An email came in through the customer support address asking for some help with a door speaker that wasn't working. The assumption was that it was a bad speaker and he wanted to know how to test it. Rather than explain how to test a speaker I wanted to verify that it was in fact a speaker problem. There are many components before the speaker and any one of them could be the problem. Here's the procedure for testing to see where a problem lies.
Let's assume our system has a head unit, a crossover, a two channel amplifier and two door speakers with only the right speaker working (the left speaker is not working). If the door speakers are behind the door panels then we want to make sure the speaker is the problem before removing the panel. We'll work backwards starting with the amplifier and ending at the head unit.
With the vehicle and the stereo turned off disconnect the speaker wires for both the left and right speakers at the amplifier. Now connect the left speaker to the right amplifier output (which we know works). Turn on the stereo system and make sure the balance is set to the middle position.
If the speaker still doesn't work then the problem is somewhere between the amplifier and the speaker itself. It could be the speaker wire, any of the wiring connections or a bad speaker. If the speaker has a passive crossover between the amplifier and the speaker this could also be the problem. At this point we'll need to remove the speaker from the door and test it on the amplifier using short lengths of speaker wire. If the speaker works then the wiring is the problem. If it doesn't work then it is indeed a bad speaker.
If the speaker did work when we put it on the other amplifier channel then we know the problem is not in the speaker and we'll test the next component. Turn off the stereo system.
Now we'll need to see if the amplifier channel is bad. Put the left speaker back on the left amplifier channel and the right speaker on the right amplifier channel. This returns the speaker wiring to its original configuration. Again, with the vehicle and stereo off unplug the RCA cables from the amplifier's input and switch them so the left cable is in the right input and vice versa. Turn on the stereo system.
If the left channel still does not work and the right channel does then you can suspect the amplifier is the problem. This is because you've eliminated the components after the amplifier as well as the components before it. If the problem was traveling through the left side of the stereo system then it would have shown up in the right amplifier channel when the cables were switched. Have the amplifier checked out by a professional repair tech.
If the left channel now works and the right channel does not you know the problem lies before the amplifier. You also know it is a problem along the left side of the system since the problem followed the cable switch. It could be in the cables or some other component's left channel. Turn the stereo off and put the RCA cables back to their original configuration (left cable to left amplifier input and vice versa).
For any intermediate components between the amplifier and the head unit follow these steps for each one. We only have a crossover so we'll just do this once. Begin by testing the RCA cables between the intermediate component and the amplifier. Unplug both RCA cables from the intermediate component's output. Now plug the working channel's RCA cable into the non-working side of the crossover. In our case the working channel is the right so plug the right RCA cable from the amplifier into the left side of the crossover. Turn on the stereo system.
If the right channel continues to work then you know the problem is in the RCA cables between the amp and the crossover.
If the right channel no longer works then you know the problem is not the RCA cables. Verify this by turning off the stereo system, plugging the left RCA cable from the amplifier into the right RCA output of the crossover. Turn the stereo system back on. If the cables are good then you should have output from the left speaker. You should not skip this verification step because it is possible for a problem to exist in both the cable and in another component.
Turn off the stereo system and return the RCA cables to their normal position.
At the input of the intermediate component (in our case the crossover) flip the RCA cables around (left to right input and vice versa). Turn on the stereo system.
If the right channel continues to work and the left channel continues to not work then you know the problem is in the intermediate component. Replace or repair this component.
If the problem is now in the right speaker and the left speaker works then the problem lies before the crossover. Turn off the stereo system and return the RCA cables to their normal places.
Pull out the head unit from the dash so you can access the RCA cables. Unplug both RCA cables from the head unit. Do not disconnect any other wiring. Plug the right RCA cable into the left channel of the head unit. Turn on the stereo system.
If the right speaker works then you know the problem is not the head unit. The problem lies in the RCA cables that run between the head unit and the intermediate component (if you have one, the amplifier if you don't). Confirm this by shutting down the stereo system, unplugging the right RCA cable and plugging the left RCA cable into the right output of the stereo system. Turn on the stereo system. There should be no output because the left RCA cable between the head unit and the next component is faulty.
If the right channel no longer works then you know the problem is in the head unit. Confirm this by shutting down the stereo system, unplugging the right RCA and plugging the left RCA into the right output of the stereo system. Turn on the stereo system. There should be output from the left speaker. If there is no output in this configuration then you have both a bad head unit and a bad RCA cable between the head unit and intermediate component. This is rare but possible.
That's the testing and troubleshooting procedure I use. If anything is unclear or if you think there is an error please let me know. Use the Contact link in the bottom right column of this page.
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