How to Test a Car Amplifier

Hook up the power (red) and ground (black) wires. In order for an amplifier to work, it must have 12 volt power coming in, and a good ground. If the goal is to test it to see if it works, then there is no need to mount it in most cases. Some amps require the chassis to be grounded, but the large majority do not. One of the quickest ways is to simply touch the power wire from the amp to the positive post of the battery and the ground wire to the negative battery post. If the power light comes on, it can be ascertained that the amplifier has a good circuit board.

Connect a speaker to the amplifier. To determine if the amplifier actually puts out sound, hook the speaker wires or RCA cables coming out of the head unit to the speaker in jacks, and then connect a speaker to the output side of the amp. If the power to the amp comes on but there is no sound, there is a good chance that the amplifier has been overloaded in the past and will not work. If sound does come out of the speaker, and it does not sound distorted or fuzzy, the amplifier is good.

Check all available fuses to ensure continuity. Every amplifier will contain at least one fuse, usually located in the amp chassis itself. Normally, they are the two-pronged type with a color coded, plastic body. If the amp does not turn on when power and ground are correctly connected, check the fuse first before assuming the circuitry is bad inside. If the fuse on the amp body is fine, check to see if there is an inline fuse on the power wire. Many times it is in a black or clear plastic casing that splits down the middle or twists apart. The fuse found in this casing will be a round glass fuse with metal on both ends and a small wire going through the middle of it. If the fuse is cracked or corroded, or the wire inside it is in two pieces, the fuse is bad and must be replaced in order for the amp to turn on.