JBL GT5-A402, Service Manual, Page: 6 / 15

Amplifier Troubleshooting Guide
1. Status LED on Amplifier not Lit - Head Unit (Source) Turned ON
Verify:
A. Remote turn-on wire from source to amplifier has proper voltage
B. Power (B+) connections at amplifier, terminal blocks, and battery are secure
C. Ground (GND) connections at amplifier and vehicle chassis are secure
D. Battery B+ fuse (if used) is OK
E. Amplifier fuse is OK
F. B+ at battery and B+ at amplifier has proper voltage
2. Status LED’s Lit, No Output from Speakers in Normal Operating Condition
Verify:
A. RCA cables from amplifier to source are securely connected
B. Volume adjustment on amplifier is correctly adjusted
C. Source is ON and playing
3. Engine Noise From Speaker(s)
Turn source OFF, Disconnect RCA cables at amplifier. If noise stops, check equipment & cables leading
to amplifier.
Verify:
A. RCA cables are of good quality with no breakage to internal shields
B. RCA cables from source to amplifier are not run alongside any power cables
4. Amplifier Output Distorted Music
Verify:
A. Source output music to amplifier is not distorted
B. Source output sensitivity is correctly adjusted
5. Amplifier Shuts Down, Green LED’s are Lit - Amplifier is in Thermal Protection Mode
Verify:
A. Amplifier is mounted with adequate air circulation around heatsinks or vents
B. Amplifier is not mounted under carpet or sealed enclosure
C. Speakers meet correct impedance for application (mono or stereo hookup)
6. Amplifier Does Not Turn ON, and Red LED is Lit Amplifier (and not Connected to a Shorted Speaker)
Verify:
A. Speaker crossover (if used) is not defective
GT5-A402, GT5-S422
5