Diagnosing amplifier protection mode faultsEver had an amp stop working and turn its "Protect" light for no aparant reason ? Me too ! This great article outlines the steps you can take at home to diagnose why your car stereo amplifier is going into protection mode.
1. Check amp power cables, all terminals & fuses for secure mounting and clean connections. Check ground cables securely attached to car chassis.
2. Check amp power cables for voltage using a multimeter. Connect to the + & - and confirm 12V or more. Verify 11V or more with the engine off, 12v or more with it on.
3. Check amp start wire from head-unit for voltage using a multimeter. Connect to the remote wire & -, verify 11V or more with the engine off, 12v or more with it on.
4. Check if the amp is hot. If it feels very hot (burningly hot) and goes into protection mode, verify your speakers impedence is within the amplifiers load specification. If they are, then give your amp more ventilation.
5. Remove speaker wires from amp and start up your system. If the amp does not go into protection check the speaker cables for short circuits, cuts, breaks. If the cables are OK, check your speakers impedence with a multimeter as the speaker itself might have a short or damaged coil.
If the amp continues to go into protection mode, leave the speakers disconnected and go to step 6.
6. Remove the RCA cables from amp and start up your system. Remember to tape over the exposed RCA leads so u don't short by accident.
If the amp does not go into protection mode when u start it up you have a problem with the RCA cables or the headunit.
Check the RCA leads for correct installation at the head unit and amp, check for cable damage or shorts. Consult your headunit manual for troubleshooting if the RCA's are OK.
7. If your amp still goes to protections then your amp needs to be serviced by a professional.