cause
- Insulation wear at door boots and hinges from flex or pinch screws.
- Corrosion or intermittent continuity through sills and tailgates on harsh 4WD builds.
Fix Step-by-step
- Plan length on the floor - Add 30–40 cm service loop per door before cutting; label both ends FL+, FL−, etc., while you can still read them.
- Door boot method - Fish from cabin; seat a grommet in the sheet metal; no bare wire over sharp lips. Common mistake: tight runs that pull through the boot when the door opens fully.
- Dual-cab / wagon sills - Run loom high along sills or under seats with flex conduit; keep away from seat-slide tracks and floor drains.
- Amp in tray or canopy - Bulkhead penetration gets a rubber grommet; no unsupported span to a lid that rattles - zip with slack for vibration.
- Continuity before clip-in - Ohm each pair from amp end with far ends twisted together; then open/close doors while wiggling boots - intermittents show up here.
- Final dress - Zip ties snug, not crushing; re-check after a gravel shakedown.
Typical failures
- Panel screw through a door card pinching a new pair - shows up weeks later.
- Water wicking into copper under heat-shrink in wet sills.