Quick answer
Most often your factory amp isn't getting a remote turn-on or a data wake, or it's fed line level when it expects high level, or the reverse. Match the turn-on and the signal type to your integration sheet before you blame the speakers.
Problem
- On some vehicles your factory amplifier has to stay in the chain.
Symptoms
- You get no audio after the headunit swap.
- Your amp never wakes, just faint hiss.
Cause
- Your factory amplifier turn-on, the integration or the high-level and low-level feeds don't match the new headunit outputs.
Fix Step-by-step
- Confirm the remote turn-on or data wake against your integration sheet.
- Match the high-level or line inputs to what your factory amp expects.
- Keep the steering mute leads if your vehicle uses them.
- Check the fuses on the factory amp feeds.