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No-Bass Troubleshooting Checklist
Work through it in order with the car off and the volume down. Most problems are a setting, a fuse or a loose wire.
1. Power
- Fuse near the battery is good
- Fuses on the amp are good
- About 12–14.4 V between amp power and ground terminals (car on)
- About 12 V on the remote terminal when the stereo is on
- Ground is short, tight and bolted to bare metal
2. Protect mode
- No protect light on the amp
- With speaker wires disconnected, does protect go away? (If yes, the problem is in the sub wiring or the sub)
- Final impedance is not lower than the amp is stable at
- Amp is not overheating (needs airflow)
3. Head unit
- Subwoofer output turned ON in the stereo settings
- Sub level turned up
- Fader not cutting the outputs your RCAs use
- Low-pass set around 80 Hz on the head unit
4. Signal and amp settings
- RCAs firmly plugged in at both ends, in the right outputs
- Tried a known-good RCA cable
- Amp filter set to LPF, not HPF
- Gain is not all the way down
- Bass remote plugged in and turned up
5. The sub
- Speaker wire not pinched, loose or touching metal
- Coil reads close to its rating on a multimeter (4 Ω coil ≈ 3–4 Ω; “OL” = open coil)
- Cone moves smoothly when pressed gently, no scraping
My readings
| Test | Reading | OK? |
|---|---|---|
| Battery voltage | ||
| Amp power to ground | ||
| Remote terminal | ||
| Sub coil 1 (Ω) | ||
| Sub coil 2 (Ω) |
Disconnect the battery before working on power wiring. If you are not sure, use a professional installer.
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