Car Stereos: loss of right side audio on 2005 dodge ram radio, using a digital multimeter, infinity systems

Question
I suddenly lost all sound from the right front AND rear speakers in my trucks stock stereo. Fade and balance controls work fine for the left, but nothing comes from the right anymore.  Is the system shot?

Answer
Hi Vin,

Sorry about the very long delay in answering your question.

It's really hard to say where the problem is in your truck's audio system.  Earlier versions of the Ram, when equipped with Infinity audio systems, used separate amplifiers mounted on the front door speakers; each amplifier would run the door speaker, rear speaker and front tweeter on that side of the truck.  However, the 2005 Ram is different.  If your truck has an Infinity audio system, there's just one amplifier, located behind the glove box.  However, some Infinity systems use a 2-channel output from the head unit to the amp; instead of separate front and rear, left and right channels between the head unit and amp, there's only a pair of left and right channels.  Fader and volume functions are handled by the amplifier, using digital control signals generated by the head unit.  That means a problem with the head unit's output could easily affect the front and rear speakers on one side.

If I were troubleshooting this problem, I'd probably start by using a digital multimeter to test for an audio signal at each speaker.  This can be done using a meter's AC voltage function, probing the speaker wire at the speaker for voltage that increases as the volume goes up.  If you find an audio signal on the wire at the speaker, but don't have any sound, then the speaker is bad.  If you're not getting audio signals, then you'll know that the problem is in the amplifier or head unit.  The next thing I'd probably try is reversing the left and right wire connections at the back of the head unit.  This would require cutting the wires and temporarily splicing them to the opposite outputs.  If switching the connections causes the right speakers to start playing, and the left to shut off, then it indicates a problem with the head unit.  However, if the same speakers are still playing after the signal wires are switched, then the amplifier is the likely trouble spot.

Of course, if you have a base audio system without a factory amp, then a lack of audio signal at the speaker location would probably indicate a bad head unit.

Hope this helps!

Brian