Expert: Peter G. Lee - 10/7/2006

Question
I have a JVC CD player installed in my 93 Jeep Grand Cherokee.  It worked fine then one day I started the vehicle and the only sound I got was some random static and pops that sounded like maybe a speaker wire was loose.  We took the unit out and reconnected ALL the wires, checked connections, etc.  The unit will emit some sound, through one rear speaker if playing a CD, however once you plug the antenna into the back of the unit the sound completely disappears.  There is no problem with power to the unit and visually it is working correctly.  How do I troubleshoot this?

Answer
Hi Kimberly,
The only way to test is on the bench, thereby eliminating the car from the equation which you say you have checked anyway????

You’ll need a 12v power supply, battery or that old CB radio PSU gathering dust.
A speaker and leads, connectors for rear of radio.

Hook up radio with +12v live and 12v ignition joined together for the time being to the 12v + side of the power source.
Negative to, you got it, negative side of power source. The radio should now operate OK, well, light up anyway and the display work. Ignor the other wires for amp, lights, phone etc.

Connect a ‘make do antenna’, doesn't need to be fancy, just a yard of flex into the centre connection will do to pick up "something". (chrck with a CD only after you have established basic functions are working, ie radio).

You should now connect the speaker to any pair of speaker wires and see if you have any sound, check the other 3.

If it still results in the fault as described then it is the radio and not the car and obviously if it works OK then you need to triple check the car again.

If it's over three years old, bin it and replace it or you will end up going around in circles with one fault after another.

Less than three years old? Repair shop, as it is probably n internal on-board fault, although why plugging in the antenna should make any difference as the only relevant connection would be EARTH via the outer coax to the body of the car.

Hope this helps but it is a difficult one without having hands on.
Peter