Amplifier in Protection Mode

Protection LED illuminated, no output or intermittent output.

Illustration in preparation Description: Decision tree: protection light on → check impedance (too low?) → check temperature (too hot?) → check for speaker short → check voltage → internal fault

Causes and checks:

Thermal protection (most common): - Touch heatsink — too hot to hold (>60°C) = thermal - Fix: Better airflow, reduce power, move amplifier, add fan

Low impedance: - Check speaker wiring configuration - Measure DC resistance of speaker load with DMM (should match rated impedance ± 20%) - 1Ω load on an amp not rated for 1Ω = protection

Speaker short circuit: - Disconnect speakers. If protection clears: short in speaker wire or driver - Check for wire pinched under seat, in door (common failure point) - Test speaker resistance individually

Voltage too low: - Measure supply voltage during operation - Below 10.5–11V: protection engages on most amps - Charge battery, check alternator, reduce power draw

Internal fault: - If all external checks pass and protection persists - Return for warranty repair or professional bench test