Car Stereos: Sentra 05 stock radio, rockford amp, nissan sentra

Question
Recently my stock radio system fuse blew on my 05 nissan Sentra 1.8. The rear speakers work only. Everytime I replace the fuse it automatically blows. The stereo is stock fosgate system with amp etc. Can you explain why the fuse keeps blowing. Thanks,

Answer
Hi Marcelo,

From your description, it sounds like it's the amplifier fuse that's blowing.  The Rockford amplifier runs the front component speakers and subwoofer, while the rear speakers are driven directly from the head unit.  That's why the rear speakers continue to work in your system.

Generally, if a fuse is blowing, it's due to a short circuit.  The question is whether the short is an internal problem in the amplifier, or somewhere in the power wiring between the fuse and the amplifier.  

If the fuse doesn't blow until you turn the radio on, then it's most likely that the problem is inside the Rockford amp.  However, there is a chance that a problem with a speaker, or with the subwoofer, is causing the amplifier's fuse to blow.  

On the other hand, if the fuse blows instantly as soon as you place it in the slot, then there may be a short somewhere on the power wiring leading to the amplifier; although it's still possible that there's an internal short in the amplifier's power supply section.

You can look for shorted speaker or power wiring by unplugging the amplifier, and probing the wires in the plug with a multimeter.  The amplifier should be located under the rear deck in the trunk.  The best way to test for a short is to set the multimeter for the "continuity" functions, and attach the black probe to chassis metal (or to the black ground wire in the amplifier plug).  Then, probe each speaker output wire and each power wire terminal in the plug.  The amplifier plug should have two power wires, each white with a red stripe.  The speaker output wires should be red/black, yellow/green, gray/blue, white/orange, brown, brown/white, violet, and green/yellow.  If any of these wires shows continuity with chassis ground, then it's the likely cause of the fuse blowing.  On the other hand, if none of the wires is grounded, then the problem is likely internal in the factory amplifier.

Hope this helps!

Brian