Quick answer
If you lose a channel when you open a door or hit washboard, the boot's usually chafing the pair or a screw has nicked it. Add grommets and service loops at the hinges, then route clear of pinch points. Continuity-test before you clip the panels back on.
Problem
- You're routing speaker wire through doors or long paths in a 4WD.
Symptoms
- You find rub-through in the door boots.
- Noise when you open a door.
Cause
- If your run flexes at the door boots and hinges, or a screw pinches it, the insulation wears through.
- On a harsh 4WD build, you get corrosion or intermittent continuity through the sills and tailgate.
Fix Step-by-step
- Plan the length on the floor: add a 30 to 40 cm service loop per door before you cut, then label both ends FL+, FL−, and so on while you can still read them.
- Door boot method: fish from the cabin, then seat a grommet in the sheet metal. No bare wire over a sharp lip. Common mistake: a tight run that pulls through the boot when you open the door fully.
- Dual-cab and wagon sills: run the loom high along the sills or under the seats in flex conduit, then keep it clear of the seat-slide tracks and floor drains.
- Amp in the tray or canopy: fit a rubber grommet in the bulkhead penetration. Don't leave an unsupported span to a lid that rattles, zip it with slack for vibration.
- Continuity before clip-in: twist the far ends together, then ohm each pair from the amp end. Open and close the doors while you wiggle the boots. You'll catch intermittents here.
- Final dress: zip ties snug, not crushing. Re-check after a gravel shakedown.
Typical failures
- A panel screw through a door card pinching a new pair, which you don't notice for weeks.
- Water wicking into the copper under heat-shrink in wet sills.