Car Stereos: Right Side Channel Periodically works, using a digital multimeter, factory radio

Question
Brian-
Cool name by the way...
I have just finished reading one of your responses about changing out speakers in the 2002 Liberty.  A while back the right channel quit working.  Well it works from time to time for about 3 seconds.  I went and bought some 6 1/2 rounds from Sony and pulled the panels off only to find that the wiring was VERY different.  After reading your response to Julie I found that the reason for the wiring is the amplifiers.  Would the right side channel's periodic working be attributed to the amplifier going out?  Do you have any suggestions of how to get this baby working again?

Thanks,
Brian  

Answer
Hi Brian,

I'd say if all the speakers on the right are failing at the same time, then the problem really has to be the factory amp--it's responsible for driving all three speakers on that side.  If you want to keep all the speakers working, then you'll need to have a working amplifier.  The real question is, do you have a defective amplifer, or is it just not getting power?

I'd suggest testing the power wires at the amplifier, using a digital multimeter.  The power wires are black/red (+) and black (ground).  If the factory radio is switched on, and you test the voltage between these wires, you should get 12 volts.  If the voltage is present, but you aren't getting any sound, then the amp is defective.  On the other hand, if the voltage is dropping out, then it's likely that there's a broken power or ground wire leading to the amp.  The most likely place for a broken wire is inside the flexible conduit that leads from the vehicle body into the door; it's very common to have a break or a poor connection here.  (It's possible that the door to body connection runs through a Molex plug; in this case, there may be a loose Molex terminal).  

If you find a voltage problem, you can try to find the broken connection and repair it.  However, if the amplifier is defective, then your best bet is to replace it; you can order a replacement through a dealer's parts department, or try to find a used one.  

Hope this helps!

Brian